importance of vegetarian diet essay

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Vegetarianism Essay

This is a model  vegetarianism essay .

As I always stress, you should  read the question very carefully  before you answer it to make sure you are writing about the right thing.

Take a look at the question:

Every one of us should become a vegetarian because eating meat can cause serious health problems.

To what extent do you agree or disagree?

Staying on topic

If you rush to start writing and don't analyse the question and brainstorm some ideas you may include the wrong information.

There are religious or moral arguments for not eating meat, but if you discuss those you will be going off topic .

This question is specifically about the health problems connected to eating meat.

So you must discuss in your answer what some of these problems are and if you think there are real health risks or not.

Knowing about the topic

And don't get worried that you do not know much about diet and health.

As part of your IELTS study it will help if you know the basics of most topics such as some health vocabulary in this case, but you are not expected to be an expert on nutrition.

Remember, you are being judged on your English ability and your ability to construct an argument in a coherent way, not to be an expert in the subject matter. So relax and work with

Organisation

In this vegetarianism essay, the candidate disagrees with the statement, and is thus arguing that everyone does not need to be a vegetarian.

The essay has been organised in the following way:

Body 1: Health issues connected with eating meat (i.e. arguments in support of being a vegetarian Body 2: Advantages of eating meat

Now take a look at the model answer.

Model Essay

You should spend about 40 minutes on this task.

Write about the following topic:

Give reasons for your answer and include any relevant examples from your own experience or knowledge.

Write at least 250 words.

IELTS Vegetarianism Essay - Sample Answer

Vegetarianism is becoming more and more popular for many people, particularly because of the harm that some people believe meat can cause to the body. However, I strongly believe that it is not necessary for everybody to be a vegetarian.

Vegetarians believe that meat is unhealthy because of the diseases it has been connected with. There has been much research to suggest that red meat is particularly bad, for example, and that consumption should be limited to eating it just a few times a week to avoid such things as cancer. Meats can also be high in saturated fats so they have been linked to health problems such as cardiovascular disease and diabetes.

However, there are strong arguments for eating meat. The first reason is that as humans we are designed to eat meat, which suggests it is not unhealthy, and we have been eating meat for thousands of years. For example, cavemen made hunting implements so that they could kill animals and eat their meat. Secondly, meat is a rich source of protein which helps to build muscles and bones. Vegetarians often have to take supplements to get all the essential vitamins and minerals. Finally, it may be the case that too much meat is harmful, but we can easily limit the amount we have without having to cut it out of our diet completely.

To sum up, I do not agree that everyone should turn to a vegetarian diet. Although the overconsumption of meat could possibly be unhealthy, a balanced diet of meat and vegetables should result in a healthy body.

(264 words)

You should begin by intoducing the topi c. The introduction in this vegetarianism essay begins by mentioning vegetarians and the possible harm of eating meat .

It then goes on to the thesis statement , which makes it clear what the candidate's opinion is.

The first body paragraph has a topic sentence which makes it clear that the paragraph is going to address the possible health issues of eating meat.

Some reasons and examples are then given to support this.

The second body paragraph then has a topic sentence which makes it clear that the main idea is now about the arguments for eating meat .

The conclusion in this vegetarianism essay then repeats the opinion and gives the candidates final thoughts.

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What to know about the vegetarian diet

People following a vegetarian diet do not eat meat or fish but may continue to eat eggs and dairy products.

A person does not have to eat meat to get all the nutrients they need for good health. A meat-free diet can lead to better health for several reasons.

One reason is that many people who follow a vegetarian diet tend to consume a high proportion of fresh, healthful, plant-based foods, which provide antioxidants and fiber. When a person decides to follow a meat-free diet, they often become more active in making overall healthy choices.

Many studies agree that a vegetarian diet can offer a range of health benefits.

Studies show that a vegan or vegetarian diet may reduce the risk of cardiovascular disease and various types of cancer .

A non-meat diet may also reduce the risk of metabolic syndrome, which includes obesity and type 2 diabetes .

According to a 2019 Gallup poll , 5% of people in the United States describe themselves as vegetarian, including 2% of people aged 55 and over, 8% of those aged 18–34 years, and 7% of people aged 35–54.

This article will focus on the lacto-ovo-vegetarian diet, which includes dairy products and eggs.

Click here to learn about some other popular diets.

What foods do vegetarians eat?

A vegetarian diet can provide a wide variety of healthful, nutritious foods, but what the person eats will depend on the type of diet they are following and their personal food choices.

There is a variety of diets that come under the umbrella term vegetarian:

• Lacto-ovo-vegetarians avoid both meat and fish but consume dairy and eggs.
• Lacto-vegetarians consume dairy products but no eggs.
• Ovo-vegetarians consume eggs but no dairy.

Some people who do not eat meat will eat fish. This is a pescatarian diet, rather than a vegetarian diet.

A vegan diet excludes all animal-based foods.

People following a vegetarian diet must make careful choices about what they eat to ensure that they meet their nutritional requirements. Some people may need supplements.

Nutrition resources

For more science-backed resources on nutrition, visit our dedicated hub .

A growing number of younger people are adopting a vegetarian diet, as the Gallup poll shows.

They may do this because:

• it brings health benefits
• it is a more ecologically sustainable option
• they have concerns about the treatment of animals
• it is part of a broader lifestyle choice

Some people also avoid meat and animal products for religious reasons.

Here are some ways in which avoiding meat products can enhance a person’s health.

Weight : Switching to a vegetarian diet may help a person lose weight, at least in the short-term, according to a 2016 meta-analysis . Scientists need to carry out longer term controlled studies to understand how a vegetarian diet might affect weight.

Cholesterol : A systematic review published in 2015 concluded that people who follow a vegetarian diet are likely to have lower overall cholesterol levels.

Cancer : A study of data for nearly 70,000 people found evidence that the incidence of cancer overall was lower among vegetarians than non-vegetarians. The authors suggested that a non-meat diet may offer some protection from cancer.

Heart health : Authors of a 2014 study found a lower risk of cardiovascular disease in people who followed a vegetarian diet in India. Studies in western countries had already produced similar results.

Diabetes : People who follow a vegetarian diet may be less likely to have type 2 diabetes. One reason for this may be a higher intake of whole grains, fruits, vegetables, legumes, and nuts, and a lower intake of unhealthful fats.

These benefits will not automatically happen when a person stops eating meat. Alongside a vegetarian diet, people need to make sure they:

• get the right number of calories
• focus on a variety of fruits, vegetables, and whole grains
• limit their intake of processed foods and alcohol
• avoid unhealthful fats and added sugar and salt
• engage in an overall healthful lifestyle, with plenty of exercise
• avoid smoking

What are the health benefits of a vegan diet?

Sustainability

In addition to the health benefits, experts say a plant-based diet is more sustainable, as it causes less harm to the environment than a meat-based diet.

What else makes a diet sustainable? Find out here.

Tips for getting started

Here are some tips for switching to a vegetarian diet:

• Start learning about the nutrients required and how to obtain them.
• Get some tips and recipes from vegetarian websites, a local health food shop, or a nutritionist.
• Make a weekly shopping and meal plan.
• Focus on a variety of meat-free dishes that provide a complete protein, so that you do not end up eating as before but just leaving out the meat.
• Consider making the change gradually, for example, over a month.
• Start with familiar meat-free foods, such as mac and cheese and salad, and add to your repertoire over time.

A gradual change may work better for two reasons:

It is more likely to become a lifestyle and a long-term move.

Sudden dietary changes, such as an increase in the consumption of beans or vegetables, might lead to temporary digestive problems, such as bloating.

The Academy of Nutrition and Dietetics have a range of tips for people who want to stop eating meat:

Choose whole grain products , such as whole wheat bread, wild or brown rice, and whole grain cereals, as these can provide B vitamins .

Vary the diet , with whole grains, fruits, vegetables, legumes, nuts, and so on.

Use eggs and dairy products in moderation , or try adding soy milk.

Ask a healthcare professional about supplements , especially vitamin B-12.

Ensure a sufficient intake of vitamin D , especially if exposure to sunlight is low.

Check the labels of “healthful” vegetarian snacks to ensure they do not contain a lot of sugar, salt, or other additives.

Remember that junk food and fast food can be unhealthful and high in calories, whether they are vegetarian or not.

They also suggest reducing the intake of high sugar and high fat foods.

Learn more here about how to get started on a plant-based diet.

The nutrients you need

Some scientists say that a vegetarian diet is beneficial to people of all ages, but they note the need to plan appropriately to obtain the whole range of essential nutrients.

The chart below lists some of nutrients that a person following a vegetarian diet may lack , how much of them an adult requires, and some examples of foods that contain them. Some people may also need supplements to boost their levels of these nutrients. Needs may increase during pregnancy and breastfeeding.

A vegetarian diet will not guarantee good health, but it can contribute to overall healthful dietary choices. A person still needs to make healthful choices, such as avoiding added sugar and high fat processed foods.

Parents and caregivers of children who follow a vegetarian diet should ensure the child is obtaining the nutrients they need for their age and stage of growth. This may include making sure the child is not just eating the family meal minus the meat.

What are the key nutrients a person needs? Find out here .

The 2015–2020 Dietary Guidelines for Americans provide an eating pattern to help people eat healthfully on a vegetarian diet. It advises on suitable quantities of:

• dark green vegetables
• red and orange vegetables
• starchy and other vegetables
• whole and refined grains
• dairy products
• proteins foods, such as eggs, legumes, soy products, nuts, and seeds

People who follow a vegan diet may need supplements. Click here to find out which ones beneficial.

Recipes and ideas

Many premade products are available for those who are busy or do not feel confident in their cooking skills. They include:

• premade meals (always read labels to choose the most healthful options)
• burgers and sausages made from meat substitutes (these may be high in sodium and fat)

Most restaurants now offer vegetarian and vegan options.

However, cooking at home is often more economical, and a person can ensure they use fresh, healthful ingredients.

Here are some ideas for meals and snacks without meat, as suggested by dietitians:

Cauliflower no-crust quiche recipe

Spaghetti squash orecchietti mushroom soup

According to the Academy of Nutrition and Dietetics , a well-planned vegetarian or vegan diet can be healthful for people at all stages of life.

Plant-based diets may help reduce the risk of heart disease , cancer, type 2 diabetes, obesity, and other conditions. Plant-based foods also tend to be more environmentally sustainable than animal-based foods.

It is worth remembering, however, that going veggie will not make a person healthy overnight. To see improvements in health, it is essential to plan well, include a variety of ingredients, and make the diet part of an overall healthful lifestyle.

For people who wish to reduce their meat intake but feel this is too difficult, a gradual or partial switch may be a suitable option.

The American Heart Association (AHA) offer tips for going meatless, especially for people who would like to lower their cholesterol levels and decrease their risk of heart disease.

My 14-year-old daughter has decided to become vegetarian, but it is difficult for me because her father loves meat. I am now cooking two separate meals every night. Do you have any tips?

Cooking two different meals after a long workday is really tough!

Perhaps you could grill, bake, or broil several different meat items on the weekend to use throughout the week? Dad can have a piece of chicken alongside the beans, rice, or veggie dish you have prepared for your daughter.

Another idea may be to prepare some mixed vegetarian dishes ahead of time that you can reheat and accompany with the same vegetables you have prepared for dad.

I have always been a fan of cooking ahead for the week and even freezing the home-cooked meals rather than buying premade options.

Contrary to popular belief, you can use fresh, frozen, or canned veggies and get similar nutritional content.

Steamable microwave veggies are a great time-saver.

Adding canned beans to any rice dish or salad is a great way to add complete protein to the meal.

Maybe dad would also agree to one meat-free night a week?

Kathy W. Warwick, R.D., CDE Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Last medically reviewed on January 20, 2020

• Heart Disease
• Nutrition / Diet
• Complementary Medicine / Alternative Medicine
• Vegan / Vegetarian

How we reviewed this article:

• Appendix 5. USDA food patterns: Healthy vegetarian eating pattern. (n.d.). Dietary Guidelines 2015–2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/
• Appendix 7. Nutritional goals for age-sex groups based on dietary reference intakes and  Dietary Guidelines  recommendations.  https://health.gov/dietaryguidelines/2015/guidelines/appendix-7/
• Building a healthy vegetarian meal: Myths and facts. (2019). https://www.eatright.org/food/nutrition/vegetarian-and-special-diets/building-a-healthy-vegetarian-meal-myths-and-facts
• Calcium: Fact sheet for health professionals. (2019). https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/
• Dining out for vegetarians. (2019). https://www.eatright.org/food/nutrition/vegetarian-and-special-diets/dining-out-for-vegetarians
• Dinu, M., et al. (2017). Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies.  https://www.tandfonline.com/doi/abs/10.1080/10408398.2016.1138447?journalCode=bfsn20
• Food sources of 5 important nutrients for vegetarians. (2018). https://www.eatright.org/food/nutrition/vegetarian-and-special-diets/food-sources-of-important-nutrients-for-vegetarians
• Hrynowski, Z. (2019). What percentage of Americans are vegetarian? https://news.gallup.com/poll/267074/percentage-americans-vegetarian.aspx
• Huang, R.–Y., et al. (2016). Vegetarian diets and weight reduction: A meta-analysis of randomized controlled trials. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699995/
• Iodine: Fact sheet for health professionals. (2019). https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
• Iron: Fact sheet for health professionals. (2019). https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
• Medawar, E., et al. (2019). The effects of plant-based diets on the body and the brain: A systematic review. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6742661/
• Olfert, M. D., & Wattick, R. A. (2018). Vegetarian diets and the risk of diabetes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6153574/
• Position of the Academy of Nutrition and Dietetics: Vegetarian diets. (2016). https://www.eatrightpro.org/-/media/eatrightpro-files/practice/position-and-practice-papers/position-papers/vegetarian-diet.pdf
• Shridar, K., et al. (2014). The association between a vegetarian diet and cardiovascular disease (CVD) risk factors in India: The Indian Migration Study.  http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0110586
• Tantamango-Bartley, Y., et al. (2014). Vegetarian diets and the incidence of cancer in a low-risk population. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3565018/
• Vegetarian diet. (2015).  http://www.nlm.nih.gov/medlineplus/vegetariandiet.html
• Vegetarian, vegan, and meals without meat. (2017).  https://healthyforgood.heart.org/eat-smart/articles/vegetarian-vegan-and-meals-without-meat#.WJ3ZYRKLRp8
• Vegging out: Tips for switching to a meatless diet. (2018). https://www.eatright.org/food/nutrition/vegetarian-and-special-diets/vegging-out-tips-on-switching-to-a-meatless-diet
• Vitamin B-12: Fact sheet for health professionals. (2019). https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
• Vitamin D: Fact sheet for health professionals. (2019). https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• Wang, F., et al. (2015). Effects of vegetarian diets on blood lipids: A systematic review and meta-analysis of randomized controlled trials. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4845138/
• Willett, W. et al (2019). Food in the Anthropocene: The EAT–Lancet Commission on healthy diets from sustainable food systems. http://academiacienciasfarmaceuticas.cl/wp-content/uploads/2019/01/The-Lancet.pdf
• Zinc: Fact sheet for health professionals. (2019).  https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/

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Embracing a plant-based diet

Focusing on whole foods from plant sources can reduce body weight, blood pressure and risk of heart disease, cancer and diabetes — and it can make your environmental impact more sustainable. Stanford Healthy Living instructor Dr. Reshma Shah offers simple ways to incorporate more plants into your diet.  

Your diet is one of the first places to start if you’re looking to manage your health and weight. Focusing on whole foods from plant sources can reduce body weight, blood pressure and risk of heart disease, cancer and diabetes — and it can make your environmental impact more sustainable.

But how do we embrace plants in our diets if we’re so accustomed to including meat and dairy as primary nutrition sources?

We spoke with Dr. Reshma Shah, a physician, plant-based eating advocate, co-author of “Nourish: The Definitive Plant-Based Nutrition Guide for Families” and Stanford Healthy Living instructor, about simple ways to incorporate more plants into your diet and the benefits this can provide for both you and the planet.  

Focus on whole, minimally processed foods.

People use many different terms to describe a plant-based diet, including vegetarian, lacto-ovo vegetarian, pescatarian, and flexitarian to name a few. The most restrictive is veganism, which  excludes all animal products, including meat, eggs and dairy. 

While there are health benefits to adopting a vegan diet, highly processed foods with little to no nutritional value, like Oreos or French fries, could still be a legitimate part of a vegan diet.

In contrast, a whole-foods, plant-based (WFPB) diet: 

• Emphasizes whole, minimally processed foods
• Limits or avoids animal products
• Focuses on plant nutrients from vegetables, fruits, whole grains, legumes, seeds and nuts 
• Limits refined foods like added sugar, white flour and processed oils 

Recommendations from organizations including the U.S. Dietary Guidelines for Americans, World Health Organization, American Diabetes Association and American Cancer Society tout the benefits of plant-based whole foods and caution against high amounts of red and processed meats, saturated fats, highly refined foods and added sugar. 

The vast majority of what nutritional experts are saying reflects the mantra made famous by Michael Pollen in his book “The Omnivore’s Dilemma” — eat food, mostly plants, not too much . 

Eating a plant-based diet helps the environment.

According to a report by the U.S. Food and Agriculture Organization, “The meat industry has a marked impact on a general global scale on water, soils, extinction of plants and animals, and consumption of natural resources, and it has a strong impact on global warming.” 

The meat and dairy industries alone use one third of the Earth’s fresh water , with a single quarter-pound hamburger patty requiring 460 gallons of water — the equivalent of almost 30 showers — to produce.

Reducing your meat and dairy consumption, even by a little, can have big impacts. If everyone in the U.S. ate no meat or cheese just one day a week, it would have the same environmental impact as taking 7.6 million cars off the road.

Plant-based diets prevent animal cruelty. 

Ninety-four percent of Americans agree that animals raised for food deserve to be free from abuse and cruelty , yet 99% of those animals are raised in factory farms, many suffering unspeakable conditions . 

If you would like to lessen your meat and dairy consumption due to animal welfare concerns but aren’t ready to eliminate all animal products from your diet, then you can start by taking small steps, like going meatless one day a week or switching to soy, almond or oat milk. Shah admits that initially she was not ready to give up animal products entirely. 

“I think it is a process and recommend that people go at the pace that feels comfortable for them.” 

Plant-based diets include all nutrients — even protein.

According to the American Dietetic Association, “appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, and for athletes.”

Shah says that there are a few key nutrients that strict vegans and vegetarians should keep in mind, including B12, iron, calcium, iodine, omega-3 fatty acids and vitamin D, but all of these can be obtained through plant-based foods, including fortified plant-based milks, fresh fruits and vegetables or supplemental vitamins, if needed. 

“I think the number one concern for people is that they won’t be able to get enough protein eating a plant-based diet. I also think that people widely overestimate the amount of protein they need.”

All plant foods contain the nine essential amino acids required to make up the proteins you need, and many vegetarian foods like soy, beans, nuts, seeds and non-dairy milk products have comparable amounts of protein to animal foods. 

“Ninety-seven percent of Americans meet their daily protein requirements, but only 4% of Americans meet their daily fiber requirements . I’ve never treated a patient for protein deficiency. If you eat a wide variety of foods and eat enough calories, protein should not be a concern.”

Savor the flavor of plant-based foods. 

Adopting a plant-based diet does not mean subsisting on boring, tasteless food. Shah enjoys incorporating flavorful, varied dishes from around the world, including Ethiopia, Thailand and her native India. 

To get started on your plant-forward journey:

• Start small: Start with adding a “Meatless Monday” to your meal plan and investigate one simple and delicious recipe to try each week. Once you have identified a few favorites, you can add them to your rotation and maybe go meatless one or two days a week. You can learn a few easy techniques to incorporate in many dishes, like roasting vegetables or blending quick and easy soups. 
• Change your plate proportions: Instead of giving up your meat-based protein completely, try to reduce the space it takes on your plate. Instead of a quarter-pound sirloin steak or a full serving of roasted chicken, try a vegetable-heavy stir-fry with a few slices of beef or a salad with chicken. Once your palate and mindset have adjusted to the smaller quantity of meat, try replacing it occasionally with plant-based proteins like tofu, seitan or beans.  
• Be prepared when dining out: If possible, try to examine the restaurant menu ahead of your meal, so you’ll arrive with a plan of what you can eat. Ask for the vegan options and don’t be afraid to request substitutions or omissions for your dish. Fortunately, with more people choosing a vegetarian lifestyle, many restaurants now provide tasty, meat-free options to their customers. 
• Share a dish: Bring a dish to share at a party or potluck; this will lessen your worries about food options. Let your host know ahead of time that you are planning on bringing a dish or, if that is not possible, be upfront and find out if any modifications can be made to accommodate your preferences. Often a simple solution can be found with a little advanced planning.
• Accommodate family members: It can be tricky when one family member is ready to commit to a new diet and lifestyle while others are not. Shah recommends approaching this situation compassionately and allowing for flexibility, if possible. Hopefully your family will be willing to support you even if they are not ready to make the same commitments. Communication is key, and Shah says that the conversation is over the minute someone feels judged, so try to look for points of compromise to reach an amicable solution. 
• Feeling satisfied: A diet of nothing but lettuce and vegetables will leave you feeling hungry and unfulfilled. Be sure to bulk up your meals with filling, fiber-rich whole grains, plant-based proteins and healthy fats. Plant-based meat substitutes like Beyond Beef, seitan and veggie burgers can also be a satisfying choice when you are craving your favorite meat-based comfort food.

Remember that small, consistent changes can add up to big benefits for your health and the planet. Treat yourself and others with compassion as you embrace this new lifestyle, and take time to enjoy the different flavors and textures you discover in your journey.

“It is a really delicious, healthful, sustainable and compassionate way of eating. It doesn’t have to be perfect. Just start simply, do what feels comfortable for you and your family, and don’t forget to celebrate the joy of eating and connection around food.” 

Dr. Reshma Shah will be teaching a plant-based online cooking class with Healthy Living this summer on Tuesday, July 13, from 4:00 – 5:30 p.m.

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518108/
• https://www.sciencedirect.com/science/article/pii/S2212371713000024 
•  https://www.portland.gov/water/water-efficiency-programs/save-water-home 
•   https://water.usgs.gov/edu/activity-watercontent.php  
• https://www.ewg.org/meateatersguide/a-meat-eaters-guide-to-climate-change-health-what-you-eat-matters/reducing-your-footprint/)  
• https://www.aspca.org/about-us/press-releases/aspca-research-shows-americans-overwhelmingly-support-investigations-expose 
•  https://www.sentienceinstitute.org/us-factory-farming-estimates
•  https://pubmed.ncbi.nlm.nih.gov/19562864/ 
•   https://www.ars.usda.gov/ARSUserFiles/8040053 0/pdf/0102/usualintaketables2001-02.pdf

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• v.9(5); 2023 May
• PMC10200863

Forty-five years of research on vegetarianism and veganism: A systematic and comprehensive literature review of quantitative studies

Gelareh salehi.

a Faculty of Economics and Business Administration, Universidad Pontificia Comillas. ICADE, Spain

b Business Management Department, Spain

Estela Díaz

Raquel redondo.

c Quantitative and Statistical Analysis Department, Spain

Associated Data

Data will be made available on request.

Meat production and consumption are sources of animal cruelty, responsible for several environmental problems and human health diseases, and contribute to social inequality. Vegetarianism and veganism (VEG) are two alternatives that align with calls for a transition to more ethical, sustainable, and healthier lifestyles. Following the PRISMA guidelines, we conducted a systematic literature review of 307 quantitative studies on VEG (from 1978 to 2023), collected from the Web of Science in the categories of psychology, behavioral science, social science, and consumer behavior. For a holistic view of the literature and to capture its multiple angles, we articulated our objectives by responding to the variables of “WHEN,” “WHERE,” “WHO,” “WHAT,” “WHY,” “WHICH,” and “HOW” (6W1H) regarding the VEG research. Our review highlighted that quantitative research on VEG has experienced exponential growth with an unbalanced geographical focus, accompanied by an increasing richness but also great complexity in the understating of the VEG phenomenon. The systematic literature review found different approaches from which the authors studied VEG while identifying methodological limitations. Additionally, our research provided a systematic view of factors studied on VEG and the variables associated with VEG-related behavior change. Accordingly, this study contributes to the literature in the field of VEG by mapping the most recent trends and gaps in research, clarifying existing findings, and suggesting directions for future research.

Non-standard Abbreviations

• • Vgt: Vegetarianism; Vgn: Veganism, M: Meat consumption; AHR: Animal-Human relationship; C: Cultured meat consumption; D: Diet; F : Food; P : Philosophy of life.
• • HL: Health; EN: Environment; AN: Animals; CL: Cultural & Social; SN: Sensory; FT: Faith; FN: Financial & economic; PL: Political; JS: Justice & world hunger.
• • A: Attitudes; M: Motivations; V: Values, T: Personality; E: Emotions; K: Knowledge; B: Behavior; I: Intentions; S: Self-efficacy or Perceived Behavioral Control; N: Networks; O: Norms; D: Identity; P: Product Attributes; F: Information.
• • CR: Correlational: M-CR: Mixed method study including Correlational section; EX: Experimental; EXC: Choice Experiment.

1. Introduction

Meat production contributes to animal suffering [ 1 ], environmental problems (loss of biodiversity, climate change, or water pollution) [ 2 ], and public health problems (zoonotic diseases such as COVID-19 and chronic non-communicable diseases such as type II diabetes) [ 3 ]. Consequently, there is an increasing interest in a dietary transition to reduce or exclude animal products [ [4] , [5] , [6] , [7] ]. Such dietary transitions would directly support goal 12 of the Agenda for Sustainable Development of the United Nations (2019), which is to “ensure sustainable consumption and production patterns” [ 8 ]. Adopting and maintaining vegetarian and vegan lifestyles are two of the most promising ways to achieve this goal [ 9 , 10 ].

VEG has a long history, dating back to ancient Greek philosophers, and can encompass various underlying approaches, including dietary behaviors, food and other product choices, social justice movements, and political activism [ 11 ]. Vegetarianism, as a philosophy of life, generally relates to the protection of non-human animals (hereafter referred to as “animals”), which, in practice, translates to a lifestyle that abstains from the consumption of all types of animal flesh, including meat (i.e., beef, pork), poultry (i.e., chicken, turkey), and fish and seafood [ 12 ]. Vegetarianism comprises several modalities: ovo-vegetarianism (accepts the consumption of eggs but not dairy products), lacto-vegetarianism (accepts the consumption of dairy products but not eggs), or lacto-ovo-vegetarianism (accepts the consumption of both eggs and dairy products) [ 13 , 14 ]. By contrast, veganism can be understood as a philosophy of life rooted in anti-speciesism, which, in practice, translates to rejecting the consumption of any product (or service) which involves the exploitation of an animal either in the context of food (meat, eggs, dairy, honey, gelatin), clothing (leather, silk), or any other form (entertainment and experimentation) as far as possible and practicable [ 15 , 16 ]. Veganism also promotes the production and consumption of alternatives free of animal use. To address vegetarianism and veganism (VEG), both of which avoid animal flesh products, many authors use the term “ veg*an-ism ” [ 8 , 17 ].

Over the last 50 years, the interest of consumers, entrepreneurs, and public institutions in the VEG phenomenon has grown [ 18 , 19 ]. VEG has increasingly spread worldwide [ 7 , 18 , 20 , 21 ]; for example, the number of individuals following some kind of VEG lifestyles is considered to have doubled from 2009 to 2016 [ 21 ], with 2019 being labelled “the year of the vegan” by The Economist [ 8 ]. The growing realization of the importance of these phenomena has also been reflected in academia, where studies on VEG have flourished in the last decade [ 7 ]. In this regard, VEG has rapidly expanded from philosophical and medical disciplines to other areas related to psychology, consumer behavior, and behavioral science [ 22 ]. One of the reasons for the increase in this research is related to the fact that, although VEG is seen as a promising avenue that brings a more ethical, sustainable, and healthier society, such a lifestyle transition is also seen as a challenge [ 23 , 24 ].

This extraordinary progression of scientific knowledge makes it advisable to know the current trends to map and have an overview of VEG research. Previous narrative literature reviews [ 11 , 22 , 25 ] have been of great relevance for this and have illuminated the way for researchers, practitioners, and public actors. However, owing to the increasing number of studies published in the last decade, it is highly recommended to update the knowledge and have a holistic view of the VEG literature. To achieve this, the most appropriate methodology is a systematic literature review [ 26 , 27 ]. This logic has been recently used to analyze the aspect of identity in veganism [ 28 ].

In this study, we conducted a systematic literature review in the VEG field to extend, complete, and update previous literature reviews. Specifically, our work principally focused on reviewing the quantitative studies in psychology, behavioral science, social science, and consumer behavior literature published in scientific journals from 1978 up to December 31, 2022, on VEG. A successful systematic literature review relies on straightforward research questions provided at the beginning of the process [ 27 ]; therefore, we articulated our objectives using the 5W1H [ 29 ], which explores a phenomenon from multiple perspectives based on the following questions: (1 W) “WHEN” refers to the period of the analysis and possible trends in VEG research; (2 W) “WHERE” focuses on the countries in which VEG studies have been conducted; (3 W) “WHO” refers to the journals in which VEG studies have been published; (4 W) “WHAT” refers to the different research streams and frames included in the VEG body of research; (5 W) “WHY” includes the reasons (environmental, health, or animals) that made VEG an essential topic for scholars to study; and (1H) “HOW” focuses on reviewing the different research methodologies and statistical analyses employed in the literature on VEG. Additionally, we added another question, “WHICH,” comprising the variables measured in the studies. Thus, we followed a 6W1H approach ( Fig. 1 ).

6 W & 1H approach applied to VEG literature.

This study contributes to the existing literature on VEG by mapping the state of the art, identifying trends and gaps in research, clarifying existing findings, and suggesting directions for future research. Our systematic literature review also highlighted the factors examined in VEG and the variables associated with VEG-related behavior change, thus playing an important role in advancing research on VEG. For practitioners, our study will help elucidate possible interventions and design more effective (marketing) campaigns to improve and promote the transition to VEG. Additionally, these interventions may be beneficial for private organizations and public authorities seeking to design policies to encourage fairer and more sustainable consumption and healthier lifestyles.

This article is organized as follows: In Section 2 , we outline the methodology. Next, we present the results of our analysis, which was performed using the 6W1H approach. In Section 4 , we discuss the main findings and future avenues of research. Finally, in Section 5 , we highlight the main contributions and managerial implications of the study.

The systematic search included articles up to December 31, 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used for reporting the methods of this systematic literature review [ 30 ]. The systematic literature review protocol included the following steps: (1) search strategy; (2) inclusion, exclusion, and selection criteria; and (3) data extraction.

2.1. Search strategy

The first step of conducting the systematic literature review was keyword design. Following the backward and forward search methods [ 27 ], we created a pool of terms related to VEG literature that represented the main objectives of the review and were included in the previous reviews [ 11 , 22 ]. Additionally, we screened through the preliminary keyword results in several non-medical articles that focused on VEG. The resulting keyword syntax designed was: title, abstract, and keywords = [(vegan* OR vegetarian* OR plant-based*)] AND [(diet* OR food* OR lifestyle* OR movement* OR activism*) OR (eat* OR choos* OR choice* OR behavio* OR chang* OR purchas* OR buy* OR pay* OR cosnum* OR substitut* OR lik* OR familiar* OR reject* OR avoid* OR accept* OR restrict* OR disgust* OR information*) OR (motiv* OR reason* OR attitude* OR intention* OR willing* OR belief* OR perception* OR value* OR identity* OR emotion* OR empathy* OR norm* OR social* OR knowledge* OR familiarity* OR gender*)].

We used Web of Science (WoS) for our search. WoS was preferred to other databases because it is the world's leading scientific citation search engine and the most widely used research database [ 31 , 32 ]. WoS has guaranteed scientific content, strict filtering, and anti-manipulation policies, and offers many resources for searching and collecting metadata [ [33] , [34] , [35] , [36] ]. In addition, WoS focuses on Social Sciences and Humanities (and less on Health Sciences) [ 37 ], which is more in line with the objectives of our study and covered all major journals relevant to our topic. However, it is worth mentioning that the final number of articles included in our systematic literature review resulted from reviewing the reference list of studies retrieved through WoS.

2.2. Inclusion, exclusion, and selection criteria

2.2.1. inclusion criteria.

The systematic search included articles up to December 31, 2022. During the initial search, 25,73 9 articles were identified through their titles, abstracts, and keywords ( Fig. 2 ). Once the articles were identified, we filtered the results following the inclusion criteria based on the following: (1) discipline: we included articles related to behavioral science, psychology, sociology, and business economics; (2) document type : we included only peer-reviewed articles; and (3) language: we only included articles written in English to ensure consistency and comparability of terms across the included studies. This was especially important as VEG is a recently emerging multi-disciplinary area.

PRISMA Flow diagram of the systematic literature review of quantitative VEG studies [ 30 ].

2.2.2. Exclusion criteria

Initially selected articles were removed based on the following: (1) research area : if their key focus was not on behavioral and psychological aspects of VEG. Thus, articles concerning medical issues (e.g., nutritional status or diseases), specific environmental problems (e.g., gas emissions or water), and technological challenges of food science (e.g., the chemical process of producing vegan products) were not included; (2) unit of analysis: studies with units of analysis different from individuals or households were excluded; and (3) methodology : we excluded qualitative studies. This decision was made because qualitative and quantitative approaches differ not only in their research techniques but, more importantly, in the ontological and epistemological perspectives they adopt [ 38 ]. Thus, we considered that separating quantitative from qualitative studies was advisable to gain a deeper knowledge on the issue. We focused on quantitative studies because there has been a more pronounced growth of quantitative studies and a greater interest in statistically measuring the factors that explain the adoption (or rejection) of VEG lifestyles. The selection protocol had no restrictions on sample characteristics (country and sex) and study setting (laboratory or restaurant).

This step left 203 articles for a full manuscript review. Finally, the reference list of articles was also reviewed, and 48 qualifying articles were added to the sample for data extraction. A total of 251 articles (307 studies, given that some articles included several studies) were recognized for data extraction. Initial screening for eligibility was performed by the three authors, each of whom reviewed one-third of the articles through the abstracts. To ensure consistency in the selection process, 5% of the articles were randomly assigned to a different author to perform an inter-reviewer reliability test [ 39 , 40 ]. The results indicated excellent agreement in this first step, as 96.5% of the articles were equally identified by the reviewers, and Cohen's kappa was 0.91.

2.3. Data extraction

A coding template was designed in Excel to extract specific data to answer the 6W1H questions. Information on WHEN (year of publication), WHERE (country of the sample), and WHO (journals) was coded directly. The coding of WHAT was more complicated; therefore, we designed a coding protocol to perform a preliminary content analysis of the data following the recommendations of Welch and Bjorkman [ 41 ]. We initially started pilot coding 30 articles, considering two main research streams : veganism (Vgn) and vegetarianism (Vgt). The coding of these research streams was based on the provided definitions of VEG and explained earlier. In this understanding, some scholars addressed their objective on vegetarianism (Vgt) and considered veganism (Vgn) as a sub-category of vegetarianism (Vgt). In these studies, we coded the stream as Vgt-Vgn. It should be noted that some studies also used the term “plant-based” in their studies; however, when reviewing the work, we observed that the authors used that term as a synonym for vegetarianism, veganism, or both. Therefore, following the same approach for vegetarianism, we coded these studies in the corresponding group of currents. In the second round of coding, we identified that veganism and vegetarianism were also studied simultaneously (Vgt-Vgn) as well as with other phenomena: meat consumption, animal-human relationship, and cultured meat consumption; we called these three new streams secondary streams . In total, coding was performed with seven streams.

To provide more nuanced information concerning WHAT, a further coding step was conducted to reclassify the studies not only concerning the streams but also the following three frames: (1) food, referring to specific products; (2) diet, referring to dietary practices; and (3) philosophy of life, referring to a social movement and lifestyle, focusing on the characteristics of the person consuming VEG products or following a VEG diet or philosophy of life. As mentioned previously, sometimes, these three frames were analyzed in combination (e.g., food and diet). Overall, five research frames were identified. To ensure the decision in coding, each article was scanned for keywords using an agreed a priori system. The manuscripts were also re-checked, ensuring accuracy and agreement, and differences were discussed with the third researcher to reach inter-coding agreement, which provided a measure of consistency.

For WHY, we were interested in coding the reasons that scholars considered VEG as an important subject to be studied. Reasons from existing literature were classified into two broad categories: central and peripheral reasons. Central reasons included health issues, concern for animals, and environmental sustainability. Peripheral reasons comprised justice and world hunger; faith, religion, and spirituality concerns; sensory factors; cultural and social aspects; financial and economic aspects; and political concerns.

WHICH aimed to explore the variables measured in the VEG studies (attitudes or values). Finally, for HOW, we collected information contained in the methodology section of the articles regarding the type of study, sample, and statistical techniques. Thus, we collected information regarding the unit of analysis (individuals vs. objects), type of data (longitudinal vs. cross-sectional), data sources (secondary vs. primary), number of data sources, data collection methods (archival data, or surveys), and the year of data collection. Information on the sample comprised the size, country, mean age, percentage of female participants, racial or ethnic origin of respondents, and VEG orientation of respondents (vegetarian or vegan). Additionally, we checked whether the sample was representative of the corresponding general population. Subsequently, the studies were classified into non-experimental or correlational or experimental (choice experiment, or within-subject and between-subjects).

We also collected information regarding the dependent and independent variables, number of constructs, and the theoretical frameworks and scales used to measure them (especially if the scale used was designed ad ho c to study the VEG phenomenon). Finally, regarding the statistical techniques, we compiled information about the analyses and techniques used (e.g., t-tests, correlation tests, ANOVA, MANOVA, regressions, SEM, and latent class analysis). We also checked for the use of normality tests (if required), scale validation, moderation, and mediation tests, as well as whether the study was aware of the possible threat of common method effects (if required), social desirability, or other potential biases. The criteria for coding HOW included the guidelines of the Effective Public Health Practice Project.

3.1. WHEN were the VEG studies conducted?

The final 307 studies covered a period from 1978 to December 31, 2022. The characteristics of the studies are summarized in Table 8 in Annex. Eighty-four percent of the studies included in this review were published in the last ten years (see Fig. 3 ). The findings provide reasonable evidence that academic interest in VEG research has grown exponentially. Exploring the evolution in more detail, we observed three peaks in the number of publications. First, in 1999 the number of publications per year increased from one to four; second, in 2015, the number of publications increased again to approximately more than ten articles per year. Finally, the most significant evolution occurred in 2019, when the number of publications doubled (from 14 to 35). The trend also grew steadily until 2021; in 2022, this number increased to 61 studies. Most of the publications in 2021 were related to the special issue of Appetite journal, titled “The psychology of meat-eating and vegetarianism.”

Count of VEG topic studies published from 1978 up to December 31, 2022.

3.2. WHERE were the VEG studies conducted?

In terms of regional concentration, research was focused on developed countries, mainly in the US (33%), the UK (10%), Germany (6.5%), Australia (3.5%), Canada (3.3%), and Spain (3.3%). It should be noted that many studies (12%) included data from more than one country, but these international samples were mainly from the US and the UK. A simultaneous analysis of WHEN (publication year) and WHERE (country) also showed that the pioneer countries were the US, UK, Australia, and Canada. Other countries’ quantitative inquiries on VEG started in 2000 by studies in New Zealand, Finland, and the Netherlands. Geographical orientations became more widespread from 2015 onward ( Table 1 ).

Simultaneous analysis of WHERE and WHEN.

3.3. WHO published the VEG studies?

The reviewed articles were published in 92 different journals ( Table 2 ). Regarding the number of articles published in each journal, the relevance of Appetite was evident, with 21.8% of all articles reviewed published in this journal. This was followed by Food Quality and Preference (6.8%), Sustainability (4%), and British Food Journal (3%).

Journals and their research areas.

3.4. WHAT has been studied in VEG research?

3.4.1. streams of veg.

As it is shown in Table 3 , we discerned the following seven streams: vegetarianism and veganism (Vgt-Vgn); vegetarianism (Vgt); veganism (Vgn); vegetarianism, veganism, and meat consumption (Vgt-Vgn-M); vegetarianism and meat consumption (Vgt-M); vegetarianism, veganism, meat consumption, and cultured meat consumption (Vgt-Vgn- M -C); and vegetarianism, veganism, animal-human relationship (Vgt-Vgn-AHR) . The research mainly focused on Vgt-Vgn (30%), Vgt-Vgn-M (17.6%), Vgt (13%), and Vgt-M (12%).

WHAT streams have emerged in the VEG quantitative studies? a .

Vgt: Vegetarianism; Vgn: Veganism; M: Meat consumption; AHR: Animal-Human relationship; C: Cultured meat consumption.

By simultaneously analyzing WHAT (streams) and WHEN (publication years), we noticed that the first quantitative study on the Vgn stream was conducted in 2010 ( Fig. 4 ). Academic interest in Vgn research grew steadily, except for a decline in 2018. However, Vgt studies started decades earlier, in 1981. The Vgt stream was the pioneer in the quantitative approach of VEG, but this trend was not continuous; we observed a gap from 2010 to 2016 in the Vgt stream. Interestingly, in 2020 there was a peak in research focused on Vgn and Vgt streams. Finally, we observed an evolutionary increase of studies in the Vgt-Vgn- M -C stream.

When and what (streams).

3.4.2. Frames of VEG

By analyzing the different conceptualizations of VEG in research, we observed that 56% of studies framed it as diet, 24% as consumption of VEG food products, and 6% as the philosophy of life. Some studies also considered VEG as a combination of two frames: diet and consumption of VEG food products (6.5%) and diet and philosophy of life (6%). To get a more accurate picture of the focus of researchers, we crossed the streams with the frames of VEG. As shown in Table 4 , framing the VEG phenomenon as diet was more present in Vgt stream (70.7%), followed by Vgt-Vgn-M (68.5%) and Vgt-M (67%) streams. Expectedly, framing VEG as food was more prevalent in Vgt-Vgn- M -C (79%). Through the simultaneous evaluation of seven streams and five frames, we found a total of 35 distinct research categories on VEG. This analysis showed that 19.5% of studies focused on Vgt-Vgn. D stream, followed by Vgt-Vgn-M. D (12%), Vgt- D (9%), and Vgt-M. D (8%). It is noteworthy to mention that in four research categories (Vgt-Vgn-M. P , Vgt-Vgn-M. DP , Vgt-Vgn- M -C. P , and Vgt-Vgn-AHR. DF ) , we did not find any published articles.

VEG has been studied in WHAT frames through the streams?

Vgt: Vegetarianism; Vgn: Veganism; M: Meat consumption; AHR: Animal-Human relationship; C: Cultured meat consumption; D : Diet; F : Food; P : Philosophy of life.

The publication of five VEG research frames over the years is shown in Fig. 5 . Studying VEG through the diet frame increased over the years, with peaks in 2021 (28 studies) and 2015 (11 studies). However, this interest decreased to 15 studies in 2022. By contrast, there was a relatively high number of studies analyzing VEG in the food consumption frame, with two peaks in 2022 (35 studies) and 2020 (10 studies). It is worth noting that the number of studies in other frames was relatively small and did not seem to follow any temporal pattern.

When and what (frames).

3.5. WHY have researchers found it relevant to study VEG?

In Section 2.3 , we undertook a classification of the relevance of studying the VEG phenomenon as cited in the reviewed articles. Our analysis yielded two distinct groups: central and peripheral reasons. The former comprised concerns related to health, environmental issues, and animal welfare. The latter encompassed a diverse range of additional factors, including cultural and social considerations, sensory preferences, faith, financial and economic implications, political concerns, and world hunger. For clarity, we will discuss these nine motives below according to the order of importance in which they appear in the reviewed studies (see Fig. 6 ).

WHY it is important to study VEG.

3.5.1. Central motives

Among the reasons identified in the studies to justify the importance of studying VEG, health concerns (83%) had the highest presence. Exploring this further, we found that many articles referred to the health aspect of VEG as the respondents’ motivation [ 42 , 143 ]. Some authors explained the positive effect of VEG on the human body by mentioning specific benefits, such as reducing cholesterol, blood pressure, or risk of diabetes, as well as reducing the incidence of cancers, heart disease, and hypertension [ 2 , 3 , 63 , 144 ]. More recently, a body of research interested in a more holistic view of health considered VEG options as an essential contributor to well-being and quality of life [ 8 , 53 , 115 ]. However, a minority referred to the potential adverse physical health effects, such as nutritional deficiencies (vitamin B12, zinc, or iron) if a well-planned VEG diet is not followed [ 53 ], or mental health risks, such as risks of stigmatization, discrimination, or feelings of embitterment [ 48 , 91 , 168 ]. Simultaneous analysis of WHY and WHAT showed that health considerations were the most frequently cited concern across all streams. Notably, more articles focused on Vgn (93%) and Vgt-Vgn (89%). Table 5 summarizes the convergence of these motives in each stream.

WHY did scholars considered VEG important to be studied?

HL: Health; EN: Environment; AN: Animals; CL: Cultural & Social; SN: Sensory factors; FT: Fait; FN: Financial & economic; PL: Political; JS: Justice & world hunger.

In the reviewed literature, there was a significant presence of referring to the environmental benefits of VEG (75%). Diversity in arguments and approaches was also observed when analyzing the environmentalist discourse. Some authors emphasized specific impacts; for example, they discussed how replacing animal-based diets with VEG diets could help reduce greenhouse gas emissions [ 9 , 60 , 67 ] and soil degradation [ 19 , 62 , 66 ], and tackle current problems related to air, soil, and water pollution [ 214 ], biodiversity loss [ 62 ], as well as climate change [ 61 ]. Nevertheless, most studies addressed the environmental benefits of VEG quite loosely, using terms such as a “sustainable” strategy [ 183 ] or alternatives to lessen the impacts of the current animal agriculture. Similarly, some authors mentioned that VEG alternatives comply with the United Nations 2030 Sustainable Development Goals. However, the terms “vegan” or “vegetarian” are absent in these goals [ 8 ]. Analyzing the frequency of environmental concerns among different streams indicated that environmental issues were the most frequently cited concern in the Vgt-Vgn- M -C stream with a prevalence of 89.6%, followed by 87% in the Vgt-Vgn-M stream and 83% in the Vgt-M stream. This suggests that environmental issues may have a significant role in encouraging studies transitioning from meat consumption to cultured meat consumption.

Approximately two-thirds of the reviewed studies (67%) included varied arguments on animal-related concerns. In some instances, animal-related concerns were considered a central aspect of VEG discourse, while in others, they were only tangentially referenced. References to animal concerns appeared implicit and subsumed under the general term of “ethical” [ 64 , 170 ] or “moral” reasons [ 117 , 212 ]. Conversely, in other instances, the phenomenon of VEG appeared firmly rooted in the animal rights or animal protection movement [ 255 ]. Another example of these differences was found when researchers discussed the drivers of following, adopting, or consuming VEG options. For example, some researchers emphasized the positive aspects of VEG for animals; we found references to “compassion toward animals” [ 54 ], “animal advocacy” [ 258 ], “affection toward animals” [ 255 ], or “animal welfare” [243,263 ] . In contrast, other researchers highlighted the detrimental effects of the current animal agriculture on animals and how VEG alleviates this negative impact. These studies often used expressions such as “animal suffering” [ 117 ], “animal exploitation” [ 260 ], or “animal slaughter” [ 81 ].

Notably, we also found diverse philosophical approaches adopted in the studies to defend VEG. Some research aligned strongly with welfarist positions [ 114 , 145 , 215 ], while others aligned with abolitionist or animal rights perspectives [ 60 , 116 , 256 ]; to a lesser extent, anti-speciesism discourses were also incorporated [ 15 ]. The presence of animal concerns significantly depended on the stream. Expectedly, in the Vgt-Vgn-AHR stream, animal considerations were found in all of the studies, followed by 86% in the Vgn stream.

3.5.2. Peripheral motives

In this category, distinguished three sub-groups according to the relevance with which they appeared in the reviewed research. In the first sub-group, we found cultural and social, and sensory motives, each present in 33% of the studies. Cultural and social factors included the influence exerted by certain people or groups on an individual's decisions about their VEG choices. Specifically, studies focused on analyzing the impact of people's close networks, mainly families or peers [ 21 ], and online vegan discussion groups [ 19 ]. Cultural and social factors were mainly observed in the Vgt stream (41%).

For sensory reasons we referred to consumer or producer concerns about the sensory aspects of VEG alternatives, which are typically related to VEG foods (i.e., taste, texture, odor, or appearance) [ 99 , 117 , 143 ]. Sensory reasons were primarily observed in the Vgt-Vgn-AHR (50%) and Vgn (46%) streams.

In the second place, we found references to financial and economic, and faith reasons, present in 25% and 22% of the articles, respectively. VEG studies citing financial and economic reasons were relatively scarce. These typically covered cost savings from the consumer's perspective [ 174 ]. These concerns were primarily mentioned in the studies on the Vgt-Vgn- M -C stream (72%), which was expected owing to the growing market of VEG products. Faith motives included both religious [ 109 , 231 ] and spiritual beliefs [ 45 ]. Generally, these reasons were typically studied as drivers of VEG choices [ 68 , 100 ]; however, these concepts require further exploration. Faith reasons appeared mainly in the Vgt-Vgn-AHR stream (37%).

Finally, we found that political, and justice and world hunger arguments [ 130 , 153 ] had a much lower presence in the studies; specifically, they were each mentioned in only 12% of the articles. Political aspect of the VEG referred to connections to other social movements and other political issues beyond animal protection; in this sense, we found references to claims for women's or LGBTQ rights [ 258 ]. In most cases, these political issues were neither defined nor explained in depth. Political motives were primarily observed in the Vgn (20%) and Vgt-Vgn-AHR (16%) streams. Justice and world hunger concerns referred to the world hunger problem [ 13 , 205 ] and various arguments on how VEG can improve food availability or exacerbate social inequality and injustices [ 161 , 164 ]. However, these arguments require more specificity and detail. They were mainly explored in Vgn studies (36%). In general, we observed that 50% of studies were commonly mentioned in HL-EN-AN ( Table 8 in Annex).

3.6. WHICH variables were analyzed in VEG studies?

Before proceeding to a detailed study of the variables examined in the literature, it should be noted that only 29.6% of the studies used theoretical frameworks to measure the variables under examination. In this group of studies, we found that 33.7% used the Theory of Planned Behavior (TPB) [ 270 ]; 8.6% of the studies used the Unified Model of Vegetarian Identity [ 271 ]; 7.6% applied human values theory [ 272 ]; 7.6% employed the Transtheoretical Model [ 273 ], and 4% used Social Dominance Orientation [ 274 ]. The usage of these theories across the seven streams of studies is summarized in Table 6 . It is worth noting that approximately 11% of the reviewed studies applied other theoretical frameworks than the five most prevalent ones.

Most extensively researched theories in each stream of VEG studies.

For the specific variables analyzed in the literature, we grouped them into five categories: psychological dispositions, cognitive-affective variables, behavioral constructs, social determinants, and situational variables. Table 7 summarizes the convergence of these variables and constructs in each stream; as illustrated, the prevalence of the variables depended on the stream in question, and in many of them, some variables were overlooked. For clarity, we analyzed each construct group according to the order of frequency in which the variables appeared in the studies.

WHICH variables has been measured in each stream of VEG quantitative studies?

A: Attitudes; M: Motivations; V: Values, T: Personality; E: Emotions; K: Knowledge; B: Behavior; I: Intentions; S: Self-efficacy or Perceived Behavioral Control; N: Networks; O: Norms; D: Identity; P: Product Attributes; F: Information.

3.6.1. Psychological dispositions

Psychological dispositions included variables related to attitudes, motivations, values, and personality traits. Attitudes , understood as perceptions, and opinions on VEG-related issues, applied to different aspects and 67% of the studies measured attitudes. This variable was mainly constructed as attitudes toward animals [ 15 , 136 , 167 ], meat [ 137 , 141 ], and VEG lifestyles [ 54 , 108 ]. In addition, some studies measured attitudes in the context of justification strategies for non-VEG lifestyle choices [ 258 ]. Some authors differentiated between positive, negative, and neutral attitudes [ 23 , 49 ], but most studies did not make such distinctions and referred to attitudes as a uniform construct. Similarly, they did not differentiate between cognitive, affective, and conative aspects recognized in the consumer behavior literature [ 275 ]. Attitudes were primarily found in studies on Vgt-Vgn-AHR (87%), followed by those focusing on Vgt-Vgn- M -C (79%).

Regarding motivations , 39% of the reviewed studies were interested in studying the reasons that encouraged consumers to practice VEG (i.e., becoming a VEG, following a VEG diet, consuming VEG products). Particularly, studies focused on analyzing three types of motivations. First, studies with a strong hedonistic character, which were related to personal health, sensory appeals, and economic considerations [ 43 ]. Second, studies with a strong altruistic, ethical [ 8 , 151 ], or even spiritual character (e.g., Buddhism) on the adoption of VEG choices [ 68 , 261 ]. Here, authors differentiated between interest in animal protection (protecting animals from unnecessary suffering), environmental conservation (climate change and global warming), and human rights (the relationship between world hunger and the dedication of resources to livestock production rather than agriculture) [ 2 , 19 , 113 , 208 ]. Third, studies with a strong social character, in which we detected an interest in studying the effect of following VEG diets due to living with VEG family members or friends [ 53 , 114 ]. It is worth mentioning that some studies took a broader approach to motivations and studied them abstractly as a general concern to pursue their choice of VEG, but without delving into the type of motivation that affected the decision-making [ 13 ]. The interest in measuring motivations was observed, especially in studies on Vgn (53%), Vgt (46%), and Vgt-M (51%).

Values , understood guiding principles [ 42 ], were present in 21% of the studies. They were typically measured with extensively validated instruments, such as the Social Dominance Orientation scale [ 274 ], [e.g., 74 , 104 , 136 , 213 ], the Theory of Basic Human Values of Schwartz [ 271 ], [e.g., 114 ], or Altemeyer's Authoritarianism scale [ 276 ], [e.g., 67,74]. These studies concluded that the likelihood of practicing VEG was associated with greater endorsements of liberalism, universalism, and left-wing ideology [ 54 , 164 , 165 ]. As more specific values related to the VEG, we found speciesism measurement, understood as the belief in the supremacy of humans over animals [ 19 , 94 , 136 , 213 ]; in these cases, the use of the Dhont et al.‘s [ 277 ] speciesism scale stood out. Similarly, we found the measurement of carnism, namely, the belief system that supports the consumption of certain animals as food [ 132 ]; in this case, the variable was measured using Monteiro et al.‘s [ 278 ] scale. It should be mentioned that many scholars considered values as motivations (i.e., referring to religious reasons as religious values) [ 64 ]. Values were observed the most in the Vgt-Vgn-M stream (25%).

Our data also showed that 12% of studies focused on measuring personality traits [ 3 , 109 ]. These studies employed the Eysenck Personality Questionnaire [ 45 , 113 ], the Big Five test [ 69 , 84 , 87 ], and the Food Neophobia (reluctant to try or eat novel food) scale [ 52 , 172 ]. Personality traits were observed in the Vgt-Vgn stream (19.5%), followed by the Vgt stream (12%).

3.6.2. Cognitive-affective variables

Cognitive-affective variables referred to variables associated with the emotional responses to and knowledge regarding VEG. Regarding emotions , many scholars acknowledged that VEG lifestyles and choices were affectively charged [ 279 , 280 ]. Despite this recognition, emotions were only present in 23% of the studies in this field. The emotions associated with VEG lifestyle and choices included disgust (toward meat) [ 96 ], sensory (dis)liking VEG foods [ 96 , 143 ], guilt related to diet consistency or pet food choice [ 96 , 268 ], anger [ 144 ], shame [ 213 ], fear [ 74 ], and affect or empathy responses (the capacity to feel what others are experiencing) [ 3 , 15 , 47 , 136 , 194 ]. Most previous studies did not use validated instruments to measure these emotions. Notable exceptions were found in the assessment of meat disgust and meat enjoyment, which was mainly measured using the disgust scale [ 3 ] and the meat attachment questionnaire [ 84 , 213 ], respectively. Emotional concerns were more prevalent in the Vgt-Vgn-AHR (41%) and Vgt-M (32%) streams.

Knowledge was measured in 17% of studies and referred to the familiarity with VEG products [ 143 , 227 ], VEG diet [ 13 , 171 ], and the understanding of the relevance and impacts of VEG on health [ 103 ] and environment [ 202 ]. Knowledge was explored primarily in studies focused on Vgt-Vgn-M (24%).

3.6.3. Behavioral constructs

In the behavioral constructs, we observed behaviors, intentions, and self-efficacy. The measurement of behaviors was present in 72% of the reviewed studies, primarily involving self-reported food consumption habits [ 2 , 3 , 167 ]. In many cases, the inclusion of this construct was intended to complement and compare the self-reported status as vegan, vegetarian, or neither [ 2 , 167 ]. Most of these scales measured general food consumption behaviors. The Food Frequency Questionnaire [ 4 , 90 ], the Food Choice Questionnaire [ 131 ], and purchase frequency [ 8 , 183 , 251 ] were the most commonly used instruments to measure this variable. Notably, two articles advanced the measurement of behaviors using observational measurement via experimental designs [ 126 , 136 ]. Another pattern we observed in our review was the interest in the temporal aspect in which behaviors are performed. In this regard, although most studies focused on current consumption behaviors, some highlighted the relevance of past behaviors [ 110 ] and the duration for which individuals practiced VEG lifestyles [ 2 , 18 , 64 , 141 , 165 , 260 ]. Additionally, a few studies measured more than one behavior; as sometimes, all behaviors were directly related to food consumption. For example, Crimarco et al. [ 145 ] measured participants’ overall food consumption frequency, adherence to the vegan diet, and restaurant-related behaviors. In other studies, measured behaviors were related more to health, such as alcohol consumption [ 113 ] or adequate nutritional intake [ 192 ], and more rarely, to animal-related behaviors [ 128 , 256 , 268 ]. This variable appeared most frequently in the Vgt-Vgn-M (85%) and Vgn (76%) studies.

Intentions were included in 25% of the studies. In the reviewed articles, they were measured as the willingness to cut down on meat [ 205 ], try VEG foods [ 143 ], adopt a VEG lifestyle [ 190 , 226 ], being VEG [ 255 ], or continue practicing a VEG lifestyle in the future [ 2 ]. Some studies specified a time frame (e.g., next month, next two years) in their questions [ 49 , 255 ]. For example, in Wyker and Davison's [ 108 ] study, intention was measured by asking for agreement to the statement, “ I intend to follow a plant-based diet in the next year .” To assess intentions, some studies applied the Transtheoretical Model [ 13 , 108 ], but primarily drew on TPB [ 13 , 15 ]. Among the different streams, measuring intention was predominant in the Vgt-Vgn- M -C (65%), Vgn (33%), and Vgt-Vgn-M (27%).

Self-efficacy was only present in 8% of the studies, and referred to personal control, perceived ability, and perceived level of ease or difficulty in following the VEG lifestyle [ 2 , 108 , 200 ]. Self-efficacy was predominantly based on TPB, referred to under the term Perceived Behavioral Control. This construct was adapted to the VEG context by several scholars [ 15 , 60 , 190 ]. This variable was most prevalent in studies on Vgt-Vgn-M (13%). Interestingly self-efficacy was not observed in Vgn and Vgt-M streams.

3.6.4. Social determinants

The social determinants included variables related to the influence of social ties or networks , as well as identity and social norms to act (or not) in accordance with VEG. Social network was present in 20% of the studies and measured through a variety of constructs, such as group membership [ 136 ], having VEG friends and family [ 8 ], or participation in a social movement [ 165 ]. An analysis of its presence in the different streams showed that it was most prevalent in research on Vgn (43%) and Vgt-M (29%). None of the reviewed studies measured social networks in the Vgt-Vgn- M -C stream.

Our analysis showed that identity was present in 11% of the studies and was analyzed using different approaches, such as political [ 165 ], social [ 18 , 127 , 131 ], or self [ 142 , 190 ] identities. A notable recent construct was that of “dietarian identity” [ 14 , 18 , 132 , 179 ], as measured by the Dietary Identity Questionnaire [ 271 ]. Dietarian identity refers to individuals' self-image with regard to consuming or avoiding animal-based products, regardless of their actual food choices [ 2 , 166 , 168 ]. This latter qualifier is important to consider in VEG studies, because people's actual diets and their self-reported dietary identity may appear inconsistent. For example, people who self-identify as a “vegan” might still consume animal products occasionally, while other people may strictly avoid animal products but not consider themselves to be “vegan.” [ 166 ]. This variable stood out in studies on the Vgt-Vgn-M stream (20%), followed by Vgt (19%).

Finally, another way in which social determinants appeared in the literature was through the social norms , which referred to the social pressure received from society and significant others to adopt (or reject) VEG alternatives [ 60 ]. Specifically, we found this variable in 8% of the studies. In some cases, it referred to imperative (perceived social pressure) and descriptive norms (the number of VEG people in the participant's circle) [ 141 , 205 ]. However, it was more commonly understood as subjective norms, close to the operationalization in TPB (as the extent to which participants consider that significant people in their lives think they should follow or avoid a VEG lifestyle) [ 2 , 15 ]. Social norms were mainly analyzed in the Vgt-Vgn-AHR (16%) and Vgt-Vgn-M (14%) streams.

3.6.5. Situational variables

This group included product attributes and informational signals regarding VEG. Present in 22% of the studies, research on product attributes focused on two types of attributes: (1) extrinsic attributes, such as labeling, nutrition information, functional claim, visibility, affordability, accessibility, promotion, or availability [ 21 , 86 , 242 ]; and (2) intrinsic attributes, such as texture, taste, smell, visual appearance, color, or size [ 143 , 231 ]. Product attributes were observed dominantly in studies on Vgt-Vgn- M -C (55%), followed by Vgt-Vgn-M (27%), and Vgt-Vgn (21%).

Our analysis identified that 19% of the studies focus on analyzing the effect of different informational signals on raising awareness of VEG [ 144 ], promoting VEG products [ 52 ], and eliciting cognitive or emotional responses to VEG information [ 52 ]. For example, some studies focused on measuring the effect of exposure to specific ethical or environmental messages [ 170 , 182 , 258 ], documentaries [ 165 ], or campaigns [ 174 ] on the perception of VEG alternatives. Another group of studies measured the impact that different VEG food images had on consumers [ 5 , 52 , 188 ]. It is worth noting that these studies were often experimental and were conducted online or in laboratory settings [ 3 , 170 ]. Informational signals were mainly explored in studies in Vgn (33%), followed by Vgt-Vgn- M -C (31%) and Vgt-Vgn-AHR (29%) streams.

As discussed above, research has focused on examining a wide range of variables to understand the VEG phenomenon. To summarize, Fig. 7 depicts a conceptual map of the relationships explored in the reviewed studies. It is important to note that the aim of this map was not to provide a conclusive explanatory model, but rather to show how the relationship between the variables has been conceptualized in the literature and illuminate future avenues of research. The map schematically proposes that situational variables elicit certain emotional responses, which in turn can affect knowledge and attitudes toward VEG. Likewise, attitudes, a variable closely related to individuals’ values and beliefs, have a direct impact on intention, which may originate from different motivations. Intentions are assumed to be directly affected by social networks, social norms and self-efficacy, and indirectly affected by identity and personality traits. Finally, the direct and indirect effect of all these variables translates into actual behavior. All these variables translate into actual behavior.

Conceptual map of measured variables in quantitative VEG studies.

3.7. HOW the VEG studies were conducted?

All 307 studies in this review were quantitative, as per the inclusion criteria; however, we found that the studies included different research designs. Sixty-eight percent of the studies were conducted based on correlational or non-experimental design (collecting data based on surveys). Among the non-experimental studies, eight were mix-method designs and included both qualitative and quantitative data, for which we coded the quantitative part ( Table 8 in Annex). Thirty-two percent of the studies were experimental. Among these, 17 were choice experiments. In addition to varied research designs, we observed different types of information regarding the data collection, sample characteristics, and statistical analysis. We discuss these three aspects below.

3.7.1. Data collection

Regarding the type of studies conducted, 87% were based on cross-sectional data (vs. 13% longitudinal data) [ 138 , 162 , 204 ]. It is worth mentioning that only 47.5% of the studies reported the year of data collection. Among the experimental studies, 31% dealt with between-participant and 9% with within-participant designs. Furthermore, the settings of these experiments were mainly online [ 156 , 159 , 269 ], in research laboratories [ 135 , 209 ], or in restaurants or cafeterias [ 186 ]. Manipulations varied depending on the research objective, but many involved the use of exposures to different stimuli, such as informational text messages [ 110 , 114 , 187 ], images of food [ 5 , 86 , 111 , 167 ], or manipulated menu design [ 110 , 125 , 186 ].

Analyzing the data sources utilized in the reviewed studies revealed that 92% of the studies relied on primary sources, 7% employed secondary data, and only a limited number used both primary and secondary data [ 2 , 21 , 231 ]. The secondary data sources were mainly obtained from national panels, such as the US National Health Survey [ 53 ], the Swiss Food Panel [ 4 , 176 ], the UK Integrated Household Survey [ 204 ], and the German Socioeconomic Panel [ 87 ]. An examination of the methodologies used for collecting primary data revealed that a large number of studies relied on a single source (89.5%). Relatedly, the most commonly used method was self-reported data. Only 13% of the studies supplemented the self-reported method with additional information such as body measurements [ 101 , 113 , 164 ], brain responses [ 135 , 167 ], or implicit attitudes [ 3 , 43 , 111 , 209 ].

Of the studies that used primary data, most employed surveys to collect data; among these, the use of Likert scales (ranging from 1 to 5) and yes-or-no questions was prominent. Although the reliability of the scales was addressed in general terms (mainly through Cronbach's alpha), the validity of the scales was often not considered. In this sense, factor analyses (exploratory and confirmatory) were only used in 14% of studies as the most appropriate techniques to test the validity of the scales. It should be mentioned that although many complex concepts related to VEG were investigated, 65% of the studies did not use constructs but single variables. Moreover, most variables did not result from the operationalization of the constructs from a specific theoretical framework.

3.7.2. Sample

The unit of analysis in 98% of the studies was the individual respondents; the rest focused on other units, such as households [ 183 , 204 ]. Additionally, we found that sample sizes ranged from 10 [ 101 ] to 143,362 [ 204 ] and that 11% of the studies used 100% student samples. The measurement of some socio-demographic variables was present in all the studies as necessary information to describe the sample; however, not all studies presented all or the same type of information. Regarding sex, the sample consisted of both male and female participants, except for six studies conducted exclusively with females [ 112 , 122 , 172 , 185 , 197 ]. The data also showed that female participation was generally higher than male participation, with an average of 64% of the total sample. Among those that provided this data, the percentage of female participants was higher than 50% of the total number of cases in 72% of the cases. Concerning the ethnic composition of the sample, we found that only 8% of the studies provided information on ethnicity, 74% of the respondents from the samples (on average) were Caucasian and that one study was conducted entirely on African-Americans [ 230 ]. In terms of age, 40% of the studies did not report the mean age of respondents and 98% used adults as a sample, meaning that only a few studies focused on children [ 12 , 44 , 140 , 141 , 215 ]. Regarding the VEG status of the respondents, 54% of the studies were conducted on VEG and non-VEG participants [ 42 , 205 , 230 ], 25% on only VEG participants [ 18 , 45 , 177 ], and 20.84% on only non-VEG participants [ 13 , 110 , 143 ].

3.7.3. Statistical techniques

The most used statistical techniques in order of relevance were ANOVA (or ANCOVA and MANCOVA; 44%), chi-square test (21%), t-tests (17%), and Mann-Whitney test (3%). A few studies adopted a more predictive approach by running a model with the corresponding dependent and independent variables. In these cases, the most used techniques were OLS regression (16%) [e.g., 41], logistic regression (15%) [ 110 ], or SEM/PLS models (9.7%) [ 15 , 23 , 255 ]. Very few studies performed additional analyses, such as mediation (8%) [ 144 ], and moderation (2%) [ 15 ]. Some other studies tried to classify individuals according to different characteristics and primarily used statistical techniques, such as cluster (2%), [e.g., 84, 90, 151,193] or latent class (1%) [ 202 , 231 ] analyses.

However, normality was assumed in most cases; only 14% of all studies (experimental and non-experimental) reported (non)compliance with the normality assumption [ 15 , 42 , 144 ]. Additionally, very few studies (20%) warned of the risk of certain or potential bias, especially the risk associated with Common Method Effects, such as selection or social desirability biases. Of these few studies, only some performed any statistical technique to ensure that bias did not threaten the results; they mainly mentioned this it in the limitations.

4. Discussion

This systematic literature review shed light on the development of quantitative peer-review studies on VEG published up to December 31, 2022, within psychology, behavioral science, social science, and consumer behavior domains. The 6W1H analytical approach was chosen as a guide for analysis to have a holistic view of the literature and capture its multiple angles. This approach aimed to answer the questions of WHEN, WHERE, WHO, WHAT, WHICH, WHY, and HOW the research on VEG was published. To the authors’ knowledge, this is the first systematic literature review conducted on VEG. In this section, we highlight and discuss the most relevant findings and gaps we drew from the study.

In line with the increasing worldwide attention to VEG alternatives and with other authors' observations [ 7 , 11 , 22 ], our study confirmed that researchers’ interest in studying VEG has grown, especially in the last ten years. The results of our review showed exponential growth of publications in recent years; specifically, the average number of publications, which increased from one in the 1980s and 1990s to 61 in 2022.

The present study also showed that such interest is particularly robust within English-speaking Western countries; in this regard, we identified a geographical gap in the literature, as the studies reviewed were mainly concentrated in the US, [e.g., 2,13,143] and the UK [e.g. Refs. [ 14 , 21 , 49 ]]. This geographical dominance, which could be due to multiple causes beyond the scope of this article (e.g., greater number of researchers, potential for research funding, availability of technology, and trajectory of veganism), is a major constraint to advancing knowledge on VEG, given that both human-animal relationships and food consumption are strongly influenced by cultural factors [ 281 , 282 ]. Accordingly, several criticisms have emerged, claiming that research on VEG is racially biased and strongly appropriated by Western culture [ 165 ].

As for the journals in which research on VEG was published, we observed an interesting change of focus. The study on this phenomenon was born with a strong link to journals focused on animal rights and activism as VEG was clearly presented as a manifestation of a philosophical, ethical, and political stance that questions the anthropocentric position of human beings with respect to the rest of the animals. However, our review clearly showed the preference of authors in recent years to publish their research in journals highly focused on analyzing the relationship between behavioral change and nutritional or dietary choices. In this sense, we found that Appetite was the journal chosen most frequently to publish quantitative studies on VEG. This evolution indicates that the rationale for healthy and sustainable eating in VEG research has become more prominent than ever, while the implications these alternatives have for animals have been diluted. In line with this, we found that the Vgt-Vgn. D approach of research dominated the literature, while the most prominent gap in the literature was of VEG as a life philosophy or social movement. This was illustrated by the arguments expressed by researchers to defend the relevance of studying VEG, the main driver being health, followed by animal protection, environmental concerns, and other considerations (religion or spirituality, world hunger, social factors, and sensory appeal). Taken together, our results add evidence to a recent concern in the literature about the depoliticization of VEG in society (especially in veganism) that is fading from its antagonistic origins [ 283 ]. The spread of VEG in academic endeavors, as well as in business and personal practices, seems more often motivated by personal health reasons (understood in terms of physiological health) than by ethical considerations.

Focusing on the objectives and methodological approach of the studies reviewed, we highlighted five main gaps. First, through the overview obtained on the topic, we realized a notable lack of research on consumer behavior change or the process of transitioning to VEG. We identified only a few studies that analyzed self-reported lifestyle changes [e.g. Ref. [ 177 ]], especially measuring actual behavior change over time [e.g. Ref. [ 174 ]].

Second, among the variables used, we noted a preference for studying rational and conscious content over emotions, feelings, and the unconscious mind in human behavior, [e.g. Refs. [ [284] , [285] , [286] ]]. To illustrate, although there was a strong interest in studying attitudes toward meat substitutes [ 231 ], VEG individuals [ 75 ], or VEG diet [ 144 ], it was very rarely accompanied by an adequate definition and measurement of the cognitive, affective, and conative dimensions widely recognized in the literature [ 287 , 288 ]. Despite plenty of measures developed to examine the psychology of meat-eating [ 22 , 289 ], such as carnism inventory [ 278 ], meat attachment [ 60 ], or moral disengagement to meat [ 213 ], we found gaps in the tools used to measure the variables examined in VEG studies. Although some well-known scales were incorporated, such as the disgust scale [ 290 ], or personality traits [ 291 ], in general, the instruments used to measure the constructs were often not validated in the literature but constructed ad hoc for the specific research being conducted. Very little progress has been made in the development of constructs and scales tailored to VEG. The exceptions to this are the Dietary Identity Questionnaire [ 271 ], Vegetarian Eating Motives Inventory [ 116 ], and Vegetarianism Treat Scale [ 277 ].

Third, we observed that in the field of VEG, data-driven research was more prominent than theory-driven research. This is an important shortcoming, given that data-driven methods are less likely to offer clear theoretical perspectives to help analyze results [ 292 ]. We agree with Schoenfeld [ 293 ] that “theory is, or should be, the soul of the empirical scientist” [p [ 105 ]]. Theory-driven approach is especially important in quantitative research owing to its deductive logic based on “a priori theories.” [ [ 294 ] p312]. Thus, the lack of anchoring research on VEG in theoretical frameworks is another of the gaps detected in our review.

Fourth, the rapid growth and innovation of software, together with the increased availability of diverse data sources, have expanded analytical capabilities and methodological options adapted to each topic. However, our research showed that such advances had very little impact on the field of VEG studies (at least in the non-medical VEG literature), as the richness of the data was not large (mainly self-reported and cross-sectional studies); descriptive and correlational statistical techniques remained the most used analytical approaches, highlighting another gap in VEG literature. However, one innovation that was recently incorporated in VEG research and is worth mentioning is brain response measurements. These types of measurement methods were rarely used [ 167 ] as the field is still dominated by self-reported surveys, as mentioned above. Nevertheless, the contrasting results of self-reported versus physiological responses in Anderson et al.‘s [ 167 ] study highlighted the importance of using multiple data sources when attempting to analyze people's responses and to inform the dietary patterns required in dietary scales, as they provide a richer and better picture of consumer behavior.

Fifth, with respect to the samples used in the VEG studies, it is pertinent to address two important matters. On the one hand, vegans and vegetarians were often merged and studied as a unified group. However, a growing body of research demonstrated that vegans and vegetarians not only present differences in terms of behavioral and attitudinal characteristics (such as identity profiles [ 93 ], value orientations [ 42 ], and cognitive ability [ 113 ]), but that the motivations driving the adoption of their lifestyles (animal protection, environment, and health) also influence how the person experiences the VEG alternative. On the other hand, studies were expected to clearly indicate the composition of their sample according to socio-demographic variables; however, our review showed that this practice was not always met, especially regarding ethnicity, sex, and age, variables highly relevant to food, ethical consumption, and animal protection [ 15 , 144 ]. Analyzing the studies that provide such information would reveal that research involving minors and culturally diverse groups [ 54 ] is notably scarce. However, considering that the adoption of VEG has traditionally had a philosophical foundation [ 1 , 16 , [295] , [296] , [297] ] and that certain responses to it are learned by social contagion [ 298 ], different mechanisms depending on the age of the participants and their cultural setting are expected. In addition, we detected a very narrow and traditional approach to the concept of “gender” in that most studies used the dichotomous categories of male and female. This approach does not align with the existing discourse on diversity and gender fluidity [ 299 ] and could hinder progress in deepening our understanding of the relationship between VEG, gender issues, and animal advocacy [ 300 , 301 ].

5. Conclusion

5.1. contribution.

Our systematic literature review contributes to the literature by providing an overview and mapping the growing body of research on VEG, which allowed us to clarify existing findings as well as identify trends and gaps in existing research. Using the 6W1H approach, we offered a novel lens for examining the topic and a systematized mapping of the variables examined by researchers when studying VEG, and more specifically, the new and emerging factors that influence VEG-related behavior change.

Three main conclusions can be drawn from our research. First, our study highlighted the growing body of research on VEG. However, Anglophone countries dominate the research in this field, which may lead to a certain bias in the analysis of the phenomenon. In this regard, some scholars and practitioners have raised some criticisms, claiming that VEG is racially biased and strongly appropriated by Western thought.

Second, reflecting holistically on the evolution of VEG research, it appears to be shifting from a political-philosophical positioning to an individual consumption choice or dietary option. This shift in framing is relevant because it may have important implications for its progress in the sense that the approach we adopt as researchers, when investigating any phenomenon or idea, influences its conceptualization and development in society [ 302 ]. After all, “meanings do not naturally or automatically attach to the objects, events, or experiences we encounter, but arise through culturally mediated interpretive processes” [303 p. 144].

Third, we observed that the field of VEG is still dominated by data-driven research; however, to gain a richer and deeper understanding of the VEG phenomenon and advance the discipline, studies should be grounded in theory. In addition, it is advisable to increase the richness of the data, quality of the measurements, and sophistication of the statistical techniques applied by broadening the variables examined, extending the populations under investigation, and improving the methods of analysis.

5.2. Academic and managerial implications

Our comprehensive overview and mapping of VEG research can benefit scholars in different ways. On the one hand, by highlighting and identifying the latest gaps, this study can be useful in leading and guiding researchers toward topics, the unit of analysis, and methods to advance VEG research and, thus, move the discipline forward. In this sense, our study aimed to show “the path” so that by understanding our current status, we can plan the future of our research. On the other hand, as academics, we need to select the journal that we consider most appropriate for disseminating our work. To this end, we usually apply two central criteria [ 39 , 304 ]: (1) the suitability of the topic studied that is of interest to an audience of academics and practitioners; and (2) the prestige of the journal, a variable that contributes to the credibility and diffusion of our findings. In some cases, this decision may be a simple task; however, it is more complicated in novel fields studied from multiple disciplines and approaches, as is the case of VEG. Therefore, we expect that this study will assist researchers in this regard.

The systematized mapping of measured variables can also help practitioners and public policymakers design innovative and more effective interventions aimed at fostering more just, healthy, and environmentally sustainable societies. Considering that the lack of awareness and confusion about the different VEG options acts as barriers to their adoption, this study can help clarify the different perspectives on the phenomena. This, in turn, can help public and private institutions involved in animal rights, environmental sustainability, and public health in designing educational programs tailored to the idiosyncrasies of the target group. In this sense, future policies could develop educational activities targeting adults and younger generations. In addition, interventions have focused on VEG food choices or reducing meat consumption as stand-alone strategies so far, but future interventions could be more effective if designed through nudging strategies.

From the perspective of understanding consumer behavior, marketers of VEG foods could benefit from our study by having a deeper understanding of consumers' motivations, goals, and objectives toward VEG products, which, in turn, will serve to better segment markets and offer products more tailored to their needs and desires. Marketers can also encourage the consumption of VEG products; for example, by promoting the adoption of short-term actions, such as the “Lundi-Vert” campaign in France or “Veganuary” in the UK, aimed at increasing people's familiarity with these products and improving their perception of them. In addition, the studies reviewed showed the role of monetary incentives on VEG products, which could be used in future policies to increase the willingness to buy them.

5.3. Limitations

Systematic literature reviews present potential shortcomings, especially in the selection process of the publications that constitute the corpus, which could exclude some relevant information. In this sense, although WoS is a very comprehensive and reputable database, we cannot exclude the possibility that some articles may have been excluded from our selection and analysis. Additionally, to provide greater homogeneity and consistency to the study, we focused on articles published in English and in peer-reviewed academic literature. Future research could complement our study with those published in other languages (e.g., Spanish, French, German, or Chinese) as well as in books, conferences, or “gray literature” [ 305 , 306 ].

Another difficulty inherent to the systematic literature review is related to the process of coding the content of the studies that constitute the corpus to be analyzed. As mentioned in the Methodology, in our study the coding was agreed upon and performed by the three researchers. However, it cannot be ruled out that the position of the three investigators may sometimes differ from that of the readers or authors of the studies reviewed.

5.4. Recommendations and future research avenue

In accordance with the research gaps identified, we propose some avenues for future research to contribute to the advancement of VEG research. First, to address geographical gap, we consider it important to broaden the scope of studies to other countries (e.g., Eastern regions or Spanish-speaking countries), and to conduct more cross-cultural research [e.g. Ref. [ 224 ]]. We also recommend that future research focus on the analysis of the less examined VEG frames (e.g., as a philosophy of life or social movement), and explore the sociological and political aspects or dimensions of the phenomenon to have a more comprehensive understanding of it, especially in the case of veganism, which goes far beyond eating habits. However, we also believe that research attempts on VEG will be more fruitful if they incorporate separate (or comparative) analyses of the different streams, as well as the study of attitudes and behaviors toward animals.

To overcome the lack of research on VEG, we encourage scholars to adopt a more dynamic perspective on the phenomenon by incorporating the temporal factor into the design of their studies. This can be achieved, for example, by conducting longitudinal and experimental studies, and by using the so-called “stage theories” in their research. This approach will make it possible to observe how different constructs develop over time and how they influence the process of rejecting or adopting VEG. It may be of great interest for future literature reviews could focus on other topics related to VEG that were only tangentially explored in our work (e.g., cultured meat, pescatarianism, flexitarianism). Additionally, it would be interesting to synthesize the manifold advantages and disadvantages from multiple angles (ethical, environmental, social, and health) of adopting the different VEG options.

In addition, to advance research knowledge, theoretically underpinning future research attempts on VEG will provide a richer and deeper understanding not only on the topic under analysis but also the theoretical framework used in the research. In this regard, it would also be desirable to be more innovative (e.g., including gender diversity and fluidity) [ 299 ] and to show greater diversity (e.g., in terms of age and race) with respect to the population analyzed. This recommendation is more than timely, considering the current overrepresentation of some groups of participants.

In terms of methodology, our research showed that there is much room for improvement in terms of data collection, the variables studied, the tools used to measure these variables, and the statistical techniques used for subsequent analysis. Broadly speaking, future research should consider the following recommendations: (1) use diverse sources to collect information so that studies can combine observed, self-reported, and behavioral data, for which digital technologies can be implemented; (2) examine new variables and use scales and instruments previously validated in the literature to obtain good reliability and validity of the measures to capture the proposed concepts and avoid biases; and (3) conduct complementary analyses to delve deeper into the topic under investigation, using powerful statistical techniques to go beyond simple descriptive and correlational analyses and pave the way for deeper causal analyses.

As stated on multiple occasions, the present article aimed to review the existing quantitative literature to date on VEG. The large number of studies selected and the great heterogeneity observed among them (related to objectives, data, and streams) highlighted the complexity of performing a meta-analysis. Nevertheless, in future research, we will consider the possibility of performing a meta-analysis to deepen the effect of the relationships between some of the variables revealed in our study. Additionally, future reviews can focus on qualitative studies to examine whether their results are similar to ours.

The general conclusion we reach is that, despite the boom in research on VEG in recent years and the great and laudable efforts made to date by researchers, the study of the phenomenon is still in its early stages. This conclusion offers good news: the path of VEG research is still ahead of us and there is sufficient scope for innovation.

Author contribution statement

All authors listed have significantly contributed to the development and the writing of this article.

Funding statement

This study has been funded by Universidad Pontificia Comillas, reference number PP2021_10.

Data availability statement

Declaration of competing interest.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper

Acknowledgments

The authors would like to thank four anonymous reviewers for their thoughtful feedback. The authors also thank Dr. Ben De Groeve and Dr. Jeffrey Soar for their helpful comments on an earlier draft of this manuscript.

6W1H of VEG quantitative studies in psychology, behavioral science, social science and consumer behavior domains of WoS (1978–2022)

Vgt: Vegetarianism; Vgn: Veganism; M: Meat consumption; AHR: Animal-Human relationship; C: Cultured meat consumption; D: Diet; F: Food; P:Philosophy of life.

HL: Health; EN: Environment; AN: Animals; CL: Cultural & Social; SN: Sensory; FT: Faith; FN: Financial & economic; PL: Political; JS: Justice & world hunger.

A: Attitudes; M: Motivations; V: Values, T: Personality; E: Emotions; K: Knowledge; B: Behavior; I: Intentions; S: Self-efficacy or Perceived Behavioral Control; N: Networks; O: Norms; D: Identity; F: Information; P: Product Attributes.

CR: Correlational or non-experimental: M-CR: Mixed method study including Correlational section; EX: Experimental; EXC: Choice Experiment.

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Article Contents

Introduction, evidence acquisition, metabolic and molecular mechanisms associated with vegetarian diets, evidence from prospective studies, evidence from randomized clinical trials, potential health risks of vegan and vegetarian diets, the importance of consuming healthy vegetarian diets, conclusions, supplementary data, declarations, data availability.

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Vegetarian and vegan diets: benefits and drawbacks

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Tian Wang, Andrius Masedunskas, Walter C Willett, Luigi Fontana, Vegetarian and vegan diets: benefits and drawbacks, European Heart Journal , Volume 44, Issue 36, 21 September 2023, Pages 3423–3439, https://doi.org/10.1093/eurheartj/ehad436

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Plant-based diets have become increasingly popular thanks to their purported health benefits and more recently for their positive environmental impact. Prospective studies suggest that consuming vegetarian diets is associated with a reduced risk of developing cardiovascular disease (CVD), diabetes, hypertension, dementia, and cancer. Data from randomized clinical trials have confirmed a protective effect of vegetarian diets for the prevention of diabetes and reductions in weight, blood pressure, glycosylated haemoglobin and low-density lipoprotein cholesterol, but to date, no data are available for cardiovascular event rates and cognitive impairment, and there are very limited data for cancer. Moreover, not all plant-based foods are equally healthy. Unhealthy vegetarian diets poor in specific nutrients (vitamin B12, iron, zinc, and calcium) and/or rich in highly processed and refined foods increase morbidity and mortality. Further mechanistic studies are desirable to understand whether the advantages of healthy, minimally processed vegetarian diets represent an all-or-nothing phenomenon and whether consuming primarily plant-based diets containing small quantities of animal products (e.g. pesco-vegetarian or Mediterranean diets) has beneficial, detrimental, or neutral effects on cardiometabolic health outcomes. Further, mechanistic studies are warranted to enhance our understanding about healthy plant-based food patterns and the biological mechanisms linking dietary factors, CVD, and other metabolic diseases.

A comparison of healthy vegetarian diets vs. unhealthy vegetarian diets. HbA1c, glycosylated haemoglobin; LDL-C, low-density lipoprotein cholesterol.

Plant-based diets have become increasingly popular thanks to their purported health benefits and more recently for their positive environmental impact. 1 There are different types of plant-based diets, but in this review, we will focus our attention primarily on vegan (100% plant-based), lacto-ovo vegetarian (i.e. plant-based except for dairy products and/or eggs), and pesco-vegetarian or pescatarian (i.e. plant-based except for fish and seafood with or without eggs and dairy) diets. All vegetarian diets exclude meat (e.g. beef, pork, lamb, venison, chicken, and other fowl) and related meat products.

According to the American and Canadian Dietetic Associations, appropriately planned and supplemented vegan and lacto-ovo vegetarian diets are nutritionally adequate and suitable for individuals in all stages of the life cycle and may provide health benefits in disease prevention and treatment. 2 , 3 These statements are supported mainly by cross-sectional and prospective studies with accumulating data from a limited number of clinical randomized trials. Moreover, not all plant-based foods are equally healthy. Vegetarian diets rich in refined flours, hydrogenated oils, high-fructose corn syrup (HFCS), sucrose, artificial sweeteners, salt, and preservatives have been shown to increase morbidity and mortality ( Figure 1 ). 4–6 The purpose of this article is to review succinctly the current knowledge on the effects of vegetarian diets on the risk of developing some of the most common and costly chronic diseases, including cardiovascular disease (CVD), obesity, type 2 diabetes mellitus (T2DM), hypertension, dementia, and cancer, and to discuss what is known about its metabolic and molecular adaptations and effects.

Metabolic effects of healthy and unhealthy vegetarian diets. MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; LDL-C, low-density lipoprotein cholesterol; TG, triglycerides.

We searched EMBASE, MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), and PubMed, from inception until 20 September 2022. Hand searches of reference lists of reviews, protocols, and clinical trial registries (ClinicalTrials.gov) were performed to supplement searches. Search terms included diet , plant-based , vegetarian , vegan , cardiovascular , cardiovascular diseases , diabetes , T2DM , hypertension , cancer , dementia , and cognitive function . The authors of the ongoing trials were contacted to retrieve preliminary findings and full manuscripts. Both basic science and clinical research studies were reviewed. The published clinical reports that we reviewed included epidemiologic studies, case-control studies, and randomized controlled trials. Quality of data was assessed by taking into account publication in a peer-reviewed journal, number of individuals studied, objectivity of measurements, and techniques used to minimize bias.

The precise mechanisms by which well-designed and balanced vegetarian or vegan diets may exert their beneficial effects in lowering the risk of coronary heart disease (CHD) and possibly cancer and dementia are under scrutiny. Many factors have been hypothesized to play a role, including (i) lipid-lowering effect; (ii) glucose-lowering, insulin sensitizing, and hormonal effects; (iii) protection against oxidative stress, inflammation, and hypertension, and (iv) production of intestinal microbial metabolites influencing metabolic and immune health ( Figure 2 ).

Cardioprotective mechanisms of healthy vegetarian diets. Multiple nutritional effectors of a healthy vegetarian diet modulate important metabolic, hormonal, and immune factors associated with the development of cardio- and cerebrovascular diseases. K, potassium; Mg, magnesium; Se, selenium; NaCl, sodium chloride; SCFA, short-chain fatty acids; LDL-C, low-density lipoprotein cholesterol; VLDL, very-low-density lipoprotein; GI, glycaemic index; BCAA, branched-chain amino acid; TMAO, trimethylamine N -oxide.

Lipid-lowering effect

Several factors can explain why vegetarians have significantly lower levels of plasma cholesterol, especially when they consume minimally processed plant foods. Vegetarians do not consume meat, and vegans also avoid milk, butter, and dairy. Beef, lamb, and pork contain high levels of saturated fat and cholesterol and minimal amounts of polyunsaturated fats; even lean cuts of beef may contain up to 4.5 g of saturated fat per 100 g serving. One-cup serving of whole milk contains 4.5 g of saturated fat, and one tablespoon of butter contains 102 kcal and 7 g of saturated fat. In contrast, one tablespoon of olive oil contains 119 kcal and only 1.9 g of saturated fatty acids. Epidemiological studies have shown a strong linear relationship between saturated fat intake, plasma cholesterol levels, and CHD. 7 , 8 Substituting 5% of energy intake from saturated fatty acids with a similar quantity of energy from polyunsaturated fats, monounsaturated fats, or carbohydrates from whole grains is associated with a 25%, 15%, and 9% lower risk of CHD, respectively. However, when saturated fats are replaced with carbohydrates from refined carbohydrates, the risk of developing CHD increases substantially. 9 Data from randomized clinical trials have demonstrated a cause–effect relationship; 10–12 replacing saturated fat with vegetable polyunsaturated fats decreases CHD by 30% that is similar to the reduction induced by statin therapy. 13 Seeds and nuts are excellent sources of polyunsaturated fatty acids and contain soluble and insoluble fibres and sterols that are known to lower cholesterol. 14 Epidemiological studies suggest that frequent nut consumption can reduce the risk of CHD by 40%–60%. 15 Data from randomized clinical trials confirm that consuming a diet rich in nuts, viscous fibres from oats, barley, psyllium, and plant sterol ester–enriched margarine can reduce plasma low-density lipoprotein (LDL) cholesterol by 13%. 16 Moreover, vegetarian diets rich in whole grains, legumes, nuts, and dried fruits can provide ∼15 g of dietary fibre per 1000 kcal. In a 4 month weight loss double-blind, placebo-controlled clinical trial, overweight or obese men and women who received a daily supplement of soluble fibre (3 g Plantago ovata husk and 1 g glucomannan) experienced a significant greater drop in LDL cholesterol than those in the placebo group. 17 Dietary fibres and phytosterols reduce the (re)absorption of cholesterol and bile acids in the small intestine, thus resulting in an increased LDL uptake by the liver. 18 , 19 Moreover, foods rich in dietary fibre and with low glycaemic index can lower insulin production and increase the levels of short-chain fatty acids produced by fibre fermentation, which have both been shown to inhibit cholesterol synthesis. 19

Glucose-lowering, insulin sensitizing, and hormonal effects

Vegetarians, and especially vegans, tend to have lower body weights than omnivores. In a survey of the American Adventists population, average body mass index (BMI) in omnivores, semi-vegetarians, lacto-ovo vegetarians, and vegans was 28.3, 27.3, 26.1, and 24.1 kg/m 2 , respectively. 20 Although consuming a vegetarian diet does not require counting calories, results from clinical trials demonstrate that people randomized to a vegetarian diet tend to lose more weight than those consuming Western diets. 21 , 22 Preclinical, epidemiological, and clinical studies suggest that distinct dietary interventions may promote atherogenic and metabolic fat depot mobilization differently. 23 The high-fibre and water content and lower energy density of vegetables, legumes, and whole grains may in part explain this effect. Consumption of diets rich in dietary fibre induces gastric distention, delays gastric emptying, and prevents large fluctuations in postprandial blood glucose. 24 Short-chain fatty acids produced by the intestinal microbial metabolism of resistant starch and oligosaccharides of minimally refined plant foods induce satiety by inhibiting gastric emptying through incretins such as peptide-YY and glucagon like peptide-1 that markedly reduce blood glucose and body weight in randomized clinical trials. 25–27 Moreover, whole-food vegan and vegetarian diets may result in fewer bioavailable calories, and it is well known that calorie restriction with adequate nutrition in humans exert a powerful effect in improving glucose tolerance, insulin sensitivity, and many other cardiometabolic, inflammatory, and hormonal factors implicated in the pathogenesis of CVD and cancer. 28–30 As reviewed elsewhere, 28 , 31 excessive (central) adiposity causes insulin resistance, dysregulation of sex hormones and insulin-like growth factor-1 (IGF-1) signalling, low-grade chronic inflammation, and immune dysregulation of natural killer cells and stromal tumour-infiltrating lymphocytes, limiting antitumour responses. Compensatory hyperinsulinaemia together with increased bioavailability of oestradiol, testosterone, and IGF-1 promotes cell proliferation and genomic instability through activation of the PI3K/AKT and p66 shc pathways, which have been associated with increased risk of multiple cancers, including breast, endometrial, prostate, and colon cancer. 28 , 31

Additional mechanisms mediating the insulin sensitizing and glucose-lowering effects of healthful minimally processed vegetarian diets are the low glycaemic index/load and the lower intake of protein, especially of sulphur and branched-chain amino acids. Estimated daily protein intake for omnivores in Western societies is ∼90–100 g of which ∼70%–85% is animal proteins rich in methionine, valine, leucine, and isoleucine. Results from both population and randomized experimental diet interventions show that high protein intake, especially of branched-chain amino acids, is associated with an increased prevalence and risk of developing pre-diabetes and T2DM. 32 Diabetes risk increases by 20%–40% for every 10 g of protein consumed in excess of 64 g per day. 33 , 34 Interestingly, in some studies, high intake of animal protein, but not of plant protein, was associated with the higher risk of developing T2DM. 32 , 34 , 35 In weight loss trials of obese women, high protein intake (1.3 g kg −1 per day including two servings of a whey protein isolate) completely prevented the markedly improved insulin sensitivity observed in women consuming a normal protein diet (0.8 g kg −1 per day) who lost the same amount of body weight and visceral and liver fat. 36 Furthermore, dietary branched-chain amino acid (BCAA) restriction in mice recapitulates many of the beneficial effects of protein restriction observed in rodents and humans, including reduced adiposity, increased glucose tolerance, and increased energy expenditure, but not increased FGF21 levels. 37 In contrast, high dietary intake of BCAA increases platelet activation and arterial thrombosis risk by enhancing tropomodulin-3 propionylation. 38 Consistently, data from two trials demonstrated that consuming high-protein diets (comprising dairy and meat products and whey protein supplements) cause a reduction in insulin sensitivity and an associated increase in blood insulin levels. 39 , 40 In an another trial of patients with T2DM, high consumption of chicken, fish, eggs, low-fat milk, and cheeses prevented the expected improvements in glucose metabolism and insulin sensitivity induced by a 2 month weight loss intervention. 41 High-protein diets, particularly those rich in leucine, can also play a role in promoting atherosclerosis and plaque instability in mice by exacerbating macrophage apoptosis induced by atherogenic lipids, via mTORC1-dependent inhibition of mitophagy and accumulation of dysfunctional mitochondria. 42

Protection against oxidative stress, inflammation, and hypertension

Well-designed vegetarian diets rich in vegetables, whole grains, legumes, nuts, seeds, and fruits provide a wide range of vitamins (vitamin C, vitamin E, and beta-carotene), minerals (selenium), and phytochemicals (tannins, phenols, alkaloids, and flavonoids) with xenohormetic effects. 43 Numerous large observational studies suggest that an inverse relationship exists between antioxidant and polyphenol intake and the risk of developing diabetes, CVDs, cancer, and possibly dementia. 44 High intake of dietary antioxidants and phytochemicals may reduce the risk of developing atherosclerotic plaques because it triggers adaptive modulations of stress-response enzymes and receptors that prevent lipoprotein oxidation, endothelial dysfunction, and immune activation. 45 , 46 Findings from large prospective studies suggest that dietary patterns with higher inflammatory potential are significantly associated with higher level of systemic and vascular inflammation, an unfavourable lipid profile, and ultimately with a higher incidence of CHD and stroke. 47 Dietary patterns with lower inflammatory potential are those that favour foods rich in dietary antioxidants and vegetable fibre (e.g. green leafy and dark yellow vegetables, whole grains, fruit, tea, and coffee) and avoid red and processed meat and refined liquid and solid carbohydrates. 48–52

Diets rich in vegetable fibre, potassium, and magnesium and low in sodium, especially when associated with a healthy body weight and regular endurance exercise training, markedly lower systolic and diastolic blood pressure, 53–56 which is a powerful risk factor for the development of CHD, heart failure, stroke (both ischaemic and haemorrhagic), and dementia. Indeed, data from epidemiological and genetic causal inference studies show that elevated systolic blood pressure, insulin resistance, and excess adiposity at midlife are important risk factors for developing cognitive impairment and Alzheimer’s disease because they cause endothelial dysfunction and vascular damage to the brain, particularly at the level of perforating cerebral arteries and neurovascular units. 57 , 58 In contrast, reduction of systolic blood pressure prevents and/or slows progression of cognitive impairment to dementia. 59

Modulation of gut microbiome function and effect on human metabolic state

Diet composition has a pervasive effect in modulating systemic microbiome biology. Metagenomic data show that specific nutrients, especially insoluble fibre, and protein intake deeply influence gut microbiota structure and function and the production of a growing list of metabolically active molecules. 60 , 61 For instance, unlike vegetarians diets, Western diets rich in red meat, eggs, and cheese contain higher concentrations of nutrients such as choline and L-carnitine that increase the microbial production of trimethylamine N -oxide (TMAO). 62 , 63 Animal and human studies have shown that higher levels of circulating TMAO increase the risk of developing CVD, independent of traditional cardiometabolic risk factors, by inducing vascular inflammation and platelet activation. 64 , 65 In contrast, healthful plant-based diets rich in whole grains, legumes, and nuts can markedly increase the intake of dietary fibres, key fermentable substrates for the proliferation of Bacteroidetes and the production of short-chain fatty acids such as acetate, propionate, and butyrate. 66 , 67 Experimental animal data indicate that these microbial metabolites exert powerful blood pressure–lowering and immune-modulating effects, via activation of specific G-protein–coupled receptors expressed on enteroendocrine and intestinal immune cells. 61 , 68 Long-term consumption of vegetarian diets has also been associated with more phylogenetic biodiversity of stool microbiota; in contrast, multigenerational exposure to Western diets poor in ‘microbiota-accessible carbohydrates’ causes an extinction of specific bacterial lineages, which impairs immune function and maturation, and increases the risk of developing a range of metabolic, inflammatory, allergic, and autoimmune diseases. 69 , 70 Interestingly, data from the DIRECT-PLUS trial show that a calorie-restricted and (almost) red-meat-free version of the Mediterranean diet enriched in plant-based proteins (Green-MED diet) is superior to the classical Mediterranean diet in improving the 10-year Framingham risk score and in lowering waist circumference, intrahepatic fat, LDL cholesterol, diastolic blood pressure, C-reactive protein, and HOMA insulin resistance. 71 These cardiometabolic beneficial effects were partially mediated by a major shift in the composition and function of the gut microbiome, including enrichments in the genus Prevotella and reductions in the genus Bifidobacterium with associated inhibition in BCAA biosynthesis and up-regulation of BCAA degradation enzymatic pathways. 72 This is crucial because a growing body of evidence show that reprogramming microbial functions through long-term adherence to healthier plant-rich diets has profound effects in shaping physiologic response to specific nutrients, to calorie restriction, and to other features of host biology that are instrumental in promoting health and longevity. 73 , 74

Prospective epidemiological studies have suggested that consuming vegetarian diets might have protective effects against the development of obesity, diabetes, hypertension, CHD, several type of cancers, and, most recently, cognitive decline. Whether these associations are causal deserves careful consideration of all available evidence, including data from other types of studies.

Hypertension

Findings from observational studies suggest that people consuming vegetarian and vegan diets have lower blood pressure than people eating Western diets, even after adjusting for age, sex, and BMI. 75 Compared with Seventh-day Adventist who are omnivores, those who follow a vegetarian diet have lower blood pressure and a reduced incidence of hypertension, independent of body weight and sodium intake. 76 Data from multiple observational studies including three large prospective American cohort studies suggest that consuming red meat and poultry is associated with an increased risk of hypertension, independent of vegetable, whole grain, and fruit intake. 77

Type 2 diabetes mellitus

Several studies suggest protective effects of vegetarian diets in the prevention of T2DM. Findings from the Adventist Health Study-2 (41 387 participants free of diabetes followed for 2 years) found that, even after controlling for multiple confounding factors, vegetarians had a significantly lower risk of T2DM than omnivores. 78 The most apparent protective effect was for vegan diets with a 62% risk reduction, followed by semi-vegetarian (51% reduction) and lacto-ovo vegetarian (38% reduction) diets. The Adventist Mortality Study and Adventist Health Study followed a cohort of 8401 individuals for more than 17 years. 79 After controlling for weight and weight change, long-term adherence to a diet incorporating weekly meat intake was associated with a 38% higher risk of T2DM compared with a vegetarian diet with no meat intake. This finding are supported by data from a joint analysis of three large cohort studies (the Health Professionals Follow-up Study, n = 26,357; the Nurses’ Health Study, n = 48,709; and the Nurses’ Health Study II, n = 74,077) confirming a statistically significant association between red meat consumption and an increased risk of T2DM ( P < .001 for all studies). 80 After adjusting for initial BMI and concurrent weight gain, a daily increase of > 0.5 servings of red meat was linked with a 30% higher risk of T2DM. In contrast, reducing red meat intake by > 0.5 servings/day was associated with a 14% lower risk of T2DM.

Cardiovascular disease

A joint analysis of five prospective studies including 76 172 individuals has shown a lower CHD mortality in vegetarians than in omnivores: 34% less in lacto-ovo vegetarians and pesco-vegetarians and 26% lower in vegans. 81 Another meta-analysis of 7 studies (124 706 participants) report a 29% decreased mortality from CHD in vegetarians than omnivores. 82 The EPIC-Oxford cohort study (44 561 participants) showed a 32% risk reduction of CHD in vegetarians than non-vegetarians. 83 However, subsequent studies suggest that the protective effect against CHD of vegetarian diets seems to be almost exclusively limited to the Seventh-day Adventists, who don’t smoke, don’t drink alcohol, do regular physical activity, and are very religious and socially connected. 84 Indeed, data from epidemiological studies of English and German vegetarians show only a modest protective effect against cardiovascular and overall mortality. 85–87 A German prospective study of 1225 vegetarians and 679 health-conscious non-vegetarians has shown that there is no difference in mortality among vegetarians and this control group of health-conscious individuals consuming meat three to four times per month. 88 Cigarette smoking, obesity, alcohol intake, and exercise patterns seem to explain most of the differences in cardiovascular mortality among these different groups. Another potential problem is diet quality, which can vary greatly among both vegetarian and non-vegetarians. 4 , 5 , 89

The effects of vegetarian diets on major cardiometabolic risk factors (i.e. hypercholesterolaemia, dyslipidaemia, hypertension, T2DM, and obesity) are more consistent. Well-educated vegetarians who consume balanced diets tend to have a lower body weight than non-vegetarians 21 together with lower levels of cholesterol, glucose, and blood pressure. 90 A recent umbrella review integrated evidence from 20 meta-analyses and found that people following vegetarian diets had significantly lower total cholesterol and LDL cholesterol than people consuming Western diets. 91 On average, total and HDL cholesterol are ∼0.36 and 0.10 mmol/L, respectively, lower in vegetarians than in omnivores. 92

A meta-analysis of 7 epidemiological studies (124 706 participants) found an 18% lower cancer incidence in vegetarians than omnivores {relative risk [RR]: 0.82 [95% confidence interval (CI): 0.67, 0.97]}. 82 Results from the EPIC-Oxford study on a cohort of 65 000 men and women found that the overall cancer risk was 10% lower in vegetarians and 18% lower in vegans than in meat-eaters. 93 However, after correcting for multiple confounding factors, only stomach and haematological cancers were significantly lower, while cervical cancer was 90% higher in vegetarians. Recent data from the UK Biobank prospective study on 409 110 participants show that compared with omnivores, vegetarians had a 13% and pescatarians a 7% lower overall cancer risk, respectively. In this study, vegetarians had a lower risk of colorectal and prostate cancer, and pescatarians had a lower risk of melanoma. However, when these data were pooled with eight previously published studies in a meta-analysis, only the association with colorectal cancer persisted. 94 These findings suggest that other factors beyond vegetarian diets may explain these associations. The incidence of lung cancer, for example, is lower in vegetarians than in people consuming typical Western diets, but this seems due primarily to the reduced smoking habit of vegetarians. No difference has been reported for lung cancer risk for vegetarians in maximally adjusted models. 95–97 The incidence of colon cancer is reduced by 22% among Seventh-day Adventist vegetarians, but not in British vegetarians. In the latter group, for example, it seems that vegans have an even higher risk of colon cancer, while in pesco-vegetarians, there is a 33% reduction, even after correcting for body weight. 95 The quality of diet probably plays a major role. Indeed, unhealthy plant-based diets rich in refined and processed carbohydrates and unhealthy fats are associated with higher risk of colon cancer, but healthy plant-based diets enriched in whole grains, legumes, and vegetables are associated with lower incidence of colorectal cancer, especially KRAS-wildtype subtype. 6 The risk of developing breast cancer is no different between vegetarian and non-vegetarian women in most studies, and some epidemiological data in Adventist and British women suggest vegans, but not lacto-ovo vegetarians, may have an increased risk. 98 The same is true for prostate cancer, with the risk no different among lacto-ovo vegetarians and omnivores but 34% lower in the Adventists vegans. 99 A lower intake of dairy products may explain this association because milk consumption increases serum IGF-1 levels, a risk factor for prostate cancer, breast, and colon cancer. 100

Very little is known about the effects of vegetarian diets on cognitive function and dementia risk. A recent systematic review and meta-analysis suggests that vegetarian diets are not associated with any significant improvement in memory when compared with omnivorous diets, but heterogeneity among studies was very high. 101 Findings from a small prospective study (5710 participants with 121 incident cases) conducted in Taiwan suggest that vegetarians might have a lower risk of dementia than non-vegetarians. 102

Data from a meta-analysis of 7 clinical trials including 311 participants show that consuming a vegetarian diet is associated with a reduction of mean systolic [−4.8 mmHg (−6.6 to −3.1)] and diastolic [−2.2 mmHg (−3.5 to −1.0)] blood pressure compared with non-vegetarian diets. 103 A meta-analysis of 11 trials and 983 participants showed that strict plant-based (vegan) diets seem less effective than less restrictive diets and reduced systolic [−4.10 mmHg (−8.14 to −0.06)] and diastolic [−4.01 mmHg (−5.97 to −2.05)] blood pressure only in patients with a baseline systolic blood pressure (SBP) ≥130 mmHg. 104 A recent meta-analysis of randomized trials show that the lacto-ovo vegetarian diet is as effective as other healthy diets containing some animal products [Dietary Approaches to Stop Hypertension (DASH) and healthy Nordic diet] at reducing blood pressure. In contrast, vegan diets did not significantly reduce blood pressure unless caloric restrictions was also prescribed, 105 suggesting that complete elimination of animal food is not required for lowering blood pressure and might even increase haemorrhagic stroke risk, possibly due to very low intake of saturated fat. 93 Other factors such as calorie restriction and weight loss, 30 , 54 , 106 lower dietary sodium and high potassium and magnesium intake, 53 , 55 and regular endurance exercise training 56 are important factors beyond fibre-rich plant food consumption. Moreover, findings from a meta-analysis of 15 randomized trials show that reduced alcohol consumption dose-dependently lowers systolic and blood pressure in both in non-hypertensive and hypertensive individuals. 107

The results of a recent meta-analysis of nine randomized clinical trials provide evidence that vegetarian diets can significantly reduce fasting glucose (range 0.1–1.0 mmol/L) and glycosylated haemoglobin (HbA1c) (range 0.12%–0.45%) together with LDL cholesterol (range 0.04–0.2 mmol/L) and body weight (range 1.3–3.0 kg) in T2DM patients. 108 Interestingly, one randomized clinical trial comparing a low-fat vegan diet with the American Diabetes Association (ADA) diet demonstrated that both diets caused significant improvements in HbA1c, body weight, plasma lipid concentrations, and urinary albumin excretion in individuals with T2DM. 109 Forty-three percent of patients randomized to the vegan group and 26% of those allocated to the ADA group reduced the use of glucose-lowering drugs. Moreover, among medication-stable patients, the effects of the low-fat vegan diet on HbA1c, weight, waist circumference, and LDL cholesterol were significantly greater than in the control group. Similar improvements in HbA1c levels have been found in a population of Korean men and women affected by T2DM. 110 Thus, these trials suggest that low-fat vegan diets might be more effective than conventional diabetic diets in glycaemic control, but more studies with long-term follow-up are needed to confirm these findings. Table 1 summarizes the ongoing clinical trials with vegetarian diet interventions in people with T2DM.

Study characteristics of completed and ongoing clinical trials in people with type 2 diabetes mellitus

ADA, American Diabetes Association; CI, confidence interval; F & V, fruits and vegetables; HbA1c, haemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; LF, low-fat; LOV, lacto-ovo vegetarian diet; MD, mean differences; SBP, systolic blood pressure; DNSG, Diabetes and Nutrition Study Group; EASD, European Association for the Study of Diabetes; NA, not applicable; RR, relative risk; F, females; M, males; NI, no information; OR, odds ratio; RCT, randomized controlled trial; IQR, interquartile range; M, males; WFPB, whole foods plant-based.

Randomized clinical trials are usually considered gold standard studies for evaluating the cause–effect relationship of health interventions, although misleading conclusions can easily occur due to low adherence to the intervention or inadequate follow-up time. To the best of our knowledge, there are no randomized clinical trials that have tested the effects of vegetarian diets alone on CHD event rates. The Lifestyle Heart Trial was designed to investigate the effects of an intensive lifestyle programme comprising a 10% fat whole foods vegetarian diet together with aerobic exercise, stress management training, smoking cessation, and group psychosocial support in 48 patients with moderate to severe CHD. 119 Only 20 of the 28 patients randomized to the experimental group completed the 5-year follow-up and experienced a small but significant regression of coronary atherosclerosis (a 7.9% relative improvement) and a decrease in symptomatic and scintigraphic myocardial ischaemia. 119 , 120 In contrast, patients randomized to the usual care control group who completed the study ( n = 15) experienced a 27.7% relative worsening of the average percent diameter stenosis. However, this was a very small, under-powered study that does not allow to differentiate the effects of the vegetarian regimen from those induced by the very low-fat diet, regular aerobic exercise, smoking cessation, and stress reduction programme.

Many randomized clinical trials have tested the effects of different forms of vegetarian diets on cardiometabolic risk factors. Recent meta-analyses reported that vegetarian diets significantly improve several risk factors, including body weight (1.2–2.8 kg reduction), 121 SBP (3.3–7.6 mmHg reduction), 103 , 105 total cholesterol (0.32–0.76 mmol/L reduction), LDL cholesterol (0.32–0.59 mmol/L reduction), high-density lipoprotein (HDL) cholesterol (0.088–0.093 mmol/L reduction), 122 and HbA1c (0.15%–0.65% reduction). 123 A crossover randomized trial showed that a vegetarian diet was as effective as the Mediterranean diet in reducing body weight and fat mass, but the former resulted in significantly lower LDL cholesterol levels in middle-aged men and women. 22 However, many of these meta-analyses were focused on relatively healthy populations or did not stratify patients for gender and disease status. Evidence of the metabolic effects of plant-based diets in people with CVD is limited. Table 2 summarizes the ongoing clinical trials with vegetarian diet interventions in people with CVD.

Study characteristics of completed and ongoing clinical trials in people with cardiovascular diseases

CI, confidence interval; CHD, coronary heart disease; CR, calorie-restricted; F & V, fruits and vegetables; LDL-C, low-density lipoprotein cholesterol; LF, low-fat; LOV, lacto-ovo vegetarian diet; MD, mean differences; RCT, randomized controlled trial; SBP, systolic blood pressure; AHA, American Heart Association; HbA1c, haemoglobin A1c; IQR, interquartile range; NA, not applicable.

To our knowledge, only one randomized clinical trial to date has investigated the effects of a vegan diet on cancer outcomes, and preliminary data show a significant reduction in body weight and cholesterol at 8 weeks. 130   Table 3 summarizes the ongoing interventional clinical trials on the effects of vegetarian diets in people with cancer.

Study characteristics of clinical trials in people with cancer

LDL-C, low-density lipoprotein cholesterol; MD, mean differences; NA, not applicable; SBP, systolic blood pressure; WFPBD, whole-food plant-based diet; CR, calorie-restricted; MGUS, monoclonal gammopathy of undetermined significance; N-111, nutraceutical supplement, ingredients unspecified.

To the best of our knowledge, no randomized clinical trials to date have investigated the effects of vegetarian or vegan diets on cognitive impairment or dementia outcomes. Our search of ongoing randomized clinical trials identified only one study testing the effects of a low-fat vegan diet on dementia (NCT04606420).

Accumulating evidence indicate that some vegetarians, especially vegans who are consuming restrictive diets, are at greater risk of developing haemorrhagic stroke, bone fractures, and a range of vitamin and mineral deficiencies that are particularly dangerous for growing children and pregnant and breastfeeding women. 136 , 137 Vitamin B12, for example, is an essential vitamin produced by specific strains of soil bacteria that animals ingest when grazing grass. During digestion, large amounts of vitamin B12 are formed and incorporated in the animal’s meat, milk, and eggs. Fish and shellfish also contain considerable amount of vitamin B12; for instance, 100 g of clams contain up to 49 µg of vitamin B12. People following strict vegan diets must take a vitamin B12 supplement and/or consume foods supplemented with vitamin B12, including vitamin B12–fortified nutritional yeast, to avoid developing megaloblastic anaemia, a potentially irreversible form of neuropathy, and impaired bone formation. Vitamin B12 in spirulina or other algae is not bioavailable and may even inhibit vitamin B12 metabolism, 136 but vitamin B12 in duckweed is bioavailable. 138 Other potential deficiencies that vegetarians may develop are those from iron and zinc and occasionally riboflavin. 139 These deficiencies are especially important in vegan children, pregnant/breastfeeding women, and those with menorrhagia. Many plant foods contain iron and zinc, but their bioavailability is limited due plant anti-nutrients, such as phytates, tannins, lectins, and oxalates. Cooking, sprouting, fermenting, and processing plant foods with vitamin C rich foods can increase iron and zinc absorption. 140 Dietary calcium deficiency especially when coupled with protein restriction and excessive sodium intake can increase the risk of bone fractures in ethical vegans who do not consume healthy diets rich in calcium- and protein-rich plant foods. 93 , 137 , 141–143 Many plants contain calcium, and in some of these, its bioavailability is very high. For instance, 40%–60% of the calcium contained in cabbage, broccoli, or broccoli sprouts is absorbed because of their low oxalate content, against only 31%–32% of the calcium in cow’s milk. 144 Legumes, soy products (especially tofu made with calcium sulphate), and figs are also excellent sources of dietary calcium and protein. Regular exercise training, adequate sun exposure, and vitamin D supplementation are also important to promote bone health and prevent fractures 145 and may play a key role in the protection against certain autoimmune diseases and advanced (metastatic) cancers. 146 , 147

Vegetarians should pay close attention to the quality and composition of their diets. Data from epidemiological studies suggest that men and women consuming plant-based diets rich in healthier plant foods (fresh vegetables, legumes, minimally processed whole grains, fruits, nuts, monounsaturated-rich vegetable oils, tea, and coffee) have lower risks of CHD and overall mortality with regular fish intake providing additionally health benefits. 4 , 87 , 148–150 In contrast, people eating ‘unhealthy’ plant-based diets that emphasize refined grains, potatoes, high-sodium preserved vegetables, fried goods, sweets, juices, and sweetened beverages experienced higher risk of CHD and mortality. 4 , 5 Similar results have been found for T2DM. 5 Plant-based food products marketed as vegetarian and/or vegan can be rich in refined starch, added sugar, HFCS, salt, partially hydrogenated ( trans ) fat, and saturated fatty acids from tropical oils (e.g. one tablespoon of coconut oil contains 12 grams of saturated fat). Consumption of ultra-processed foods rich in sucrose and in HFCS, even if labelled as ‘vegetarian’ or ‘vegan’, promotes the development of insulin resistance, cardiometabolic syndrome, fatty liver disease, CVD, and cancer. 151 , 152 High salt intake not only increases the risk of developing hypertension, CHD, and stroke, 55 , 153 but it also triggers inflammation by increasing monocyte CCR2 expression. 154   Trans -fatty acids from partially hydrogenated oils have markedly adverse effects on serum lipids, systemic inflammation, endothelial function, and ultimately on the risk of developing T2DM and CVD. 155 However, naturally occurring trans -fatty acids found in milk and meat of ruminant animals have also similar adverse effects on LDL cholesterol, total cholesterol to HDL cholesterol ratio, and apolipoprotein B levels as do industrially produced trans -fatty acids. 156 Finally, people consuming unhealthy vegetarian diets rich in refined carbohydrates might also be at risk of protein malnutrition. Plant foods contain all the nine essential amino acids but in different proportions. Legumes, for instance, are high in lysine, but low in tryptophan and methionine. In contrast, whole grains are low in lysine but high in tryptophan and methionine. Therefore, it is essential to consume every day a mixture of whole grains, beans and nuts, and/or protein-rich plant foods (e.g. tofu and mankai, a cultivated strain of the Wolffia globosa aquatic plant) to provide adequate amounts of all the essential and non-essential amino acids.

Consuming vegetarian diets rich in minimally processed plant foods has been associated with a reduced risk of developing multiple chronic diseases including CVD, diabetes, hypertension, cancer, and dementia. Data from randomized clinic trials have confirmed a protective effect of vegetarian diets for the prevention of diabetes, hypercholesterolaemia, hypertension, and overweight, but to date, no data are available for acute coronary syndrome, heart failure, stroke, cognitive impairment, and dementia, and there are very limited data for cancer. However, since many individuals commonly and increasingly adopt vegetarian diets worldwide for ideological, cultural, environmental, and personal factors, it is of paramount importance to define which vegetarian dietary compositions provide better health outcomes and which components are detrimental to human health ( Graphical Abstract ).

New randomized trials are needed to understand whether the advantages of healthy plant-based diets represent an all-or-nothing phenomenon and if consuming less strict plant-based diets containing small quantities of animal products (e.g. pescatarian or traditional Mediterranean diets) has beneficial or detrimental effect on specific health outcomes, including the prevention of haemorrhagic stroke and bone fracture. Further, mechanistic studies are warranted to enhance our understanding about healthy plant-based food patterns and the biological mechanisms linking dietary factors and chronic diseases.

Recommendations for clinicians and allied health practitioners

For overweight men and women seeking weight loss and cardiometabolic improvement as means of primary and secondary prevention of T2DM, hypertension, and CVD, well-balanced and supplemented vegetarian diets rich in minimally processed plant foods may be an option, especially when coupled with calorie restriction and regular exercise training as recommended in the 2018 Physical Activity Guidelines Advisory Committee Scientific Report. 28 , 157 Regular fish intake can provide additional cardiovascular health benefits. 158 Additional trials are warranted to determine whether patients with CVD will ultimately benefit from consuming vegetarian and vegan diets and, if so, in what ways. As with any potential therapeutic strategy, the risks and benefits of vegetarian diets must be discussed with patients. There is evidence to suggest that some vegetarians, particularly those who follow restrictive diets such as vegans, may be at greater risk of haemorrhagic stroke and bone fractures if they do not carefully plan their diets and consume fortified plant-based foods or supplements. In addition, vegans and some vegetarians may be at risk of deficiencies in vitamins and minerals such as vitamin B12, riboflavin, iron, zinc, calcium, and omega-3 fatty acids. This can be particularly dangerous for pregnant and breastfeeding women and growing children, as these nutrients are crucial for foetal and child development. It is recommended that anyone considering a vegetarian or vegan diet consult with a registered dietitian or healthcare provider to ensure that their diet is nutritionally adequate. Consuming vegetarian diets rich in refined grains, potatoes, high-sodium preserved vegetables, fried goods, sweets, juices, and sweetened beverages can increase the risk of developing T2DM and CVD morbidity and mortality. Finally, in the case of vegetarian diets and cancer, the benefits and risks are not well defined. As a weight loss strategy, this may be an option for some cancer patients, but there are currently no data to suggest that vegetarian or vegan diets in the absence of weight loss and/or changes in physical activity patterns will have a positive impact on cancer outcomes, including either recurrence or the development of metastatic cancers.

Supplementary data are not available at European Heart Journal online.

Disclosure of Interest

All authors declare no conflict of interest for this contribution.

Most extracted data and study materials are available from previously published research. Additional data extracted from the corresponding author of included studies will be shared upon reasonable request.

L.F. is supported by grants from the Australian National Health and Medical Research Council’s Investigator Grant (APP1177797), Australian Youth and Health Foundation, and Philip Bushell Foundation. W.W. is supported by grants from the National Institutes of Health on the epidemiology of cancer.

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• hypertension
• ldl cholesterol lipoproteins
• mediterranean diet
• cardiovascular diseases
• diabetes mellitus
• diabetes mellitus, type 2
• blood pressure
• hemoglobin a, glycosylated
• vegetarianism
• science of nutrition
• vitamin b12
• cognitive impairment
• diet, vegan
• plant-based diet

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Pros and Cons of a Vegetarian Diet

Malia Frey is a weight loss expert, certified health coach, weight management specialist, personal trainer​, and fitness nutrition specialist. 

 Patrizia Savarese / Getty Images

Many people adopt a ve getarian diet in an effort to boost their health or reduce their risk for disease. Certainly, the benefits of a plant-based diet are well documented. But not all vegetarian diets are nutritious.

The type of foods you choose to include in your meal plan (and those that you choose to avoid) make a big difference in the benefits you gain. A vegetarian diet full of processed foods is less likely to provide health benefits than a diet full of nutritious fruits, vegetables, legumes and grains.

As you think about adopting this food plan, consider all of the pros and cons of a vegetarian diet to make sure it's the right eating plan for you.

Reduced disease risk

May boost longevity

Increased food variety

Improved weight control

Offers complete nutrition

Reduced food costs

Friendly environmental impact

Ethical treatment of animals

Possible nutrient deficiencies

Fewer food choices

Reduced satiety

Less convenient

Not always healthy

Exposure to chemicals

There are many different types of vegetarian diets . The most common is the lacto-ovo vegetarian, or someone who avoids meat, poultry, and seafood but consumes dairy and eggs. Ovo-vegetarians eat eggs but avoid dairy, meat, and seafood. Lacto-vegetarians consume dairy but avoid eggs, meat, and seafood. These can all provide a variety of benefits.

Reduced Disease Risk

On a healthy vegetarian diet, you are encouraged to consume whole grains, legumes, fruits, vegetables, nuts, and seeds—foods that are lacking in the diets of many people who follow a more traditional food plan. These plant-based foods provide your body with important vitamins and minerals that boost your health and reduce your risk of many chronic diseases.

For example, in a large cohort study evaluating both vegetarian and vegan diets, researchers found that both groups experienced a reduced risk of cardiovascular diseases , cardiometabolic risk factors, and some cancers.

There is also some evidence that a vegetarian diet may help you to avoid conditions such as gallstones and kidney stones. A 2019 study published in the journal Nutrients followed over 4800 participants and concluded that by lowering cholesterol levels , a vegetarian diet successfully reduced the incidence of gallstone disease.

And a 2014 study investigating the effects of various diets on kidney stone formation determined that a balanced lacto-ovo-vegetarian diet can be protective against the condition as long as there is adequate calcium intake .

May Boost Longevity

There have been a number of studies investigating the link between vegetarian or vegan diets and longevity. Some studies have found that those who follow healthy plant-based diets live longer than those who eat meat.

A large cohort study published in 2014 found that vegetarians were 12% less likely to die from all causes combined compared to nonvegetarians.

However, results from studies like these can be tricky to interpret. The 2014 cohort study included 73,000 people but they were all Seventh-day Adventists who typically consume no alcohol and do not smoke.   These factors may have played a role in their longevity patterns.

Other studies have investigated the link between plant-based diets and longevity, with many finding a positive association. But it can be hard to tell if it is the diet itself or related factors that boost longevity.

For example, those who choose a vegetarian or vegan diet often practice mindful eating, exercise regularly, and manage stress with meditation or yoga . These habits may also play a role in providing the benefit.

Increased Food Variety

The standard American diet is called an omnivore diet because no foods are excluded. But often, people who consume an omnivore diet get into the habit of eating the same foods day after day. The result is that they eat a relatively limited number of foods or types of food.

For example, a traditional American dinner generally includes meat (such as a steak or pork chop), a starchy side dish (such as a potato or rice), and maybe a vegetable. Dairy products are often used as ingredients, side dishes, or toppings.

On a vegetarian diet, however, many traditional foods are not compliant. Therefore, when you begin this diet, you may have to get creative and experiment with foods that are not familiar. For example, in the absence of meat, lentils , beans , or peas might become the foundation of your meal. Then to fill out your plate, you can rely on a variety of vegetables .

Of course, just choosing to go vegetarian does not guarantee this benefit. A vegetarian can also get into a food rut and eat the same (unhealthy) foods every day. But switching to a vegetarian diet may provide the motivation to experiment with new healthier food options.

Improved Weight Control

Plant-based eating is often associated with losing weight . Studies have shown that those following a vegetarian diet typically consume fewer calories than an omnivore diet. Researchers have also found that the most restrictive variation—the vegan diet—is also likely to have the lowest caloric intake.  

A broad evidence review published in 2017 found that plant-based diets are an effective tool in the management and prevention of overweight and obesity.  

If you are trying to reach or maintain a healthy weight , the lower daily calorie intake associated with vegetarian or vegan eating may help you achieve your goal.

Offers Complete Nutrition

Getting the recommended intake of both macro and micronutrients is easier on a vegetarian diet than it is on the more restrictive vegan diet. And while there are still some concerns about nutritional deficiencies on a vegetarian diet, there are substantial resources available to help you met your nutritional needs.

For example, the USDA and the U.S. Department of Health and Human Services included a Healthy Vegetarian Eating Pattern as part of their 2020–2025 Dietary Guidelines for Americans. The guide provided recommendations for the intake of various food groups such as green leafy vegetables , starchy vegetables, legumes and beans , soy products , and others.

Recommended amounts are provided for daily caloric intakes ranging from 1,000 to 3,200 calories per day. By following this guide, you are likely to get the daily vitamins, minerals, and macronutrients needed for a healthy body. However, like any diet, you may fall short of nutrients if you don't take steps to eat a balanced diet .

Reduced Food Costs

Choosing a vegetarian diet may help you to reduce your food costs. But your total food costs will ultimately depend on the foods you choose to include in your meal plan.

Meat and seafood are typically expensive and for many are a major component of their total grocery bill. Convenience foods and fast foods that are not compliant on a vegetarian diet can also be pricey. When you remove these foods from your diet, you eliminate the substantial food costs that are associated with them.

Bulk grains and legumes are usually budget-friendly. And if you buy produce in season , you can cut costs as well. Off course, vegetarian-convenience foods and meat alternatives can be expensive, but they are likely to cost less overall than a diet rich in animal-based products.

Friendly Environmental Impact

There is increased concern in the environmental community about the impact of livestock and livestock farming practices on the earth. So, some people choose to eliminate meat and eat a vegetarian diet because they feel it is better for the planet.

The farming of plants to produce fruits, vegetables, nuts, seeds, and grains requires fewer land and water resources than the production of meat, poultry, and dairy. And cows produce more greenhouses gasses than plants, which leads some to believe that eliminating meat and dairy from the diet helps to reduce the risk of global warming.

Several research studies have even suggested that the vegan variation of a vegetarian diet is better for the planet than other diets, including the popular Mediterranean diet .  

Ethical Treatment of Animals

Because no animals are killed to produce vegetarian foods, many choose this diet because of concerns about animal cruelty. However, those who choose to consume eggs and dairy may still have to confront issues regarding the treatment of chickens and cows.

Animal rights activists prefer that consumers choose a vegan diet to promote the ethical treatment of animals. But the less-restrictive vegetarian option still reduces the overall impact on the animal population.

Even though a vegetarian diet offers some substantial benefits, there may be drawbacks as well.

Possible Nutritional Deficiencies

A well-rounded vegetarian diet can provide adequate nutrition. However, there are certain key nutrients that are generally found in animal foods that may be lacking in a vegetarian diet if the diet doesn't include a variety of healthy foods.

• Zinc : Studies have shown even though zinc intake tends to be lower in vegetarians, their bodies adapt to lower levels through increased absorption and retention of the mineral. Researchers also note that a well-planned diet can provide adequate zinc through plant-sources such as whole grains, tofu, tempeh, legumes, nuts and seeds, fortified breakfast cereals, and dairy products.
• Vitamin B-12 : Vitamin B-12 , or cobalamin, is found in beef, liver, fish, shellfish, chicken and other meat-sources—foods not consumed on a vegetarian diet. But eggs contain vitamin B12, as well as some fortified breakfast cereals and dairy products. Researchers have found, however, that supplementation may be needed for people who follow a vegetarian or vegan diet.
• Vitamin D : Some researchers and health experts have raised concerns about vitamin D levels in vegans and vegetarians. The vitamin is found naturally in fish, fish liver oils, and egg yolks, and it is available in fish oil supplements , but most of our vitamin D comes from exposure to sunlight. Two excellent vegetarian sources of vitamin D include maitake mushrooms and Portobello mushrooms. Fortified nut milk and fortified grain products may help increase your vitamin D intake during the winter months, as may multivitamins and supplements .
• Calcium : Vegetarians who do not consume dairy may need to plan meals carefully to get enough calcium . But green leafy vegetables, white beans, pulses, sesame seeds, and some dried fruits are rich in the nutrient. Many nut milks and brands of orange juice are also fortified with calcium.
• Omega-3s : Lastly, a vegetarian diet can be deficient in omega-3 fatty acids . But soy, pumpkin, flax, or chia seeds and walnuts are good sources of omega-3.

It is important to read nutrition labels and choose foods that contain key vitamins and minerals to avoid nutritional deficiencies.

Fewer Food Choices

If you are used to consuming a traditional diet that includes meat, seafood, and other animal products, you may find the vegetarian diet to be limiting at first. Certainly, it takes time to adjust to the eating style if you are used to building meals around bacon at breakfast, deli meats at lunch, and beef or chicken at dinner.

But there are a wide variety of resources to help you learn to find or create satisfying meals without meat . Most vegetarians find that there are plenty of options not only in grocery stores and at restaurants, but even when dining with friends and family in private homes. Plant-based dishes are often encouraged by health experts for meat-eaters, so it is not uncommon to see hearty dishes that are vegetarian-friendly.

Reduced Satiety

Studies have found that vegetarian diets tend to be lower in calories, fat, and protein than omnivore diets. Foods that are higher in fat and protein help you to feel full and satisfied after eating.

Some carbohydrate-rich foods such as fruit or refined grains are digested more quickly and may leave you feeling hungry soon after a meal or snack. As a result, when you switch to a vegetarian diet, you may feel less satisfied and hungry more often.

But careful food choices can help boost satiety. Hearty beans and whole grains are high in fiber and help you to feel full. Snacks that include nuts or seeds also provide protein and fat to increase feelings of satisfaction after eating.

Less Convenient

Even though plant-based foods are getting easier to find, those who follow a strict vegetarian diet will still need to read ingredient lists, especially if they choose to consume processed foods. Foods that you might assume to be free from animal by-products may contain gelatin , whey, casein, or other foods that are non-compliant.

Dining out can also be a challenge, especially when you are first adapting to a strict vegetarian diet. While some restaurants provide meat-free meals, the meal may be made with dairy or other animal products. Vegetable soup, for example, might be made with chicken or beef broth , or even vegetable broth that used an animal bone for flavoring.

Eventually, you are likely to find restaurants with plenty of plant-based compliant meal choices. When dining at someone's home, bring a vegetarian recipe that you can enjoy and share with others.

Not Always Healthy

While consuming a vegetarian diet can provide health benefits and help you maintain a healthier weight, it is not a guarantee. There is an increasing number of heavily processed vegetarian foods. Many times, these foods contain more fat, sodium , added sugar , and calories than their traditional counterparts.

Relying on these convenience foods leads to the same limited food palate and health concerns associated with the traditional American diet.

In fact, one study that investigated vegan diets found that those who followed a diet that included whole grains, fruits, vegetables, nuts, legumes, oils, tea, and coffee had a substantially lower risk for heart disease. But those who chose a less healthy version of the diet, including sweetened beverages , refined grains, potatoes, fries, and sweets had a higher risk.

Exposure to Chemicals

There has been some concern in the health community about the increased risk of exposure to herbicides and pesticides among those who consume a plant-based diet.

In fact, some studies have shown that because fruit, vegetables, and grains are often farmed using these chemicals, vegetarians may be more exposed to pesticide residues than the general population due to specific dietary habits. However, even though exposure to pesticides may be higher, other researchers have found that it is still likely to fall within safe guidelines.

Additionally, it is not clear if the limited exposure has more potential for harm than exposure to hormones or antibiotics sometimes found in animal foods or if the potential exposure reduces the benefits gained by consuming a plant-based diet.

A simple solution to this concern is to buy organic foods. However, these products are often expensive and may not be available in all areas. If organic products are not an option for you, health experts advise that you wash fruits and vegetables carefully to limit exposure.

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Chang CM, Chiu T, Chang CC, Lin MN, Lin CL. Plant-based diet, cholesterol, and risk of gallstone disease: a prospective study . Nutrients . 2019;11(2):335. doi:10.2290/nu11020335

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By Malia Frey, M.A., ACE-CHC, CPT  Malia Frey is a weight loss expert, certified health coach, weight management specialist, personal trainer​, and fitness nutrition specialist. 

Essay On Vegetarian Diet

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IELTS Blog & IELTS Mock Test

Ielts exam preparation for a higher band score., ielts essay: everyone should adopt a vegetarian diet.

You should spend about 40 minutes on this task.

Write about the following topic:

Everyone should adopt a vegetarian diet because eating meat can cause serious health problems.

Do you agree or disagree?

Give reasons for your answer and include any relevant examples from your own experience or knowledge.

Write at least 250 words.

Model Answer 1:

People should consume more vegetables and fruits and as little meat as possible because intake high amount of meat can cause serious health issues. In my opinion, the consumption of a vegetarian diet is a better way to live a healthy life and I agree with the notion.

Firstly, vegetarian diets are cheaper and more healthy. If the majority of people become vegetarians, a nation needs to struggle less to become self-sufficient on food production. Moreover, such diets are easily accessible both for the poor and rich citizens. Most importantly, plant-based food provides necessary vitamins and food values, especially fibre, which protect us from many dangerous diseases. Not to mention, producing vegetarian food is more ecologically sustainable, and it reduces damage to the environment.

On the contrary, a certain portion of meat is necessary for a balanced diet because it contains protein, calcium and other vitamins. Nevertheless, these can be also gained from alternative sources like beans, mushrooms and nuts. Most meats are cholesterol-rich, which is detrimental to the human body and cause diseases. On top of that, deadly illnesses like cardiovascular diseases, obesity and brain haemorrhage are increasing gradually all around the world due to a high intake of red meat in different countries and I believe a vegetarian diet is a perfect solution to all these problems.

In conclusion, a healthy diet determines our wellbeing and life expectancy. Since a vegetarian diet is far beneficial than meats, we should choose wisely and decrease our meat intake as little as possible.

[By – Amraiz Ali Shahzad ]

Model Answer 2:

When it is perfectly possible to lead a healthy life by eating plant-based food, I see no justification for killing birds or animals for our food. Therefore, I completely agree with the argument that everyone should adopt a vegetarian diet.

There are several benefits to following a vegetarian diet. To start with, plant-based food is rich in vitamins, minerals, anti-oxidants and other nutrients required for good health. What’s more, most fruits and vegetables contain little or no cholesterol or calories. Research has shown that vegetarians are less likely to develop health-related problems like obesity, cancer or heart diseases. Health benefits are not the only reason to follow a vegetarian diet. When we obtain our food from plants, we can also stop cruelty to animals.

By contrast, non-vegetarian foods such as fish and meat are high in cholesterol, fat and calories. Regular consumption of red meat is known to increase a person’s risk of cancer and heart disease. In addition, unlike fruits or vegetables, fish and meat cannot be eaten raw. The slaughtered animal may have some illness. If half-cooked meat is eaten, it can cause deadly infections in human beings. In fact, many cases of food poisoning are caused by the consumption of contaminated meat.

The quality of non-vegetarian food has also deteriorated over the years. Seafood has become contaminated due to the pollution in ocean water. It is a well-known fact that farm animals are given steroids to grow rapidly. When we eat their meat, the steroid also enters into our body. This leads to several problems like precocious puberty in children.

To conclude, vegetarian diets are healthy and do not constitute cruelty to animals. Therefore, I believe that everyone should adopt vegetarianism.

[Written by – Manoj ]

3 thoughts on “ IELTS Essay: Everyone should adopt a vegetarian diet ”

Excellent examples to prove to be vegetarian in IELTS essay. I need help in IELTS reading & listening in table chart completion.

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The Importance Of The Vegetarian Diet

Q1/ Why has the vegetarian diet become popular in Australia? The number of people who are vegetarians in Australia has raised from 1.7 million people to 2.1 million people from 2012 to 2016 (Roy Morgan Research,2016). The question will investigate the causes of why Australians have shifted to a vegetarian diet and why vegetarian diet is becoming popular in Australia. The answer of this question can be obtained from the health, environmental and ethical reasons that affect the reasons behind why some Australians have shifted to a vegetarian diet. Firstly, many Australians have shifted to a vegetarian diet, one of the main reasons behind it is due to health reasons. This means that people who are vegetarian think that the vegetarian diet is healthy and suitable for all stages of the life cycle (Healey,2012). According to Healey (2012) that eating meat can be hazardous to people’s health because animal products and meat have a higher level of cholesterol which can lead to build up a plaque in arteries which causes heart disease and heart attack. Similarly, Merkes (2012) argues that eating meat is linked among rising of death from cancer and heart disease, Healey (2015) says “it’s not just the saturated fat and cholesterol” (P.27), humans are not created to eat meat because of its nature and the new agricultural methods. The animals which are in farming industries are given antibiotics and drugs to grow faster, therefore their products can have side effects on human’s health

Meat Dairy, And Eggs, Oh Why By Rebecca Dent

“Meats, Dairies, and Eggs, Oh Why” (2014) is an argumentative essay written by Rebecca Dent that explains the benefits of eating a plant-based diet and advocates for the better treatment of the animals affected by the meat industry. Dent supports her assertions by discussing the negative health effects of an omnivorous diet, addressing reasons some might be hesitant to convert to a plant-based diet, describing the advantages of substituting meat for vegetables for both the consumers and the animals, and finally, by including expert opinions and statistical facts. Dent’s purpose for this essay is to highlight the benefits of vegetarianism in order to convince readers to convert to a plant-based diet. The intended audience for this argument is those who currently eat an omnivorous diet so that they would assess and change their eating habits.

The Controversy Of Vegetarianism In Australia

One of the biggest ethical issues in food today is centred around eating or not eating meat. There are many people for eating meat and many against it and is often a hotly debated topic. The number of vegetarians in Australia is rising steadily each year with approximately 2.1 million or 11.2% of the Australian population are practising vegetarianism.

The Environmental Sustainability Of Meat Production

For years vegetarian and vegan diets have been gaining popularity. This rise in popularity is due largely to the belief that a vegetarian diet has numerous health benefits and the animals being raised to be slaughtered are not being treated humanely. These are both good reasons for adopting a meat-free lifestyle, but there is an even more pressing reason. The current rate of meat consumptions, especially in developed nations, is consuming natural resources at a rate that is not sustainable. The amount of resources such as land, water, and crops consumed to support meat production is staggering. In addition to the resource consumption, meat production is also contributing to critical global environmental issues such as deforestation and ozone depletion.

Arguments Against Veganism

Many people argue that the reason the meat consumption is still so prevalent is due to the culture that we were raised on. One way to counter this is to bring up how there has been cultural shifts in today’s society. This is especially relevant the younger generations because many younger people are deviating from the traditional norm. It is somewhat counteractive to claim to not follow traditions and yet still uses tradition and culture as justification for the consumption of animal products. In terms of the fact that it is in human nature, this may be true but civilization has progressed enough that we don't need to do a lot of things which we typically had to do out of survival. There are still societies which do need meat to survive but these would mostly be developing countries. In developed countries where there is a surplus of food and is actually a whole culture centered around using food as a medium of art, cuisine, we no longer need meat to survive. In fact, there are many populations where they do not eat meat and they are just as health if not healthier than those who do. There is the idea that vegans as a whole are too aggressive

Should we all become vegetarians? Essay

As we can now observe, vegetarianism has become something fashionable, and the number of people who reject eating meat is constantly increasing. In Britain, for instance, over 5 million people have done it so far. It is obviously connected with the recent animal diseases, but this tendency is likely to spread on the other regions of the world. However, it is not only a fashion or fear of illnesses. I myself became a vegetarian about 2 years ago, and I can see a number of reasons why people should stop eating meat. They are mainly of ethic, economic and health type. Those who think in an ecological way should also be aware of how this meat consumption ruins our environment. I don’t have an intention

Vegetarianism for Dummies Essay

They say, “You are what you eat” and if making good food choices makes you a healthier and happier person, why are healthy food trends seemingly misunderstood and becoming a thing of the past? This semester I will be researching the advantages of choosing to obtain a vegetarian lifestyle and why some individuals are making arguments that are extremely against the practice. This topic is appropriate for a semester of sustained research because there are multiple viewpoints on the issue (including people who have experienced positive health benefits when they cut meat out of their diets, people who disapprove of the industry’s animal treatment, and people who strongly feel that there are extreme health risks and financial burdens that come

A Vegetarian Lifestyle

Imagine blood dripping off the walls, streaming into huge drains, and innocent animals being slashed open. Their screams echo throughout the halls of the slaughterhouse, but their screams are not alone. They are not alone because even the bloody granite records the past. Guess where this all happens? Not a horror movie, not in Japan. No, this happens in a slaughterhouse located in the United States. Now pick up that hamburger, and take a good look. One may see those poor souls of innocent animals flash before one’s eyes. If one looks, then one can see the unjust treatment these poor animals have to go through to just die. An individual might rethink meat in general if a slaughterhouse had see-through walls. A vegetarian lifestyle is not only beneficial because it can save animals, but it also saves people. A vegetarian lifestyle includes a more beneficial diet than one that consumes meat. For many reasons it is best to be vegetarian because it saves people from health problems, and because if the country keeps using all of these nonrenewable resources, what will people have in the end? The answer is nothing.

The Key to a Healthy Vegetarian Diet

Hindus have been doing it for thousands of years; then why is maintaining a vegetarian diet so difficult in the 21st century? The key to a healthy vegetarian diet is knowing what to eat and what not to eat, rather than simply avoiding meat. As Hobson (2009) points out, "remember, the root of vegetarian is 'veg,' not 'junk.'" The 21st century model of vegetarianism does not always involve the daily simplicity of whole grains, pulses, and nutrient-packed vegetables. Some vegetarians reach for pre-packaged, processed foods conveniently located on the shelves of Whole Foods. Another problem with the 21st century model of vegetarianism is faddish trends, such as the all-raw vegan diet. One former raw vegan, profiled by Mann (2008), had her kids on a raw vegan diet too, and they developed malnutrition. The children also started gorging on dairy products and eggs, signs that their bodies were lacking in vital nutrients (Mann, 2008). Although she still incorporates raw food into her mainly vegetarian diet, the mother has realized the importance of moderation. Therefore, a vegetarian diet can be tremendously healthy and ethically sound, as long as sound nutritional principles are followed.

Meat : The Real Cost

Eating an animal and plant based diet does not guarantee health. Too many animal based products and one can be on the way to obesity. All foods no matter what kind should be eaten in moderation. There are certain omnivores that believe that vegetarians are inferior due to what they suppose to be a lack of nutrients (“Red Meat”). Many meats consumed even with little amounts can eventually lead to high blood pressure, diabetes and heart disease. With a plant based diet, the risk of developing these diseases is less likely because the major cause of them is eliminated from the body (Mann, Jim, and Jim I Mann). The reason why the risk of developing heart disease is smaller is because vegetarians focus primarily on foods high in fiber and low in fats, which in turn is less fat the consumer has. In a study of half a million people, within a span of 10 years, meat eaters were more likely to develop serious diseases or cancer than non meat eaters (Lea, E. J). Omnivores are not inferior in health to vegetarians. However, vegetarians are also not inferior in health to omnivores.

The Benefits Of Vegetarianism

Vegetarianism is a controversial topic that involves the consumption of meat. Should one become a vegetarian? If consuming meat involves the production of factory farming and health risks the consuming meat is not good. If consuming meat is not good, one should become a vegetarian. Therefore one should become a vegetarian. A suitable beginning would be to define a factory farm.

The Pros And Cons Of The Vegetarian Diet

Few factors are as important to human health than one’s diet. A poor diet can have devastating effects to one’s health and well-being. For this reason, there are some key components the U.S. Department of Health and Human Services, along with the Department of Agriculture, suggest be part of one's eating pattern. These key components include a variety of vegetables, fruits, grains, fat-free or low-fat dairy or soy, a variety of protein foods, and oils. They also suggest limiting intakes of saturated fats, trans fats, added sugars, and sodium. Overall, the 2015-2020 Dietary Guidelines suggest that it is not necessarily about each and every individual food or beverage item that is consumed, but how that plays into an entire “eating pattern” and how everyone can make small shifts within their eating pattern to maintain a healthier life and decrease chances of developing a chronic disease. With all of these factors in mind, a diet that claims to be healthier, better for the environment, and help lower chances of disease is the vegetarian diet. There are many arguments for and against vegetarianism however, some of which are contrasting views of the same point. benefits. Because diet is such a key component of human health and wellness, for anyone considering the vegetarian diet, it is important to analyze these contrasting arguments.

The Pros And Cons Of Vegetarianism

Did we bring up the awareness that factory farms generate billions of pounds of dung from meat, all of which arrives at lakes, rivers, and your drinking water? The drugs and bacteria that end up in canals are the number one source of water pollution (“Vegetarianism and”). The only foul-proof solution to not polluting the water is not eating meat at all. Vegetarianism is a path of lifestyle where people chose not to eat meat. There are many reasons why people would decide that route, but 69% of the current vegetarians chose to not eat meat because of their health (“Reason for”); that is the majority! Although meat-eaters get more protein from meat, it is encouraged to switch to vegetarianism because it will protect the rights of many animals, it will help the environment, and it will help people pursue healthy lives.

The Benefits Of Becoming A Vegetarian

The consumption of meat has always been the most common form of receiving the needed nutrition, of an average body, in order to acquire and maintain a healthy lifestyle. Although packed with an abundance of proteins, iron, and amino-acids, meat has recently received a negative reputation of becoming detrimental to your health; titled a leading source of heart disease, obesity, cancer, diabetes, and even impotence. In result, countless individuals have sought a solution reserving to methods such as vegetarianism to obtain such needed nutrient with little to no health risks. Similar to meat eaters, vegetarians seek an equal nutritional diet without the consumption of any meat or animal products with the belief of avoiding health diseases prevalent in meat eaters. Becoming a vegetarian does not necessarily mean an individual follows a healthier diet, but then again, neither does being a meat-eater; so what benefits are linked with each diet, is there a difference in cost, and how is one distinguishable from the other in the long run?

Vegetarianism: The Advantages And Disadvantages Of Non-Vegetarians

Individuals sometimes label themselves "vegetarian" while practicing a semi-vegetarian diet or flexitarian diet which is the one that is plant-based with the occasional inclusion of meat products such as fish and poultry (white meat). These diets may be followed by those who reduce animal flesh consumed as a way of transitioning to a complete vegetarian diet or for health, ethical, environmental, or other reasons.

“Every time we sit at a table to enjoy the fruits and grain and vegetables from our good earth, remember that they come from the work of men and women and children who have been exploited for generations.” These words of Cesar Chavez, co-founder of the United Farm Workers, perfectly describe the injustice farm workers face in producing our food and including humans when talking about cruelty free. Conversations surrounding notions of vegetarianism as inherently cruelty free seldom incorporate the advocacy of more rights for farm workers. As a conflicted meat eater, I can concede that the fight for vegetarianism is honorable and consuming fewer animal products would be beneficial for our society, however, promoting meat-free meals and products as “cruelty free” mistakenly limits the cruelty of the food production system to animals. Comparatively, our food production system also exploits factory farm workers, a point also overlooked in conversations regarding ethical eating. Ultimately, the fundamental problem with vegetarianism is the cruelty free platform, that too often ignores the inhumane working conditions of farm workers. That being so, not eating meat does not place you above everyone else on the moral scale or mean you practice cruelty free when exploited laborers in our food production system, most of whom are undocumented, do not have their liberation.

Related Topics

• Vegetarianism
• Ethics of eating meat

Can Vegetarian Diets Be Healthy? Essay

Introduction.

Vegetarianism, with its pluses and minuses, is the most widespread alternative to the traditional food system. Millions of people in the world consider themselves vegetarians and make a choice in favor of products of vegetable origin, as well as certain components of the animal kingdom such as eggs, milk, etc. In this regard, one should not confuse vegetarianism with veganism; the first concept implies the rejection of meat and most animal organisms, while vegans do not eat absolutely any animal products and prefer exclusively plant foods.

Vegetarianism is widespread, and it is required to not only consider its features but also to determine whether such a diet has benefits and disadvantages. The analysis of the effectiveness of such a nutritional principle for the body can confirm, or, on the contrary, refute the theory about the advantages of vegetarianism and its beneficial effect on body functions.

Peculiarities of Vegetarian Diets

Almost all diets that are based on the principles of vegetarianism have similar rules of nutrition. Thus, for example, different products of animal origin are replaced by vegetable ones in the form of legumes, cabbage, nuts, etc. The liquid is used in sufficient quantity since the danger of dehydration can emerge; in this case, at least two liters of water should be consumed daily (Nordqvist, 2017).

Any sweet foods are usually excluded from the diet as they contain various impurities and oils, which are considered unacceptable in vegetarianism. As Wells (2015) remarks, the replacement of flour confectionery products is usually made up of dried fruits. On the whole, according to Wells (2015), virtually any vegetarian diet provides meals in the standard model, that is, four to five times a day, and does not imply any starvation as some people suppose.

Reasons for Refusing Meat

The roots of the so-called ideological vegetarianism, which implies the refusal to consume meat for moral reasons, lie in the matters of ecology or animal protection. The idea of ​​stopping eating meat is also often received by people who have some health problems and are forced to abandon animal protein for practical reasons. Also, a vegetarian diet is typical for a number of Eastern religions, including world beliefs, and all their new adherents, even those living on the other side of the world, prefer to consume such food.

Based on a variety of reasons, it is necessary to consider the merits and demerits of such a principle of nutrition in detail and pay attention to some significant facts that are scientifically confirmed. Certain arguments can be cited in favor of vegetarianism and against it. Thus, it is essential to pay attention to all possible and evident pluses and minuses. According to the analysis, competent conclusions can be made about the benefits or harm of such diets.

Advantages of Vegetarian Diets

Today, vegetarian diets are very popular all over the world and are preferred by people from different countries. Many adherents of vegetarianism claim that this food system is the source of health and youth and helps to prevent and treat many diseases. Some organizations, fighting for animal rights, advocate the refusal to eat meat, fish, and poultry. If it is about the health benefits, it is possible to highlight several essential benefits that the use of products of vegetable origin gives.

Reducing the Risk of Cardiovascular Diseases

The set of products of any vegetarian diet contains a very small amount of fats with a high content of saturated fatty acids. As a result, such a type of nutrition minimizes the risk of gaining excess weight (Nordqvist, 2017). It, in its turn, minimizes the possibility of developing diseases associated with the cardiovascular system because excess fat mass often leads to heart problems, increased blood pressure, and other related factors. Nordqvist (2017) also notes that, based on the studies conducted in 2016, people who often consume red meat have a slightly higher risk of death from excess calories than those who completely abandoned such a product. Accordingly, vegetarianism has a beneficial effect on the general tone of the body and the cardiovascular system.

Prevention of Heart Attacks and Strokes

Vegetarian food normalizes the level of cholesterol, strengthens the immune system, and also supplies the body with a very important fiber. Earlier, it was supposed that the reduction of animal fats in the diet was insignificant but still led to a drop in the level of cholesterol. However, the situation is more optimistic than it seemed, and the more radical the rejection of meat and meat products is, the more benefits for heart and brain vessels it brings. According to Wells (2015), this type of nutrition contributes to normalizing the level of cholesterol in the blood, which has a positive effect on the prevention of heart attacks and strokes. Therefore, this advantage is undoubtedly very significant.

High Content of Antioxidants for Recovery from Injuries and Diseases

Vegetables and fruits are known to provide the body with vitamins and minerals that are necessary for the normal operation of all systems. Beans and seeds are good sources of protein. Vegetables consist of phytochemical combinations that prevent some chronic diseases. Green vegetables are rich in antioxidants. Also, plant products are suppliers of natural sugars, various useful enzymes, and microelements.

As Coleman (n.d.) notes, many useful substances that are found in green vegetables are almost the best regenerating elements that stimulate the recovery of the body after severe injuries or illnesses. Moreover, as Lamuye (2018) remarks, the increased content of antioxidants in a diet is natural prevention against intoxication of the body, for example, through the polluted air or an increased level of radiation background. Therefore, such a type of nutrition deserves particular attention.

Reducing the Risk of Cancer Development

Any diet with high-fat content, namely meat, increases the secretion of bile in the intestine, which leads to the emergence of cancer tumors. It is also such food that causes the risk of breast, colon, ovarian, and prostate cancer. As Heid (2016) claims, vegetarians have a lower level of secondary bile acids than non-vegetarians. Differences in the microflora of vegetarians’ intestines and meat-eaters are also significant. The bacterial flora of vegetarians has a much lesser ability to convert bile into a potential carcinogen. In general, scientists agree that the possibility of forming a cancerous tumor depends on nutrition by 50-70% (Heid, 2016).

Fresh fruits and vegetables contain substances that protect the body from dangerous neoplasms. Moreover, the human digestive tract is poorly adapted to digesting meat because this food is too heavy and high-calorie. Accordingly, vegetables and fruits are not only useful but also compulsory products that should be present in the diet to prevent cancer in various forms of its manifestation and protect the body from other severe diseases.

Shortcomings of Vegetarian Diets

Despite the advantages mentioned above, vegetarian diets can sometimes harm the body. Essential shortcomings can be caused by different reasons; although different people individually perceive certain diets, some principles of vegetarian nutrition are rather controversial. Therefore, these disadvantages should be considered in more detail.

Lack of Useful Vitamins and Minerals

Despite the fact that a vegetarian diet provides the body with all the necessary nutrients, some of them can be obtained in larger quantities only from meat or fish. The vegetarian principle of nutrition does not fully meet the human needs for protein, calcium, vitamin B12, iron, and zinc. For instance, the shortage of B12, as Fetters (2014) notes, is fraught with fatigue, weakness, loss of appetite, and depression.

Vitamin B12 is abundant in soy, grain products, as well as in food of animal origin. Meat is considered the basic source of this useful element. Milk and dairy products are generally rich in vitamin D. Meat, chicken, fish, and poultry contain large amounts of iron and zinc. Milk, cheese, yogurt are valuable sources of calcium. Meat contains protein, and it is also the source of essential amino acids that the body needs. The phosphorus that meat contains is digested more easily than that found in legumes and cereals. All these nutrients are not contained in large quantities in a vegetarian diet; therefore, health problems can arise in case of the lack of them.

Contraindications to Pregnant and Lactating Women

During pregnancy, the need for nutrients and useful elements increases. According to Illmatical (2016), pregnant women should constantly monitor whether they receive enough protein. Different fatty acids and other useful elements are the basis of the baby’s nutrition both in the womb and during breastfeeding. Therefore, a vegetarian diet is extremely undesirable in such cases as it can harm children.

Meat and Other Animal Products Are Delicious

Perhaps, the factor of pleasant and rich taste is not a significant argument in favor of an anti-vegetarian diet. Nevertheless, many lovers of meat and fish dishes confirm that they feel a surge of energy when they feel the smell of their favorite product and then taste it. According to Morris (2013), a huge number of people around the world confirm the fact that the presence of meat in the ration makes eating not only more diverse but also tasty, and many supporters of meat diets cannot give up eating animal products. Also, in addition to taste, consistency plays a significant role; the body gets used to receiving food in the form of animal fiber and eventually adapts so much that people experience not only a psychological but also a physiological need for meat. Therefore, such a factor as taste should also be considered.

Thus, a proper analysis of the effectiveness of vegetarian diets can confirm that it has both specific advantages and disadvantages, and various arguments for and against such a diet can be cited. The principles of healthy eating do not necessarily have to provide for a complete rejection of a particular diet. It is essential for the body to receive a certain amount of nutrients, vitamins, and minerals. It especially applies to pregnant women, as well as those who need recovery from injuries and illnesses. Vegetarian diets have a number of advantages, but it is important to keep a balance in the diet in order for the body not to feel the necessity of certain substances.

Coleman, E. (n.d.). Advantages of vegetarianism . Web.

Fetters, K. A. (2014). 12 things you need to know before going vegan . Web.

Heid, M. (2016). You asked: Is a vegan diet better? TIME Health . Web.

Lamuye, A. (2018). 10 health benefits of a vegetarian diet, according to a nutritionist. Evening Standard . Web.

Morris, M. (2013). 9 reasons to reject vegetarianism . Web.

Nordqvist, C. (2017). What’s to know about eating vegan? Web.

Illmatical, C. (2016). Pros and cons of eating vegan during pregnancy . Web.

Wells, C. (2015). 5 reasons a vegetarian diet is good for you . Independent . Web.

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