introduction to nutrition research paper

Introduction to Research in Nutrition and Health

• Eunsook T. Koh 2 &
• Willis L. Owen 2  

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Research is simply a way of solving problems, and it is defined as planned studious and critical inquiry and examination aimed at the discovery and interpretation of new knowledge or expansion on a topic or idea. Quality assurance, surveys, new product evaluation, and case report are all examples of research. The purpose of these activities is to document “what works and what does not work,” which answers particular research questions. Useful research studies may be done to substantiate other previous investigations. Studies of diet and disease relationship and studies of various nutrition therapies are absolutely indispensable in substantiating the value of nutrition in the health care environment.

• Scientific Method
• Blood Cholesterol Level
• Manipulate Variable
• Health Care Environment
• Increase Bone Density

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Eunsook T. Koh & Willis L. Owen

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Koh, E.T., Owen, W.L. (2000). Introduction to Research in Nutrition and Health. In: Introduction to Nutrition and Health Research. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-1401-5_1

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An Introduction to Nutrition

(13 reviews)

Copyright Year: 2012

Publisher: Independent

Language: English

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Reviewed by Sheila Cook, Family and Consumer Sciences Instructor, Pittsburg State University on 1/16/23

For the intended audience, the text covers the necessary components of an introductory nutrition course. This text is a contender for an adopted online text for my nutrition and health course. It is easy to read and follow. read more

Comprehensiveness rating: 5 see less

For the intended audience, the text covers the necessary components of an introductory nutrition course. This text is a contender for an adopted online text for my nutrition and health course. It is easy to read and follow.

Content Accuracy rating: 5

The text is accurate concerning the basics of nutritional science and health. The author(s) present accurate relationships between nutrients, eating habits, good living, and overall health spanning the life cycle.

Relevance/Longevity rating: 4

Content is relatively accurate, but needs updating to stay current with trends, issues, and updated guidelines. The majority of the science content stays basic. Instructors can easily add supplemental materials if needed, especially in the areas of fad diets and trends, and new discoveries pertaining to research.

Clarity rating: 5

The text includes appropriate language and terminology necessary for an introductory nutrition and health course. The text contains appropriate content for students who are satisfying general education requirements.

Consistency rating: 5

The text is set up with an appropriate index. Content chapters flow easily from one topic to another, building on previous knowledge, making connects to new content. It would be easy for instructors to "jump around" the index per their liking.

Modularity rating: 5

The text is broken into appropriate sections, allowing for charts, figures, and links for further understanding. I feel there are no disruptions to the reader.

Organization/Structure/Flow rating: 5

The topics are organized in a logical and clear manner.

Interface rating: 2

The text has many significant interface issues. Although images and charts are displayed nicely, there were several navigational problems throughout including several articles and/or videos that have broken links. Overall, the text is visually appealing.

Grammatical Errors rating: 5

I did not observe any spelling or grammatical errors.

Cultural Relevance rating: 5

The text is not culturally insensitive or offensive in any way and provides diets from various cultures. It could be used by any student.

Reviewed by Beverly Moellering, Assistant Professor/Director Coordinate Program in Dietetics, University of Saint Francis on 5/20/22

The text covers the appropriate topics for an introduction course in nutrition. read more

The text covers the appropriate topics for an introduction course in nutrition.

Content Accuracy rating: 4

Nutrition is continually advancing. There are some topics that are outdated such as the dietary guidelines and reference to Healthy People 2020 to name a couple.

The logical nature of each chapter in the book as well as the progression of topics allow students to have a good understanding of nutrition. Updates just need to occur.

Clarity rating: 4

The book does a good job of explaining key terms and avoids any extreme terminology. Web links are provided to clarify information, but several of the links do not work.

Big ideas, key take aways, and discussion starters throughout each chapter are great tools to help students become engaged with the content.

Modularity rating: 4

The text is organized well and flows easily. At the end of each chapter there are end of chapter exercises which allows the reader to go through items to expand comprehension of topics discussed. Links just do not always work.

It is organized in presenting the key concepts and the six classes of nutrients.

Interface rating: 3

Links to videos, articles, etc. often did not work.

There were no grammar issues with this textbook

No cultural biases found.

While this text book has a good outline of topics covered and ways to engage the reader, the issues with current updates and accurate web links need to be improved. This would be a good supplement text for a course.

Reviewed by Shyanne Sansom, Instructor, Eastern New Mexico University on 1/13/22

The textbook covers all the important topics that a human nutrition text should cover. read more

The textbook covers all the important topics that a human nutrition text should cover.

The book was accurate in 2012, but knowledge of nutrition science changes so quickly that the book is quite outdated in 2022. This was the most challenging aspect of using this for a higher education class. I spent a great deal of time finding accurate, current information for my students.

Relevance/Longevity rating: 3

This textbook is so old that much of the content is obsolete. This makes using it as the primary source of information for a nutrition course extremely challenging.

The textbook is easy to read and accessible for most first year college students.

Chapters are easy to follow, and each chapter is organized so information can be found quickly.

One of the best things about this textbook is how well the sections are organized. Headings a clear, and each section has "key takeaways" and "discussion starters".

Organization/Structure/Flow rating: 3

I did not like the approach the authors used to organize the chapters in the book. Carbohydrates, Lipids and Proteins each had their own chapter, but the authors divided vitamins and minerals into function, rather than vitamin/mineral identity. It does not work as well as other nutrition textbooks, which dedicate individual chapters to vitamins and minerals separately.

None of the links to videos, articles, etc. work in this textbook. Students become very frustrated when they cannot access additional information to support the chapter. I tried to provide alternate sources for the links, but it was incredibly time-consuming.

There were not grammatical problems with this textbook.

Cultural Relevance rating: 4

The book does a good job in chapter 14 of providing multiple perspectives on nutrition. I wish all nutrition textbooks included this. However, the textbook would have been even better if they had included more cultural perspectives throughout every chapter, instead of putting it in just one near the end.

I would not recommend this book to professors hoping to find one good textbook for their human nutrition class. It does provide good basic nutrition information, but a lot of the science is so outdated that you will have to spend a good deal of time updating the information for you students. Additionally, none of the in-text links to videos and articles work. I also did not like the way the authors split the micronutrient chapters into function, rather than type. It is much better to have chapters dedicated to minerals and vitamins instead. Lastly, there are no instructor materials (test banks, PowerPoints, etc.) which also takes more of the instructor's time to create. This is a good supplemental book for a nutrition course, but I would not use this again as the only textbook in a college course.

Reviewed by Amanda Margolin, Adjunct faculty, Portland Community College on 5/26/21

I found that the text covered the subject matter in an appropriate way. I appreciated how there were videos included when more challenging concepts were being discussed such as digestion and absorption. I also found the images used to be effective... read more

Comprehensiveness rating: 4 see less

I found that the text covered the subject matter in an appropriate way. I appreciated how there were videos included when more challenging concepts were being discussed such as digestion and absorption. I also found the images used to be effective in enhancing the text. I found the organization of material to help with the comprehension of the material such as in the section devoted to carbohydrates, information about diabetes was included. If I were to implement this text I would expand on the "antioxidant" section in the chapter about vitamins as I found this section to be quite brief. Some of the sections on minerals do not provide food sources such as the section on the copper, I would include this information so the material is consistent and thorough. In chapter 10 I would include more information related to fuel sources during different types of exercise such as which fuel source our body turns to for jogging vs. sprinting. In 11.3 "Infancy Nutrition" I would include more up to date in formation related to food allergies such as the new science behind when to introduce peanut butter. Some of the chapters such as, chapters 11 and 12 were well written chapters in the text in terms of providing enough content to fully understand the subject where other chapters I feel I would need to expand on the content to provide a more thorough understanding of the material such as Chapters 10 (section 10.3) sports nutrition was quite brief.

The content presented in this text is accurate and references are provided throughout the text. The content did not present any bias issues.

Overall this information from this text is up to date. The current dietary guidelines focus on 2020-2025 which is our most up to date guidelines released from the government. This text uses information from the 2015 guidelines. This is something I would need to update for my course in order to have the most up to date information related to our guidelines. Similarly, we have information for Healthy People 2030, this text uses information from Healthy People 2020. The text also uses a picture of the old nutrition facts panel when discussing how to read a label. I would include the up to date nutrition facts panel if I implement this text for my course. I thought the section about sugar substitutes and added sugars was very relevant to today's culture. The progression of material will make it easy as an instructor for me to implement for my course.

The information is presented in a clear and logical way making it easy for the reader to follow along and move section to section through the material. At the end of each section there is a "Key Takeaway" section which provides nice summary points for the reader. At the end of each section there is also a "Discussion starter" section which provides the reader with thought-provoking questions to increase understanding of the material. I appreciated how within the text you will find references to material from previous chapters such as in 9.1 "Metabolism overview" there is a reference to material covered from chapter 6.

The text is consistent from chapter to chapter as well as section to section within each chapter. The same organizational structure is used for each section providing consistency throughout the text.

The text is organized and flows nicely for the reader from chapter to chapter. Each chapter is broken down into sections. Each section begins with learning objectives and ends with "key takeaways and discussion starters" to enhance the material presented in the text. At the end of each chapter there is a section "It's your turn" which allows the reader to go through example quiz questions and discussion questions to expand knowledge.

The book begins with more introductory topics such as "Nutrition and you" and "A healthy diet" which provides students terminology and some nutrition basics. From there the chapters are presented in a logical way, building on material as the text goes on. For example, chapter 3 delves into metabolism/digestion/absorption where the following chapters focus on macronutrients specifically as they relate to these processes.

Interface rating: 5

I did not notice any significant interface issues. The text was easy to navigate and all of the images and videos appeared appropriately free of distortion within the text.

I did not notice any grammatical errors when reviewing the text.

The text mentions cultural as it relates to food choices. There is also a section in chapter 2 about "diets around the world" focusing on food culture from other regions.

Reviewed by Chimene Castor, Associate Professor, Howard University on 4/29/21

It comprehensive for an introductory book in nutrition. The clinical nutrition information should be more comprehensive, but the instructor can additional reading materials read more

Comprehensiveness rating: 3 see less

It comprehensive for an introductory book in nutrition. The clinical nutrition information should be more comprehensive, but the instructor can additional reading materials

Nutrition is a progressive field and needs continuous revision - this textbook is updated

Yes, it is updated with necessary content

The book is well organized in the necessary material to review with students.

Missing food analysis component

Organization/Structure/Flow rating: 4

Yes, the materials are well presented but need to have a diverse groups

Grammatical Errors rating: 4

The book is clear for students to understand.

A more diverse group can be used to represent the global community.

Food analysis for nutrients and food frequency; missing global BMI for children to compare with CDC

Reviewed by Anne Goodwin, Professor, Massachusetts College of Liberal Arts on 6/30/20

This book provides a good overview of nutrition for the non-major; topics such as nutrition for athletes and global food security are largely omitted, and information about the current dietary guidelines for Americans will need to be provided as... read more

This book provides a good overview of nutrition for the non-major; topics such as nutrition for athletes and global food security are largely omitted, and information about the current dietary guidelines for Americans will need to be provided as supplemental information.

No errors were noted in the reviewed material.

Relevance/Longevity rating: 5

Since nutrition is a constantly evolving science, current information will always need to be added, but this book is formatted in a way that will allow this to be added.

I believe this text has clarity appropriate to the non-major student.

The organization is consistent and well-suited to the topic and audience.

The sections are easily accessed through the index and can be presented in an alternate order as desired by the instructor.

The topics are ordered in a fashion similar to that found in other nutrition textbooks.

In the book sections used so far, no interface issues were noted.

In the book sections used so far, no issues with grammar.

The section on international diets is a welcome addition; other cultural aspects may need to be addressed by the instructor in greater detail.

I am adopting this text for use, with supplemental materials, for my non-majors nutrition course.

Reviewed by Sharron Guillett, Full Professor, Shenandoah University on 6/18/20

The book is comprehensive and covers all aspects of nutrition across the life span as well as issues related to policy and sustainability. The chapters related to chronic diseases and eating habits around the world are particularly well done. read more

The book is comprehensive and covers all aspects of nutrition across the life span as well as issues related to policy and sustainability. The chapters related to chronic diseases and eating habits around the world are particularly well done.

Content Accuracy rating: 3

The book is accurate in content areas that address the basics of nutritional science. For example, the information about nutrients, how they are used to support health and the foods in which they can be found is accurate. Conclusions/opinions presented by the authors about relationships between nutrients and or eating behaviors and health are sometimes inaccurate, overly simplified or overly generalized. For example, the statement that diabetes is caused by diet is not true. Diet is only one of many contributing factors. Similarly, the statement that "to do all of the things that you like to do are dependent upon one factor—your health" is an over simplification that serves as bias toward nutrition as "the one" factor necessary for good health and good living

The factual components of the text are current and easily updated thanks to the modular format of the text. The real issue is that rather than having resources and references at the end of chapter sections, they are embedded in the text making it not only challenging to read but also challenging and cumbersome to update the links that are no longer working. Some material related to dietary trends and fads needs to be updated and some notions about age groups have changed over time. For example people aged 51 are no longer considered "older adults".

The prose is clear , free of jargon and based on the "SMOG method", written at an 11th to 12th grade level. Definitions are also provided where needed. No glossary.

The book is consistent in format, framework and terminology.

The book is designed as a modular text. There are assignments/activities at the end of each section within the chapters that make it easy to use the text in a variety of course delivery methods/timelines.

The book is organized in a logical fashion moving from simple to complex. Chapter divisions make it easy for the reader to assess their knowledge in manageable chunks.

The text integrates the narrative with both internal and external links . Most of the external links are broken and take the reader to pages that either don't exist or are "deep links" that require a great deal of searching to locate. Even the Appendix which is a link to dietary requirements is broken. Many of the internal links seem unnecessary or inappropriate. For example there is a discussion of the nutritional triad (social, physical, mental) and an internal link takes the reader to a picture of three women in yoga poses pointing at the words social, physical,mental.

The text is free of spelling and grammatical errors.

The book uses images of persons from a variety of races, genders and ages. No offensive language or cultural references were noted.

This book is like a classic car that no longer runs but still has value in its parts. There are segments, tables and charts that could be "harvested" and used to support learning about nutrients , their sources and and how healthy eating is life sustaining.

Reviewed by Nicole Stob, Instructor, University of Colorado Boulder on 6/11/20

All areas of the subject were covered appropriately. Terms were defined throughout the text, but a comprehensive glossary or index was not found. read more

All areas of the subject were covered appropriately. Terms were defined throughout the text, but a comprehensive glossary or index was not found.

The vast majority of the content was accurate, but some of the content needs to be updated and therefore not accurate.

The vast majority of the content was up-to-date, but some of the content needs to be updated. For example, content relating to the nutrition facts label is not updated.

The writing is clear and easy to understand. Adequate context is provided.

The text is internally consistent, using the same terminology and framework throughout.

The text is broken up appropriately, allowing for breaks in the reading with links to outside resources, figures, etc.

The topic are organized in a logical manner.

Several broken links to outside resources were found in chapters 1-3 (none of the other chapters' links were checked).

No grammatical errors were noted in the text.

The text is culturally sensitive and does a nice job of using examples from different cultures and exploring the diets of different cultures as well.

Reviewed by Mahdi Garelnabi, Associate Professor, University of Massachusetts Lowell on 6/7/20

The authors comprehensively covered the topics from all aspects. read more

The authors comprehensively covered the topics from all aspects.

Quite accurate information

The book is timely and relevant to the area of human nutrition

Authors used very easy and clear language to follow

pretty good consistency.

The text is very rich with background, at some point lay language is used for better understanding.

The book is well organized. It is divided into broader chapters and small topics with each chapters

The text is certainly free from from and interface issues. Figures and images are clear. The book is nicely displayed.

No grammatical mistakes was seen

No cultural sensitive item was observed.

This is a great book to adopt for human nutrition.

Reviewed by Clare McEnroe, Adjunct Professor, Raritan Valley Community College on 3/25/20

The textbook does cover the surface of many topics important for students to know and understand and can use. read more

The textbook does cover the surface of many topics important for students to know and understand and can use.

The information is unbiased. There needs to be some updating to some of the content. As in any science field, nutrition keeps changing and there would need to be some supplements added to this text to bring it up to date. This would definitely be possible to do by the instructor.

There are some links that no longer work and would need to be updated. Also there has been some new information that can be added in terms of fad diets and diet trends that are new since the text has been written.

The language/terminology used is appropriate for an introduction course and mainly taken by students who are not science majors and just want some background information about nutrition.

The set up of each chapter has a good flow and easy to understand.

The chapters are set up as if you can use them in that order but wouldn't matter if they were used out of order either. They are pretty much separate topics but can also be related.

Each topic is very clear and covers the majority of the information for an introduction course. Understandable and usable information is presented.

Interface rating: 4

Some links do not work and may need to replaced or updated with newer information.

I did not notice grammatical errors.

The textbook can be used by anyone, There is no cultural insensitivity at all.

This is a textbook to consider for an Introduction course. The updates and additional topics could be supplemented without a problem.

Reviewed by Caleb Bazyler, Assistant Professor, East Tennessee State University on 3/4/20

The textbook does an excellent job fulfilling its purpose of communicating nutrition content to a novice audience with a non-science background. The table of contents appropriately links content provided in each chapter including subtitles and end... read more

The textbook does an excellent job fulfilling its purpose of communicating nutrition content to a novice audience with a non-science background. The table of contents appropriately links content provided in each chapter including subtitles and end of chapter exercises.

The content was accurate and unbiased. Controversial topics were handled fairly with all opinions presented. I appreciated the functional approach discussing nutrition in the context of different bodily systems. This is very intuitive for an introductory level course.

Much of the basic science content will not need to be updated, and sections that will need to be updated (e.g. reference intakes, results from pending clinical trials, updates on controversial topics) should not be difficult to edit.

All key terms are in bold throughout the textbook and carefully defined. I also appreciated the external links to video explanations where relevant.

The text is internally consistent in regard to terminology and structure. The section and subsection layout was easy to follow throughout.

The chapter sections and subsections are easy to follow, and the authors do a great job building on content discussed in earlier chapters. The key takeaways and discussion segments at the end of each chapter are a great way to connect readers with the content, and provide topics of conversation in the classroom.

The topics are presented in a logical manner consistent with other nutrition textbooks.

While the text was mostly easy to navigate, I would have also appreciated a small table of contents at the beginning of each chapter with links to different parts of the chapter. This would make each chapter much easier to navigate. Also, some of the external links were broken, and some tables were not fully viewable (e.g. Tables 2.12 and 4.7).

I did not notice any grammatical errors.

The content at the end of the textbook on food industry, politics, cost and security was an excellent addition. I also appreciated the comparisons of diets across cultures, and pros/cons of popular dietary regiments.

Reviewed by Meagan Helmick, Assistant Professor of Public Health, Radford University on 1/6/20

This text does a good job at providing students with information about macro- and micro-nutrients and how they work in your body. It also covers nutrition at different life stages. The target audience is well thought about in this book, and is... read more

This text does a good job at providing students with information about macro- and micro-nutrients and how they work in your body. It also covers nutrition at different life stages. The target audience is well thought about in this book, and is needed for students that are not nutrition majors.

I did not notice any inaccuracies.

This text is up-to-date, but will need to be updated when the new Dietary Guidelines are published. However, this is something that I, as an instructor, can supplement to my students. The logical nature of each chapter in the book as well as the overall progression allows for students to have a well rounded understanding of nutrition.

The textbook does a good job of explaining key terms as the person is reading (on the left side of the page), and avoids any extreme use of terminology that students might not be able to grasp.

The chapters are set up the same way, which helps the reader to know what to expect as they progress through the textbook. The key takeaways and discussion starters are great tools to help students understand what they are reading and can serve as prompts in class for discussion. The end of the chapter exercises also provide this opportunity to engage with the reading and make sure students comprehended the information.

The sections are broken down into appropriate sizes by topics. I like that the table of contents include the sections as well. This helps students quickly find the information they are looking for.

Overall the organization is well thought out. Each chapter has components that build on previous chapters, but not in such a way that doesn't allow you to skip chapters or reorder the readings.

The charts and for some of the chapters were cut off, I think this is likely because this was designed with a book-binding format, but I was still able to read the information and understand what it intended to state. Appendix A's link did not work when I clicked on it to see the DRI tables.

No issues that I noted.

Chapter 14 does a good job of highlighting "Diets Around the World" which provides different cultural takes on diets. I did not note anything insensitive.

Reviewed by Tina Moody, Biology Faculty, Northland Community and Technical College on 7/1/19

For the target audience, the book is right on track. It doesn't assume one has a chemistry or biology background - perfect for my nutrition course. read more

For the target audience, the book is right on track. It doesn't assume one has a chemistry or biology background - perfect for my nutrition course.

I didn't see any incorrect information.

The book is fairly up to date (available since the end of 2012) but with this level of textbook and its information it isn't likely to change much. Any new information is something that I try to incorporate into my class materials regardless of the textbook source. When the FNB publishes new guidelines in 2020, I will be able to update these for my students easily.

I like how important terms are defined on the left side of the page.

Each of the chapters is set up the same way making it very intuitive once a student becomes familiar with the textbook. I believe the 'Key Takeaways' and 'Discussion Starters' at the end of each section and the 'End-of-Chapter Exercises' will help students insure they truly understood what they just read.

The way each chapter is broken down into sections will work well for my class. Each section is listed in the Table of Contents as well, making it even easier for students to find what they need. The 'End-of-Chapter Exercises' are even in the TOC.

Occasionally there are topics I have tackled in a slightly different order in the past (vegetarianism after a discussion of protein structure and function for example) but that's just personal taste.

The only issue I had with some of the charts is that some of the acronyms in the chart were not explained in the description. Some of the writing was small as well, though I'm not sure how the authors could have dealt with that and still had a good flow of information rather than flipping back and forth between pages to see a larger chart.

I did not see any grammatical errors.

I feel the textbook did well in this area. Chapter 14 Politics and Perspectives covered the globe well in the 'Diets around the World' section.

Table of Contents

• Chapter 1: Nutrition and You
• Chapter 2: Achieving a Healthy Diet
• Chapter 3: Nutrition and the Human Body
• Chapter 4: Carbohydrates
• Chapter 5: Lipids
• Chapter 6: Proteins
• Chapter 7: Nutrients Important to Fluid and Electrolyte Balance
• Chapter 8: Nutrients Important As Antioxidants
• Chapter 9: Nutrients Important for Bone Health
• Chapter 10: Nutrients Important for Metabolism and Blood Function
• Chapter 11: Energy Balance and Body Weight
• Chapter 12: Nutrition through the Life Cycle: From Pregnancy to the Toddler Years
• Chapter 13: Nutrition through the Life Cycle: From Childhood to the Elderly Years
• Chapter 14: Nutrition and Society: Food Politics and Perspectives
• Chapter 15: Achieving Optimal Health: Wellness and Nutrition
• Chapter 16: Appendix A

Ancillary Material

About the book.

Welcome to Essentials of Nutrition: A Functional Approach! This book is written for students who are not majoring in nutrition, but want to learn about the fundamental aspects of nutrition and how it applies to their own lives. We have written this book with the assumption that you have little or no prior knowledge of college level chemistry, biology, or physiology. But that does not mean it’s not scientific! Nutrition is a science-based discipline, so all the material included is backed up by rigorous scientific research, but it is presented in a clear, easy-to-understand fashion without requiring a background in science.

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1.1: Introduction to Nutrition

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• University of Hawai’i at Mānoa

Chapter Skills to Develop

• Describe basic concepts in nutrition
• Describe factors that affect your nutritional needs
• Describe the importance of research and scientific methods to understanding nutrition

ʻO ke kahua ma mua, ma hope ke kūkulu

The foundation comes first, then the building

What are Nutrients?

Nutrients are substances required by the body to perform its basic functions. Most nutrients must be obtained from our diet, since the human body does not synthesize or produce them. Nutrients have one or more of three basic functions: they provide energy, contribute to body structure, and/or regulate chemical processes in the body. These basic functions allow us to detect and respond to environmental surroundings, move, excrete wastes, respire (breathe), grow, and reproduce.

There are six classes of nutrients required for the body to function and maintain overall health. These are: carbohydrates, lipids, proteins, water, vitamins, and minerals. Nutritious foods provide nutrients for the body. Foods may also contain a variety of non-nutrients. Some non-nutrients such as as antioxidants (found in many plant foods) are beneficial to the body, whereas others such as natural toxins (common in some plant foods) or additives (like certain dyes and preservatives found in processed foods) are potentially harmful.

Macronutrients

Nutrients that are needed in large amounts are called macronutrients. There are three classes of macronutrients: carbohydrates, lipids, and proteins . Macronutrients are carbon-based compounds that can be metabolically processed into cellular energy through changes in their chemical bonds. The chemical energy is converted into cellular energy known as ATP , that is utilized by the body to perform work and conduct basic functions.

The amount of energy a person consumes daily comes primarily from the 3 macronutrients. Food energy is measured in kilocalories. For ease of use, food labels state the amount of energy in food in “calories,” meaning that each calorie is actually multiplied by one thousand to equal a kilocalorie. (Note: Using scientific terminology, “Calorie” (with a capital “C”) is equivalent to a kilocalorie. Therefore: 1 kilocalorie = 1 Calorie - 1000 calories

Water is also a macronutrient in the sense that the body needs it in large amounts, but unlike the other macronutrients, it does not contain carbon or yield energy.

Note: Consuming alcohol also contributes energy (calories) to the diet at 7 kilocalories/gram, so it must be counted in daily energy consumption. However, alcohol is not considered a "nutrient" because it does not contribute to essential body functions and actually contains substances that must broken down and excreted from the body to prevent toxic effects.

Carbohydrates

Carbohydrates are molecules composed of carbon, hydrogen, and oxygen that provide energy to the body. The major food sources of carbohydrates are milk, grains, fruits, and starchy vegetables, like potatoes. Non-starchy vegetables also contain carbohydrates, but in lesser quantities. Carbohydrates are broadly classified into two forms based on their chemical structure: simple carbohydrates (often called simple sugars) and complex carbohydrates.

Simple carbohydrates consist of one or two basic sugar units linked together. Their scientific names are "monosaccharides" (1 sugar unit) and disaccharides (2 sugar units). They are broken down and absorbed very quickly in the digestive tract and provide a fast burst of energy to the body. Examples of simple sugars include the disaccharide sucrose, the type of sugar you would have in a bowl on the breakfast table, and the monosaccharide glucose, the most common type of fuel for most organisms including humans. Glucose is the primary sugar that circulates in blood to provide energy to cells. The terms "blood sugar" and "blood glucose" can be substituted for each other.

Complex carbohydrates are long chains of sugars units that can link in a straight chair or a branched chain. During digestion, the body breaks down digestible complex carbohydrates into simple sugars, mostly glucose. Glucose is then absorbed into the bloodstream and transported to all our cells where it is stored, used to make energy, or used to build macromolecules. Fiber is also a complex carbohydrate, but it cannot be broken down by digestive enzymes in the human intestine. As a result, it passes through the digestive tract undigested unless the bacteria that inhabit the colon or large intestine break it down.

One gram of digestible carbohydrates yields 4 kilocalories of energy for the cells in the body to perform work. In addition to providing energy and serving as building blocks for bigger macromolecules, carbohydrates are essential for proper functioning of the nervous system, heart, and kidneys. As mentioned, glucose can be stored in the body for future use. In humans, the storage molecule of carbohydrates is called glycogen, and in plants, it is known as starch. Glycogen and starch are complex carbohydrates.

Lipids are also a family of molecules composed of carbon, hydrogen, and oxygen, but unlike carbohydrates, they are insoluble in water. Lipids are found predominantly in butter, oils, meats, dairy products, nuts, and seeds, and in many processed foods. The three main types of lipids are triglycerides (triacylglycerols), phospholipids, and sterols. The main job of triacylglycerols is to provide or store energy. Lipids provide more energy per gram than carbohydrates (9 kilocalories per gram of lipids versus 4 kilocalories per gram of carbohydrates). In addition to energy storage, lipids serve as a major component of cell membranes, surround and protect organs (in fat-storing tissues), provide insulation to aid in temperature regulation. Phospholipds and sterols have a somewhat different chemical structure and are used to regulate many other functions in the body.

Proteins are macromolecules composed of chains of basic subunits called amino acids. Amino acids are composed of carbon, oxygen, hydrogen, and nitrogen. Food sources of proteins include meats, dairy products, seafood, and a variety of different plant-based foods, most notably soy. The word protein comes from a Greek word meaning “of primary importance,” which is an apt description of these macronutrients; they are also known colloquially as the “workhorses” of life. Proteins provide the basic structure to bones, muscles and skin, enzymes and hormones and play a role in conducting most of the chemical reactions that take place in the body. Scientists estimate that greater than one-hundred thousand different proteins exist within the human body. The genetic codes in DNA are basically protein recipes that determine the order in which 20 different amino acids are bound together to make thousands of specific proteins. Because amino acids contain carbon, they can be used by the body for energy and supply 4 kilocalories of energy per gram; however providing energy is not protein’s most important function.

There is one other nutrient that we must have in large quantities: water. Water does not contain carbon, but is composed of two hydrogen atoms and one oxygen atom per molecule of water. More than 60 percent of your total body weight is water. Without water, nothing could be transported in or out of the body, chemical reactions would not occur, organs would not be cushioned, and body temperature would widely fluctuate. On average, an adult consumes just over two liters of water per day from both eating foods and drinking liquids. Since water is so critical for life’s basic processes, total water intake and output is supremely important. This topic will be explored in detail in Chapter 4.

Micronutrients

Micronutrients are also essential for carrying out bodily functions, but they are required by the body in lesser amounts. Micronutrients include all the essential minerals and vitamins . There are sixteen essential minerals and thirteen essential vitamins (See Table \(\PageIndex{1}\) and Table \(\PageIndex{2}\) for a complete list and their major functions).

In contrast to carbohydrates, lipids, and proteins, micronutrients are not sources of energy (calories) for the body. Instead they play a role as cofactors or components of enzymes (i.e., coenzymes) that facilitate chemical reactions in the body. They are involved in all aspects of body functions from producing energy, to digesting nutrients, to building macromolecules. Micronutrients play many essential roles in the body.

Minerals are solid inorganic substances that form crystals and are classified depending on how much of them we need. Trace minerals, such as molybdenum, selenium, zinc, iron, and iodine , are only required in a few milligrams or less. Macrominerals, such as calcium, magnesium, potassium, sodium, and phosphorus , are required in hundreds of milligrams. Many minerals are critical for enzyme function, while others are used to maintain fluid balance, build bone tissue, synthesize hormones, transmit nerve impulses, contract and relax muscles, and protect against harmful free radicals in the body that can cause health problems such as cancer.

The thirteen vitamins are categorized as either water-soluble or fat-soluble. The water-soluble vitamins are vitamin C and all the B vitamins, which include thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folate and cobalamin. The fat-soluble vitamins are A, D, E, and K . Vitamins are required to perform many functions in the body such as assisting in energy production, making red blood cells, synthesizing bone tissue, and supporting normal vision, nervous system function, and immune system function.

Vitamin deficiencies can cause severe health problems and even death. For example, a deficiency in niacin causes a disease called pellagra, which was common in the early twentieth century in some parts of America. The common signs and symptoms of pellagra are known as the “4D’s—diarrhea, dermatitis, dementia, and death.” Until scientists discovered that better diets relieved the signs and symptoms of pellagra, many people with the disease ended up hospitalized in insane asylums awaiting death. Other vitamins were also found to prevent certain disorders and diseases such as scurvy (vitamin C), night blindness (vitamin A), and rickets (vitamin D).

Contributor

University of Hawai’i at Mānoa Food Science and Human Nutrition Program : Allison Calabrese, Cheryl Gibby, Billy Meinke, Marie Kainoa Fialkowski Revilla, and Alan Titchenal

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1.1 – Introduction to Nutrition

Nutrition is an evidence-based science that studies how the nutrients and compounds in foods nourish and affect body functions and health .

Nutritional scientists continuously advance our knowledge of nutrition by building on prior research.

Video 1.1.1 : Nutrition Quiz: Listen to what Americans think 100 Calories looks like .

Let’s start out our journey into the world of health and nutrition, by demonstrating that nutritional science is an evolving field of study, continually being updated and supported by research, studies, and trials. Once we establish this, your confidence will be strengthened in nutritional science to help guide your eating habits. Let’s begin with the story of hurry, curry, and worry: the story of Helicobacter (H.) pylori.

Peptic ulcers are painful sores in the gastrointestinal tract and can cause symptoms of abdominal pain, nausea, loss of appetite, and weight loss. The cure for this ailment took some time for scientists to figure out. If your grandparents complained to their doctor of symptoms of peptic ulcer, they were probably told to avoid spicy foods, alcohol, and coffee, and to manage their stress. In 1915, Dr. Bertram W. Sippy devised the “Sippy diet” for treating peptic ulcers. Dr. Sippy advised patients to drink small amounts of cream and milk every hour in order to neutralize stomach acid. And then, increasingly, introduce soft bland foods with frequent mealtimes. For a while this diet sometimes worked, fooling both doctors and patients. However, the disappearance of peptic ulcer symptoms was likely the result of having a full stomach all the time, as the symptoms more often occur when the stomach is empty. Ultimately, the Sippy diet did not cure peptic ulcers and in the latter 1960s, scientists discovered the diet was associated with a significant increase in heart disease due to its high saturated fat content.

In 1994-The National Institutes of Health held a conference on the cause of peptic ulcers. There was scientific consensus that H. pylori cause most peptic ulcers and that patients should be treated with antibiotics.

In 1996-The Food and Drug Administration (FDA) approved the first antibiotic that could be used to treat patients with peptic ulcers. Nevertheless, the link between H. pylori and peptic ulcers was not sufficiently communicated to healthcare providers. In fact, 75 percent of patients with peptic ulcers in the late 1990s were still being prescribed antacid medications and advised to change their diet and reduce their stress.

In 1997-The Centers for Disease Control and Prevention (CDC), alongside other public health organizations, began an intensive educational campaign to convince the public and healthcare providers that peptic ulcers are a curable condition requiring treatment with antibiotics. Today, if you go to your primary physician you will be given the option of taking an antibiotic to eradicate H. pylori from your gut. Scientists have progressed even further and mapped the entire genome of H. pylori, which will hopefully aid in the discovery of even better drugs to treat peptic ulcers.

In 2005, Marshall and Warren were awarded the prestigious Nobel Prize in medicine for their discovery that many stomach ulcers are caused by H. pylori—not by hurry, curry, and worry.

Make a commitment to empower yourself with scientific evidence as a strategy for achieving a healthier diet.

In this chapter, you will see that there are many conditions and deadly diseases that can be prevented by good nutrition. You will also discover the many other determinants of health and disease, how the powerful tool of scientific investigation is used to design dietary guidelines, how to spot nutrition myths, quackery, and fraud, and how to locate nutrition experts and accurate nutrition information.

Nutrition 100 Nutritional Applications for a Healthy Lifestyle Copyright © by Lynn Klees is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Chapter 1: Introduction to Nutrition

“Let food be thy medicine, and medicine be thy food.” -Hippocrates, referred to as the “Father of  Modern Medicine”

Life depends on nourishment and the quality of life depends greatly on the foods you choose to eat. Any discussion of nutrition must begin with an understanding of nutrition, nutrients, and their overall relationship to health and well-being.

Learning Objectives

• Define health, nutrition, and disease.
• List and describe the characteristics used to assess your health status.
• Differentiate among risk factors, signs, and symptoms.
• Define the word “nutrient” and differentiate among the six classes of nutrients essential for health.
• Explain how energy values of food are determined, and list the three energy-yielding nutrients and their energy contribution.
• Describe measures of food quality and be able to calculate and compare energy densities of foods.
• Describe the importance of research and scientific methods to understanding nutrition.
• Analyze sources of nutrition information for reliability and credibility.

1.1 Defining Nutrition, Health, and Disease

The word nutrition first appeared in 1551 and comes from the Latin word nutrire, meaning “to nourish.” Today, we define nutrition as the sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes. Nutritional science is the investigation of how an organism is nourished, and incorporates the study of how nourishment affects personal health, population health, and planetary health. Nutritional science covers a wide spectrum of disciplines. As a result, nutritional scientists can specialize in particular aspects of nutrition such as biology, physiology, immunology, biochemistry, education, psychology, sustainability, and sociology.

Without adequate nutrition the human body does not function optimally, and severe nutritional inadequacy can lead to disease and even death. The typical American diet contains adequate calories, but is lacking in many ways, from not containing the proper amounts of essential nutrients, to being too speedily consumed, to being only meagerly satisfying.

Registered Dietitians (RD), also called Registered Dietitian Nutritionists (RDN), are nutrition professionals who integrate their knowledge of nutritional science into helping people achieve a healthy diet and develop good dietary habits. Through their knowledge and experiences, RDs/RDNs specialize in translating nutrition science into practical advice. Becoming an RD/RDN requires a college degree with an emphasis in chemistry, anatomy and physiology, and other sciences, the completion of a 1200-hour dietetic internship in clinical and community settings, and passing the national certification exam. Once you achieve RD/RDN status, you must complete 75-hours of continuing education in nutrition every five years. RDs/RDNs work in many diverse settings including hospitals, clinics, long-term care facilities, schools, health clubs, grocery stores, private practice, insurance companies, and corporate wellness programs. They can help you overcome disordered eating, set realistic weight loss and weight management goals, manage chronic diseases, or help you achieve optimal athletic performance. The Academy of Nutrition and Dietetics (AND) is the largest organization of nutrition professionals in the world and dietitians registered with the AND are committed to helping Americans eat well and live healthier lives. To learn more about the AND and their nutritional advice for consumers, visit eatright.org .

Nutrition and Health and Disease

Your ability to wake up, to think clearly, to communicate, to hope, to dream, to go to school, to gain knowledge, to go to work, to earn a living, and to do all of the things that you like to do are dependent upon one factor—your health. Good health means you are able to function normally and work hard to achieve your goals in life. In 1946, the World Health Organization (WHO) defined health as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.” 1 This definition was adopted into the WHO constitution in 1948 and remains to this day. A triangle is often used to depict the equal influences of physical, mental, and social well-being on health.

Disease is defined as any abnormal condition affecting the health of organisms and typically characterized by specific signs and symptoms. Diseases are broadly categorized as resulting from pathogens (i.e., bacteria, viruses, fungi, and parasites), deficiencies, genetics, and/or physiological dysfunction. Diseases that primarily affect physical health are those that impair body structure (as is the case with osteoporosis), or functioning (as is the case with cardiovascular disease). Mental illnesses primarily affect mental and social well-being.

The foods we eat affect multiple aspects of our health. For example, a teen with type 2 diabetes (a disease often brought on by poor diet and lack of physical activity) is first diagnosed by physical signs and symptoms such as increased urination, excessive thirstiness, and unexplained weight loss. But research has also found that teens with uncontrolled type 2 diabetes often have impaired thinking and may not interact well with others in school, thereby affecting mental and social well-being. This is just one example of a physiological disease that can affect physical, mental, and social aspects of health.

In the early twentieth century, most nutrition-related diseases and conditions were related to inadequate calorie consumption or deficiency of nutrients. In the latter part of the twentieth century nutrition scientists, public health organizations, and the American public increasingly recognized that eating too much of certain foods is linked to chronic diseases. Table 1.1.1 shows the top ten causes of death in the US. As you can see, many of these causes are related to nutrition. We now know that diet-related conditions and diseases include but are not limited to cardiovascular (heart) diseases including hypertension (high blood pressure) and stroke, obesity, type 2 diabetes, several forms of cancer, and osteoporosis.

Table 1.1.1 United States Leading Causes of Death 2017 & 2018 in deaths per 100,000 US Standard Population 2

1.2 assessing your health.

There are many factors that determine whether you are “healthy.” Although the WHO definition describes health as not just the absence of disease, but also encompassing psychological, emotional, and social well-being, most of Western medicine is focused on a person’s physical health. As we have discussed previously, and will continue to discuss throughout this course, nutrition plays an enormous role in determining our overall health. Assessing one’s nutritional status can help us determine whether nutritional intake (or lack of) is affecting the development or continuance of nutrition-related health conditions. No one eats 100% healthy foods 100% of the time, but with assessment we look at the overall eating pattern and how it affects overall health. Nutrition assessment uses many tools to help determine whether a person is well-nourished or malnourished (referring to either undernourished or overnourished).

There are six areas to consider when assessing health through a nutrition lens. An easy way to remember these areas is using the letters ABCDEF:

A:  anthropometric

B:  biochemical

C:  clinical

D:  dietary

E:  environmental

F:  family history

A: Anthropometric Assessment

The word anthropometric comes from two terms: anthropo meaning “human” and metric meaning “measure.” There are many different measures used to assess growth in humans including height, weight, body mass index (BMI), head circumference, girth measurements of limbs, waist, hip, and body composition measures such as skinfold/fat fold thickness or bioelectrical impedance analysis. We then compare those measures to known health standards. Often these types of measurements are used to assess the growth of children and adolescents. However, some of these measures such as height and weight are used throughout our lifetimes, comparing measurements over time, or comparing one person to another. We will discuss these measures in more detail in Chapter 9 Energy Balance and Chapter 11 Nutrition and Fitness.

B: Biochemical Assessment

Biochemical assessment includes laboratory tests that can measure a nutrient or its metabolites in the blood, urine, feces, or other bodily secretions. We can learn quite a bit about a person’s health by looking at these tests and they are routinely collected and examined as part of a general physical by your doctor. In nutrition, for example, we look at the levels of glucose in the blood and in the urine to determine if a person has or is at risk for diabetes. We look at blood cholesterol profiles to help determine risk for some forms of cardiovascular disease. The amount of iron in the blood can indicate a person’s risk for anemia. It is recommended that you keep copies of your lab tests so that you can look at trends over time.

C: Clinical Assessment

In addition to anthropometric and biochemical measures, clinical signs and symptoms are used to assess nutritional status such as a potential nutrient deficiency or toxicity. Signs are those things that can be easily seen such as bleeding, vomiting, or fainting. Symptoms are those things that a patient may be experiencing that cannot easily be seen and must be described such as a headache, nausea, dizziness, or pain. Special attention is given to a person’s organs such as skin, eyes, tongue, ears, mouth, hair, nails, and gums. Clinical methods of assessing nutritional status involve checking signs at specific points on the body, or asking patients about any symptoms that may indicate a nutrient deficiency. Often other clinical measures such as temperature and blood pressure are also taken.

If a nutrient deficiency is suspected based on signs or symptoms, often a biochemical test is completed to help identify the exact nutrient that may be inadequate or missing. There are two types of nutrient deficiencies a person may develop. A primary nutrient deficiency occurs when a person does not consume enough of an essential nutrient. A secondary nutrient deficiency occurs when enough of the nutrient is consumed, but for some reason the body is unable to use that nutrient effectively. Secondary nutrient deficiencies can occur because of functional problems in the digestive tract, medications that may be interfering with the body’s absorption or metabolism of a particular nutrient, the body’s natural aging process, and many other reasons.

D: Dietary Assessment

Dietary methods of assessment include looking at past and current intake of nutrients from food by individuals or a group to help determine their nutritional status. Completing a dietary assessment is crucial when trying to determine whether or not your intake is related to a disease or condition. There are several methods that may be used to do this:

• 24-hour dietary recall. A trained professional asks a person to recall all food or drink consumed in the previous 24-hours. This is a quick and easy method. However, it is dependent upon the person’s short-term memory and may not be very accurate. It also looks at just one day, which may not be a “typical” day of intake for the individual.
• Food Frequency Questionnaire . The person is given a list of foods and asked to indicate average intake per day, per week, and per month. This method is inexpensive and easy to administer, however it often lacks detail and may not be very accurate. It can still provide a broad overview of one’s overall eating pattern.
• Food Diary . Food intake is recorded at the time of eating. This is also known as a food journal or food record. These diaries can be done with paper and pencil, but are more likely to be recorded using apps on a phone or other electronic device. This method is generally reliable but is difficult to accurately maintain for more than a few days, and portion sizes can be difficult to estimate.
• Observed Food Consumption. This method requires food to be weighed and the nutrient content exactly calculated. It is very accurate, but time consuming and expensive, and is usually done only for research purposes.

E: Environmental Assessment (Lifestyle)

Where and how you live can have a profound effect on your health and nutritional status. Many environmental factors play a role including your living situation (alone, with a family, with friends, etc.), geographic location (urban vs rural, north vs south, etc.), socioeconomic position, access to healthy foods, your ability to prepare food, and other lifestyle factors such as exercise and sleep patterns, emotional health, and work-life balance.

An assessment of your environment includes evaluating not only your nutrition, but also your personal habits. Many diseases are preventable by simply staying away from certain behaviors (smoking, excessive alcohol use, risky sexual activity, etc.). Instead adopt healthful measures like participating in regular physical activity, wearing seat belts in the car and helmets while cycling, and finding healthy ways to minimize your response to stressors like meditation or spending time outdoors. As stated earlier, health is more than just physical. Emotional health is often hard to talk about; however, a person’s quality of life is highly affected by emotional stability. Finding balance between work and life is a difficult and continuous process involving keeping track of your time, taking advantage of job flexibility options, saying no, and finding support when you need it. Work-life balance can influence what you eat too.

F: Family Medical History

Everyone starts out in life with the genes handed down to them from their mother and father. Genes are responsible for your many traits as an individual and are defined as the sequences of DNA that code for all the proteins in your body. The expression of different genes can determine the color of your hair, skin, and eyes, and even if you are more likely to be fat or thin and if you have an increased risk for a certain disease. The sequence of DNA that makes up your genes and determines your genetic makeup is called your genome . In 2003, the Human Genome Project was completed and now the entire sequence of DNA in humans is known. It consists of about three billion individual units and contains between 25,000 and 30,000 genes. The human genome that was sequenced was taken from a small population of donors and is used as a reference DNA sequence for the entire population. Each of us has a similar but unique DNA sequence. Only identical twins and cloned animals have the exact same DNA sequence.

Epigenetics is the study of how your behaviors and your environment may turn genes “on” or “off,” causing changes that can affect how your genes work. In recent years scientists have been studying the possible epigenetic links between genes and nutrients. Initial studies looked at nutrigenomics , the study of the intake of nutrients and their effects on genetic expression in an individual. Not all epigenetic changes are permanent. A beneficial change in nutrient intake, increased physical activity, or quitting smoking can reverse some epigenetic modifications and improve health.

A second way to look at the interplay between nutrients and genes is to identify genetic markers in individuals that may modify their need for or use of various nutrients which may influence health outcomes. This is called nutrigenetics . Genetic differences may help explain why some people achieve weight loss with certain diets and others do not. Or whether a person may benefit more from a low sodium diet than someone else might. You may see internet sites touting personalized nutrition, their ability to help you (for a hefty fee), “eat right for your genes.” Although this is an exciting area of research, the science is complicated. Be sure that if you access these services, that there is a health professional such as an RD/RDN who can help you interpret your individual results.

Because genetics play a large role in defining your health it is a good idea to learn whether there are some diseases and conditions that may be more likely to affect you based on your inherited genes. To do this, record your family’s medical history. Start by drawing a chart that lists your immediate family and relatives. The next time you attend a family event or see extended family members, start filling in the blanks. What did people die from? What country did Grandpa come from? While this may be an interesting project historically, it can also provide you with a practical tool to determine to what diseases you might be more susceptible. This will allow you to make better dietary and lifestyle changes early on to help prevent a disease from being handed down from your family to you. It is good to compile your information from multiple relatives.

Risk Factors

Assessing your current health status based on these six categories can help you identify some of your risk factors. A risk factor is something that makes you more likely to develop adverse health conditions. Some risk factors are inherited through your genes as discussed previously. These risk factors are part of your DNA, but may be affected by your health behaviors, either positively or negatively. However, scientists consider them non-modifiable because they are part of your genetic code which cannot be altered. Other risk factors such as biological sex, age, and race are also non-modifiable. Some risk factors are modifiable because they are choices an individual makes each day. For example, if you smoke you are more likely to develop lung cancer than someone who does not smoke. Thus smoking is a risk factor for lung cancer. Some people can smoke for years and never develop lung cancer, while others may develop lung cancer and never smoke. However, the chances that you will develop lung cancer if you’re a smoker are much higher than if you never smoked. If you quit smoking, you may reduce your risk of developing this terrible disease. Obesity, physical inactivity, and dietary factors such as low fiber intake and high saturated fat intake are risk factors for many different health conditions including heart disease, type 2 diabetes, and some forms of cancer. Choosing healthier meals and exercising regularly can go a long way to reducing the chances that you will develop one of these debilitating health conditions. The more risk factors you have for a health condition the more likely you are to eventually suffer from it. Assessing your health using ABCDEF allows you to identify your current risk factors and to take steps to modify those you can.

Risk Factors vs Signs or Symptoms

Many people confuse risk factors with signs or symptoms of disease, but they are different. Risk factors occur prior to development of a disease. They make you more likely to develop the disease, but not everyone with a risk factor will. You will experience signs and symptoms when you have a condition. Common signs and symptoms of type 2 diabetes, for example, include frequent urination, excessive thirst, frequent hunger, tingling in the extremities, and others. These occur during and after the development of the disease. To reiterate, risk factors occur prior to disease development. The more risk factors you have for a health condition (both modifiable and non-modifiable) the more likely you are to develop that condition. Signs and symptoms are experienced once you develop the condition.

1.3  Nutrients

As we saw in the previous section, many different factors affect our overall health and well-being. In this course our primary focus is on the role of dietary nutrient intake and nutrient functions in body processes.

Our bodies require dozens of different chemicals found in food to help us maintain optimal health. These chemicals are called nutrients , and the study of how these chemicals interact with each other and with our bodies is called nutrition . Nutrients are substances required by the body to perform its basic functions. We consume our favorite foods and beverages (and sometimes our not so favorites) in an attempt to gain all of the necessary nutrients to achieve or maintain our health. Sometimes we also consume supplements in addition to foods to be sure we are getting all of the required nutrients.

Although all nutrients are important, scientists categorize some as essential . The word essential means we have to have it, however, in nutrition the word essential also means we have to obtain it from an outside source, from foods or beverages. In other words, an essential nutrient is one we need that we have to consume. Non-essential nutrients are also necessary and vital for good health, but these nutrients can be made by the body in sufficient amounts as long as adequate essential nutrients are consumed, and don’t necessarily need to be a part of our daily dietary intake. Sometimes a formerly non-essential nutrient may become conditionally essential . This means that under normal circumstances a person could manufacture what they need, but if, for example, they are taking a certain medication or have a medical condition that modifies their ability to make the nutrient, then they must consume it.

Nutrients are used to help us produce energy, detect and respond to environmental surroundings, move, excrete wastes, respire (breathe), grow, and reproduce. To make it easier to study nutrients, we combine those that have similar properties or functions into groups or “classes.” There are six classes of nutrients required for the body to function and maintain overall health. These classes are carbohydrates, protein, lipids, water, vitamins, and minerals.

Table 1.3.1  Classes of Nutrients and their Basic Functions

Macronutrients.

Nutrients that are needed in large amounts are called macronutrients . There are four classes of macronutrients: carbohydrates, protein, lipids, and water. Of these macronutrients, three (carbohydrate, protein, and lipids) can be metabolically processed into cellular energy and thus are called energy nutrients . The energy from macronutrients comes from their chemical bonds. This chemical energy is converted into cellular energy in the form of adenosine triphosphate (ATP) that is then utilized to perform work, allowing our bodies to conduct their basic functions. Water is also a macronutrient in the sense that you require a large amount of it, but unlike the other macronutrients it does not yield calories.

A unit of measurement of food energy is the calorie (denoted with a small “c”). A calorie is the amount of energy required to raise 1 gram of water 1° Celsius. On nutrition food labels and in the field of nutrition the amount given for “Calories” is actually equivalent to each calorie multiplied by one thousand. A kilocalorie or kcal (one thousand calories, denoted with a small “c”) is synonymous with the “Calorie” (with a capital “C”). When you see Calories on nutrition food labels it is equal to kcal (Calorie = kcal). Therefore you can use “kcal” to denote amounts of energy from food (as we have done throughout this text). 

Carbohydrates

Carbohydrates are molecules composed of carbon, hydrogen, and oxygen. Any molecule that contains carbon atoms is considered an organic molecule . This use of the term organic refers only to the molecule’s chemical composition and is different from the use of the term organic in relation to how foods are grown. The main function of carbohydrates is to provide energy. The major food sources of carbohydrates are grains, milk, fruits, and starchy vegetables like potatoes. Non-starchy vegetables like broccoli or kale also contain carbohydrates, but in lesser quantities. Carbohydrates are almost exclusively found in plant-based foods. Carbohydrates are broadly classified into two forms based on their chemical structure: simple and complex.

One gram (g) of carbohydrates yields 4 kcal of energy for the cells in the body to perform work. In addition to providing energy and serving as building blocks for bigger macromolecules, carbohydrates are essential for proper functioning of the nervous system, heart, and kidneys.

All carbohydrates are made up of building blocks called monosaccharides, the most common monosaccharide is glucose. Some carbohydrates such as table sugar or honey are made of just two monosaccharides, so are called simple carbohydrates. Other carbohydrates are made up of hundreds or thousands of monosaccharides, and are called complex. Glucose can be stored for future use. In animals including humans, the storage molecule of carbohydrates is called glycogen and in plants it is known as starch . Glycogen and starches are complex carbohydrates, as is dietary fiber.

Proteins are organic molecules composed of chains of amino acids. Amino acids are simple sub-units composed of carbon, oxygen, hydrogen, and nitrogen. The food sources of proteins are meats, dairy products, seafood, and a variety of different plant-based foods, most notably soy. The word protein comes from a Greek word meaning “of primary importance,” which is an apt description of these macronutrients; they are also known colloquially as the “workhorses” of life. Proteins provide 4 kcal of energy per g; however providing energy is not protein’s most important function. Proteins provide structure to bones, muscles and skin, they make up hormones, enzymes, neurotransmitters, and molecules important in immunity, and play a role in conducting most of the chemical reactions that take place in the body. Scientists estimate that greater than 20,000 different proteins exist within the human body.

Lipids are also a family of organic molecules composed of carbon, hydrogen, and oxygen, but unlike carbohydrates, they are insoluble in water. Lipids are found predominantly in butter, oils, meats, dairy products, nuts, and seeds, and in many processed foods. The three main types of lipids are triglycerides (or triacylglycerols), phospholipids, and sterols. The main job of lipids is to store energy. Lipids provide more energy per g than carbohydrates or protein (9 kcal per g of lipids versus 4 kcal per g of carbohydrates/protein). In addition to energy storage, lipids serve as components of cell membranes, surround and protect organs, aid in temperature regulation, and regulate many other functions in the body.

There is one other nutrient that we must consume in large quantities: water. Water does not contain carbon, making it an inorganic molecule. It is composed of two hydrogen (H 2 ) and one oxygen (O) per one molecule of water. More than 60% of your total body weight is water. Without it, nothing could be transported in or out of the body, chemical reactions would not occur, organs would not be cushioned, and body temperature would fluctuate widely. On average, an adult consumes just over two liters of water per day from food and drink. According to the “rule of threes,” a generalization supported by survival experts, a person can survive three minutes without oxygen, three days without water, and three weeks without food. Since water is so critical for life’s basic processes, the amount of water input and output is supremely important. However, water does not provide any kcal. So it is considered a macronutrient, but not an energy nutrient.

Alcohol is not considered a nutrient, although it is a source of kcal. Remember that a nutrient is something that is necessary for body functioning and overall health. Alcohol does not meet that definition of a nutrient. Alcohol itself provides approximately 7 kcal for every g consumed. In addition to alcohol, many alcoholic drinks contain additional kcal from other nutrient classes—especially carbohydrates.

Micronutrients

Micronutrients are nutrients required by the body in very small amounts, but are still essential for carrying out bodily functions. Micronutrients include all the essential minerals and vitamins. There are 13 essential vitamins and 16 minerals (see Table 1.3.2 and Table 1.3.3 for a complete list and their major functions). In contrast to carbohydrates, protein, and lipids, micronutrients are not directly used for making energy and do not contain kcal, but they assist in the process of energy production as part of enzymes (i.e., coenzymes). Enzymes are proteins that catalyze chemical reactions in the body and are involved in all aspects of body functions from producing energy, to digesting nutrients, to building macromolecules. Micronutrients play many roles in the body.

The 13 vitamins are categorized as either water-soluble or fat-soluble. The water-soluble vitamins are vitamin C and all the B vitamins, which include thiamin, riboflavin, niacin, pantothenic acid, B 6 , biotin, folate and B 12 . The fat-soluble vitamins are A, D, E, and K. Vitamins are required to perform many functions in the body such as making red blood cells, synthesizing bone tissue, and playing a role in normal vision, nervous system function, and immune system function.

Vitamin deficiencies can cause severe health problems. For example, a deficiency in niacin causes a disease called pellagra, which was common in the early twentieth century in some parts of America. The common signs and symptoms of pellagra are known as the “4D’s—diarrhea, dermatitis, dementia, and death.” Until scientists found out that better diets relieved the signs and symptoms of pellagra, many people with the disease ended up in asylums awaiting death. The deficiency of other vitamins was found to cause other disorders and diseases such as scurvy (vitamin C), night blindness (vitamin A), and rickets (vitamin D).

Table 1.3.2 Vitamins and Their Major Functions

Minerals are solid inorganic substances that form crystals and are classified depending on how much of them we need. Trace (minor) minerals such as molybdenum, selenium, zinc, iron, and iodine, are only required in a few milligrams (mg) or less per day while major minerals such as calcium, magnesium, potassium, sodium, and phosphorus, are required in hundreds of mg. Like vitamins, minerals do not contain kcal. Many minerals are critical for enzyme function, others are used to maintain fluid balance, build bone tissue, synthesize hormones, transmit nerve impulses, contract and relax muscles, and protect against harmful free radicals.

Table 1.3.3 Minerals and Their Major Functions

To review, the dozens of nutrients that the body requires are grouped into six classes based on form and function. Below is a summary of the characteristics of the six nutrient classes.

Table 1.3.4  Summary of Nutrient Class Characteristics

Food energy.

As discussed previously, food energy is measured in Calories and commonly referred to as kcal. Though this is only the first chapter you have already seen the words “kcal” and “energy” used several times. In everyday life you have probably heard people talk about how many calories (kcal) they burned on the treadmill or how many calories are listed on a bag of chips. Kcal are a measure of energy. It takes quite a lot of kcal (energy) to keep us alive. Even if a person is in a coma, they still burn approximately 1000 kcal of energy every day in order for their heart to beat, their blood to circulate, their lungs to breathe, etc. We burn even more kcal when we exercise. A food’s kcal are determined by putting the food into a bomb calorimeter, heating it, and measuring the energy output (energy = heat produced). The carbohydrates, proteins, and fats we eat and drink provide these kcal for us (and alcohol as well if we choose to consume it).

Food Quality

One measurement of food quality is the amount of nutrients it contains relative to the amount of energy it provides. High quality foods are nutrient dense , meaning they contain many nutrients relative to the amount of calories they provide. A food with high nutrient density would have a large amount of various beneficial nutrients in each “bite” of that particular food. Because “bites” are different for everyone, we use common measures such as gram (g), ounce (oz), cup (c), pound (lb), liter (L), tablespoon (tbs), etc. to help us compare different foods. (See common measures used in Appendix 1). Determining nutrient density of a food is not straightforward. One must consider the nutrient profile of a food as a whole, and it can be quite subjective. However, it is generally agreed that whole fruits and vegetables, 100% whole grains, nuts, and legumes tend to have high nutrient density. Food quality is additionally associated with its taste, texture, appearance, microbial content, and how much consumers like it.

Another measure of food quality is to examine the number of kcals in a food relative to the size of each “bite.” The term used to describe this is energy density or calorie density. Foods high in fats and sugars, like fast food burgers, pizza, candy bars, etc. would be considered energy dense since they provide many calories per bite but are typically lacking several essential vitamins, minerals, and other beneficial nutrients like fiber. We can compare the energy density of different foods if we know the number of kcals and the size of a serving for each.

A third term often used to describe food quality is “ empty calorie .” Foods such as carbonated sugary soft drinks provide many calories, but very few, if any, beneficial nutrients, making the calories “empty.”

We can compare meals to examine food quality:

Let’s say we have a choice between two different breakfasts depicted in Figures 1.3.5 and 1.3.6. Each breakfast contains 500 kcal. But breakfast #2 provides many more nutrients in

those 500 kcal than do the donuts. There are several different vitamins and minerals in the two types of berries and in the spinach. These fruits and vegetable also contain fiber, and there is lean protein in the eggs.

The donuts in breakfast #1 contain 500 kcal as well, but those kcals are primarily fat and sugar. There are very few vitamins or minerals in the donuts, and almost no fiber or protein. Therefore, breakfast #2 is more nutrient dense.

We can also compare the energy density of the two breakfasts. Because we know the weights of the two (in grams) and that both contain 500 kcal, we can calculate the energy density of each breakfast.

Energy density of breakfast #1: 500 kcal/135 g = 3.7 kcal per gram of food

Energy density of breakfast #2: 500 kcal/350 g = 1.4 kcal per gram of food

Breakfast #1 has more than 2.5 times as many kcal per gram of food than breakfast #2. Therefore breakfast #1 has higher energy density.

Super Foods

Often you see lists of “Super Foods” on the internet or in magazines. These superfoods (also called “functional foods”) are generally understood to be a food, or a food ingredient, that may provide a health benefit beyond the traditional nutrients it contains. 3 These functional foods tend to be whole (not processed) vegetables and fruits like kale or Swiss chard, legumes, or berries, or animal foods like cold water fish. They are considered highly nutritious because they contain not only beneficial nutrients, but also additional beneficial chemical compound(s) that are not nutrients (also called non-nutritive).

Phytochemicals are non-nutritive chemical compounds found in plants (phyto) that provide characteristics to the plant like color, taste, smell. They are found in the edible parts of plants, especially the skin or peel. However, these plant chemicals are also believed to provide health benefits beyond the traditional nutrients. According to the Harvard Medical School, it is estimated that about 5,000 have been identified so far, but we don’t yet know what they all do. 4 General categories of phytochemicals include (but are not limited to) carotenoids, flavonoids, and phenols.

Diets rich in fruits and vegetables have been associated with decreased risk of chronic diseases. Many fruits and vegetables are rich in phytochemicals, especially when consumed whole, leading some to hypothesize that phytochemicals are responsible for the decreased risk of chronic diseases. The role that phytochemicals play in health is still in the early stages of research. But you may be able to reduce your risk of chronic disease by consuming high amounts of whole fruits and vegetables to raise your intake of these phytochemicals. However, benefits seem to only come from the plant itself, and not from dietary supplements containing the phytochemical.

1.4 Nutrition Research and the Scientific Method

Similar to the method by which a police detective finally charges a criminal with a crime, nutritional scientists discover the health effects of food and its nutrients by first making an observation. Once observations are made, they come up with a hypothesis, test their hypothesis, and then interpret the results. After this, they gather additional evidence from multiple sources and finally come up with a conclusion on whether the food suspect fits the claim. This organized process of inquiry developed in the 17th century is used in the sciences including nutritional science, and is called the scientific method .

One example of how the scientific method has been used in nutritional sciences is in the identification of the mineral iodine and it’s role in the thyroid gland. In the early 1800s the development of an enlargement of the neck, known as a goiter, was common in the population, especially in those living far from the sea. It was thought to be caused by poor hygiene. Because of the use of the scientific method, we now know that a goiter develops when iodine in the diet is deficient. Below is a description of how this was determined.

In 1811, French chemist Bernard Courtois was isolating saltpeter for producing gunpowder to be used by Napoleon’s army. To carry out this isolation he burned some seaweed and, in the process, observed an intense violet vapor that crystallized when he exposed it to a cold surface. He sent the violet crystals to an expert on gases, Joseph Gay-Lussac, who identified the crystal as a new element. It was named iodine, the Greek word for violet. The following scientific record is some of what took place in order to conclude that iodine is a nutrient using the steps of the scientific method: observation, hypothesis, experimental test, interpretation of results. 5 Repeat these steps to gather more evidence until you have enough evidence to reach a conclusion.

Steps of the Scientific Method used to identify Iodine

Observation . Eating seaweed is a cure for goiter, an enlargement of the thyroid gland in  the neck.

Hypothesis . In 1813, Swiss physician Jean-Francois Coindet hypothesized that the seaweed contains iodine and he could use just iodine instead of seaweed to treat his patients.

Experimental test . Coindet administered iodine tincture orally to his patients with goiter.

Interpret results . Coindet’s iodine treatment was successful.

Gathering more evidenc e. Many other physicians contributed to the research on iodine deficiency and goiter.

Hypothesis . French chemist Chatin proposed that the low iodine content in food and water of certain areas far away from the ocean were the primary cause of goiter and renounced the theory that goiter was the result of poor hygiene.

Experimental test . In the late 1860s the program, “The stamping-out of goiter,” started with people in several villages in France being given iodine tablets.

Results . The program was effective and 80% of children with goiter were cured.

Hypothesis . In 1918, Swiss doctor Bayard proposed iodizing salt as a good way to treat areas where much of the population suffered from goiter.

Experimental test . Iodized salt was transported by mules to a small village at the base of the Matterhorn where more than 75% of school children had goiter. It was given to families to use for six months.

Results . The iodized salt was beneficial in treating goiter in this remote population.

Experimental test . Physician David Marine conducted the first experiment of treating goiter with iodized salt in America in Akron, Ohio. 6

Results . This study conducted on over 4,000 school children found that iodized salt prevents goiter.

Conclusions . Seven other studies similar to Marine’s were conducted in Italy and Switzerland that also demonstrated the effectiveness of iodized salt in treating goiter. In 1924, US public health officials initiated the program of iodizing salt and started eliminating the scourge of goiterism. Today more than 70% of American households use iodized salt and many other countries have followed the same public health strategy to reduce the health consequences of iodine deficiency.

This is just one example of how the scientific method was used to determine how to treat a specific health condition. There have been millions of studies using this method, and you are benefitting from the results of these studies when you take a medication for a specific disease or condition, or when you modify a behavior to achieve a desired result.

Food for Thought

What are some of the ways in which you think like a scientist and use the scientific method in your everyday life? Any decision-making process uses at least pieces of the scientific method. Think about some of the major decisions you have made in your life and the research you conducted that supported your decision. For example, what computer brand do you own? What form of transportation do you use? What college do you attend?

Evidence-Based Approach to Nutrition

It took more than 100 years from iodine’s discovery as an effective treatment for goiter until public health programs recognized it as such. Although a lengthy process, the scientific method is a productive way to define essential nutrients and determine their ability to promote health and prevent disease. The scientific method is part of the overall evidence-based approach to designing nutritional guidelines. An evidence-based approach to nutrition includes 7 :

• Defining the problem or uncertainty (e.g., the rate of colon cancer is higher in people who eat red meat)
• Formulating it as a question (e.g., does eating red meat contribute to colon cancer?)
• Setting criteria for quality evidence
• Evaluating the body of evidence
• Summarizing the body of evidence and making decisions
• Specifying the strength of the supporting evidence required to make decisions
• Disseminating the findings

The Food and Nutrition Board of the National Academy of Medicine (NAM) [formerly known as  the Institute of Medicine (IOM)], a non-profit, non-governmental organization, constructs its nutrient recommendations (i.e., Dietary Reference Intakes, or DRI) using an evidence-based approach to nutrition. The entire procedure for setting the DRI is documented and made available to the public. The same approach is used by the US Department of Agriculture (USDA) and US Department of Health and Human Services (HHS). The USDA and HHS websites are great tools for discovering ways to optimize health; however, it is important to gather nutrition information from multiple resources as there are often differences in opinion among various scientists and public health organizations.

Types of Scientific Studies

There are many types of scientific studies that can be used to test a particular hypothesis including epidemiological studies, interventional clinical trials, and randomized clinical interventional trials.

Table 1.4.1  Types of Scientific Studies

Epidemiological studies observe what is actually happening in a population in relation to health over time. The goal is to find factors associated with an increased or decreased risk for a health event, though these sometimes remain elusive. Often these types of studies can help refine a hypothesis. They can be used to predict future health needs, but cannot directly determine if one variable causes another.

Interventional clinical trial studies are scientific investigations in which a variable is changed between groups of people. When well done, this type of study allows one to determine causal relationships. A randomized clinical interventional trial is a study in which participants are assigned by chance to separate groups that compare different treatments. Neither the researchers nor the participants can choose or know which group a participant is assigned to. That’s called a double blind study . In these types of studies, the control group usually receives a placebo instead of the actual intervention. These are powerful tools to provide supporting evidence for a particular relationship and are considered the “gold standard” of scientific studies.

High quality clinical interventional trial studies are:

• those that include a control group , which does not receive the intervention, to which you can compare the people who receive the intervention being tested.
• those in which the subjects are randomized into groups, meaning a given subject has an equal chance of ending up in either the control group or the intervention group. This is done to ensure that any possible confounding variables are likely to be evenly distributed between the control and the intervention groups.
• “double-blinded” studies in which neither the researchers nor the participants know into which group they have been assigned. This is done to reduce bias on the part of the researchers.
• those studies that include a sufficient number of participants (signified by “ n ”). Generally the higher the “n ” the more robust and significant is the study.

The limitations of clinical intervention studies are that they are difficult to carry on for long periods of time, are costly, and require that participants remain compliant with the intervention. Furthermore, it is unethical to study certain interventions. (An example of an unethical intervention would be to advise one group of pregnant mothers to drink alcohol to determine the effects of alcohol intake on pregnancy outcome, because we know that alcohol consumption during pregnancy damages the developing fetus.)

Because of the types of study limitations it is clear that epidemiological studies complement interventional clinical trial studies and BOTH are necessary to construct strong foundations of scientific evidence for health promotion and disease prevention.

Other scientific studies used to provide supporting evidence for a hypothesis include laboratory studies conducted on animals or cells. An advantage of this type of study is that they typically are less expensive than human studies and they require less time to conduct. Other advantages are that researchers have more control over the environment and the amount of confounding variables can be significantly reduced. Moreover, animal and cell studies provide a way to study relationships at the molecular level and are also helpful in determining the exact mechanism by which a specific nutrient causes a change in health. The main disadvantage of these types of studies is that researchers are not working with whole humans and thus the results may not be as applicable. Nevertheless, well-conducted animal and cell studies that can be repeated by multiple researchers and obtain the same conclusion are definitely helpful in building the evidence to support a scientific hypothesis.

Science is always moving forward, albeit sometimes slowly. One study is not enough to make a guideline or a recommendation or cure a disease. Science is a step-by-step, gradual process that builds on past evidence and finally culminates into a well accepted conclusion. Unfortunately, not all scientific conclusions are developed in the interest of human health and it is important to know where a scientific study was conducted and who provided the funding for the study. This can help you identify bias. Bias means that a researcher or group prefers one outcome over another, so they do not give all possible outcomes an equal chance. If you read an air quality study paid for by a tobacco company that found that smoking did not reduce indoor air quality, you would be skeptical of that result. You should also be skeptical of one on the benefits of red meat performed at a laboratory funded by a national beef association, or the benefits of a dietary supplement paid for by a supplement manufacturing corporation.

Science can also be contentious even among experts that do not have any conflicting financial interests. Contentious science is actually a good thing as it forces researchers to be of high integrity, well-educated, well-trained, and dedicated. It also instigates public health policy makers to seek out multiple sources of evidence in order to support a new policy. Agreement involving many experts across multiple scientific disciplines is necessary for recommending dietary changes to improve health and prevent disease. Although a somewhat slow process, it is better for our health to allow the evidence to accumulate before incorporating some change in our diet.

1.5  Nutrition and the Media

A motivational speaker once said, “A smart person believes half of what they read. An intelligent person knows which half to believe.” In this age of information where instant Internet access is just a click away, it is easy to be misled if you do not know where to go for reliable nutrition information. There are a few websites that can be consistently relied upon for accurate material that is updated regularly.

Using Eyes of Discernment

“New study shows that margarine contributes to arterial plaque.” “Asian study reveals that two cups of coffee per day can have detrimental effects on the nervous system.” “Stack your snacks to add three pounds of muscle.”

How do you react when you read news of this nature? Do you boycott margarine and coffee? Change your snacking habits? Nutrition-related hyperbolic headlines and advertisements have been around for decades. In the 1930s there were ads recommending a “reducing soap” that would wash away fat and years of age. In the 1950s and 60s you could reduce your weight by listening to certain music, or by rubbing an “electric spot reducer” over your abdomen. We still see similar types of advertisements on food packaging, and in print and social media. Advertisers use authority figures like actors dressed in white lab coats to convince consumers that a product is healthful. They often use anecdotal evidence (stories) like before and after pictures or warped statistics or single research studies that may contain bias to exaggerate the benefits of a weight loss plan, “health” food, or dietary supplement. But this type of advertising and these sorts of headlines seem to work. Consumers spend billions of dollars each year on special health foods and beverages or dietary supplements even though the scientific evidence that these substances live up to their hype is sorely lacking.

So what should we as consumers believe?  When reading nutrition-related claims, articles, websites, or advertisements always remember that one study does not substantiate a fact. One study neither proves or disproves anything. Readers who may be looking for complex answers to nutritional dilemmas can quickly misconstrue such statements and be led down a path of misinformation. Listed below are ways that you can develop discerning eyes when reading nutritional news.

• The scientific study under discussion should be published in a peer-reviewed journal, such as the Journal of the Academy of Nutrition and Dietetics. Question studies that come from less trustworthy sources (such as non peer-reviewed journals, popular magazines, or websites) or that are not published.
• The report should disclose the methods used by the researcher(s). Did the study last for 3 or 30 weeks? What was the “ n ” (number of subjects)? The longer the study and the higher the number of subjects, the more robust and credible are the results. What did the participants actually do? Did the researcher(s) observe the results themselves or did they rely on self reports from study participants? Was there a control group who did not receive the treatment so that scientists can compare one group to another?
• Who were the subjects of this study? Humans or animals? If human, are any traits/characteristics noted? Were confounding variables assessed? How were subjects assigned to groups (randomness)? For example, the results of a study of the effects of a dietary supplement on the hearts of cardiac patients should not be used to convince an athlete to take a dietary supplement to improve their own heart’s ability to exercise. These two types of people are quite different. You may realize you have more in common with certain program participants and can use that as a basis to gauge if the study applies to you (age, biological sex, fitness level, underlying medical conditions, geographical location, etc.)
• Credible reports often disseminate new findings in the context of previous research. A single study on its own gives you very limited information, but if a body of literature supports a finding, it gives you more confidence in it.
• Peer-reviewed articles published in well-respected scientific journals deliver a broad perspective and are inclusive of findings of many studies on the exact same subject. By providing a list of previously published articles related to the topic, one can see how a particular study fits into the totality of the research.
• When reading news, ask yourself, “Is this making sense?” Even if coffee does adversely affect the nervous system, do you drink enough of it to see any negative effects? Remember, if a headline professes a new remedy for a nutrition-related topic, it may well be a research-supported piece of news, but more often than not it is a sensational story designed to catch the attention of an unsuspecting consumer. Track down the original journal article to see if it really supports the conclusions being drawn in the news report.

There are thousands of websites that contain nutrition information. When reading information on websites, Johns Hopkins University recommends that you remember the following criteria for discerning if a site is valid and the information credible 8:

Accuracy. Does the website use reliable research? Check many sources for the same information—are the results the same?

Authority. Websites that end in .gov or .edu (and sometimes .org), are usually the most reliable websites for health facts. Make sure the website is written by doctors, dietitians, or other experts in the health field.

Bias. Who pays for the website? If a company supports a website (usually through advertising) they may have control over the website and encourage inaccurate or misleading information that promotes a need for their product or service.

Currency. When were the facts last updated? Medical research never stops. Make sure the information is no older than 3 years.

Some non-profit, non-governmental organizations like Health on the Net (HON), affiliated with the WHO, promote transparency and reliable health information on the internet. For a fee, health-related websites can have their content checked by medical experts from these organizations for accuracy and reliability. If a website becomes certified, it will be allowed to post the organization’s logo on their site for a specified time period (usually 5 years). 9 Other organizations like the Utilization Review Accreditation Commission (URAC) have a Health Website accreditation program that looks at both content and security settings for these sites. While these certifications do not guarantee that everything on the website is accurate or reliable, it does provide some level of assurance that the information has some validity. 10

Trustworthy Sources

For a list of reliable sources that advocate good nutrition to promote health and prevent disease using evidence-based science see Table 1.5.1. In Chapter 2, we will further discuss nutrition recommendations for Americans.

Table 1.5.1 Web Resources for Nutrition and Health

Key takeaways.

• The World Health Organizations defines health as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.”
• Disease is defined as any abnormal condition that affects the health of an organism, and is characterized by specific signs and symptoms.
• Good nutrition provides a mechanism to promote health and prevent disease.
• Assessing your nutritional health using the ABCDEF characteristics can help identify risk factors for disease and encourage changes that could lead to improved health
• Nutrients are essential for our bodies to function.
• Nutrients are classified based on the amounts required for proper body functioning.  Macronutrients (carbohydrates, lipids, protein, water) are needed in relatively large amounts, and micronutrients (vitamins and minerals) are needed in very small amounts.
• Food and/or meal quality can be measured based on its nutrient density and its energy density.
• The scientific method is an organized process of inquiry used in nutritional science to determine if the food suspect fits the claim and is part of the overall evidence-based approach to designing nutritional guidelines that are based on facts.
• There are different types of scientific studies—epidemiological studies, randomized clinical interventional trial studies, and laboratory animal and cell studies—which all provide different, complementary lines of evidence.
• It takes time to build scientific evidence that culminates as a commonly accepted conclusion.
• Reliable nutritional news will be based upon solid scientific evidence, supported by multiple studies, and published in peer-reviewed journals.

Portions of this chapter were taken from OER Sources listed below:

Tharalson, J. (2019). Nutri300:Nutrition. https://med.libretexts.org/Courses/Sacremento_City_College/SSC%3A_Nutri_300_(Tharalson) 

Titchenal, A., Calabrese, A., Gibby, C., Revilla, M.K.F., 7 Meinke, W. (2018). Human Nutrition. University of Hawai’i at Manoa Food Science and Human Nutrition Program Open Textbook. https://pressbooks.oer.hawaii.edu

Zimmerman, M., & Snow, B. (2012). An Introduction to Nutrition, v. 1.0. https://2012books.lardbucket.org/books/an-introduction-to-nutrition/

Additional References:

• World Health Organization. (1946). Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference. Official Records of the World Health Organization. https://www.who.int/about/who-we-are/constitution
• Xu, J., Murphy, S. L., Kochanek, K. D., & Arias, E. (2020). Mortality in the United States, 2018. National Center for Health Statistics. Data brief, no 355. https://www.cdc.gov/nchs/products/databriefs/db355.htm
• Klemm, S. (2019, July 15). Functional foods. Academy of Nutrition and Dietetics. https://www.eatright.org/food/nutrition/healthy-eating/functional-foods
• Harvard Health Letter. (2019, February). Fill up on phytochemicals. Harvard Medical School. https://www.health.harvard.edu/staying-healthy/fill-up-on-phytochemicals
• Zimmerman, M. B. (2008). Research on iodine deficiency and goiter in the 19th and early 20th centuries. The Journal of Nutrition, 138(11), 2060-63. doi:10.1093/jn/138.11.2060
• Carpenter, K. J. (2005). David Marine and the problem of goiter. The Journal of Nutrition, 135(4), 675-80. https://doi:10.1093/jn/135.4.675
• Briss, P.A., Zaza, S., Pappaioanou, M., Fielding, J., Wright-De Agüero, L., Truman, B. I., Hopkins, D, P., Mullen, P. D., Thompson, R. S., Woolf, S. H., Carande-Kulis, V. G., Anderson, L., Hinman, A. R., McQueen, D. V., Teutsch, S. M., & Harris, J. R. (2000). Developing an evidence-based guide to community preventive services-Methods. American Journal of Preventive Medicine, 18(1S), 35-43. https://doi:10.1016/s0749-3797(99)00119-1
• Johns Hopkins University. (2018). Reliable health information on the internet.   https://www.hopkinsmedicine.org/johns_hopkins_bayview/_docs/patient_visitor_amenities/libraries/reliable_health_information_fall_2018.pdf
• Health on the Net. (2020, March). https://www.hon.ch/en/
• Utilization Review Accreditation Commission. (2020). Health website accreditation. https://www.urac.org/programs/health-web-site-accreditation

Media Attributions

• Figure 1.3.1 macros
• 011F2C6A-1E59-46BE-8287-A0DF9E333FF5
• 0B943CEF-DB22-4B4F-BFF9-5BB9CF7F8BDD

study of how nutrients interact with each other and with the body

Scientific exploration of how an organism nourishes itself and how this nourishment affects personal, population, and planetary health.

encompasses physical, psychological, and social well-being, not just the absence of disease

any abnormal condition affecting the health of organisms, characterized by specific signs and symptoms

systematic process of collecting and interpreting information in order to make decisions about the nature and cause of nutrition-related health issues that affect an individual

things that can be easily seen such as bleeding, vomiting or fainting

things that cannot be easily seen and are usually reported by a patient such as headache, dizziness, pain, or nausea

deficiency of a nutrient caused by inadequate intake

nutrient deficiency that occurs when a person consumes an adequate amount of a nutrient, but for some reason the body cannot use what is consumed

sequence of DNA that makes up your genes

study of the relationships among genes, diet, and health outcomes

Identification of genetic markers in genes that modify the need for or use of various nutrients.

characteristic that increases the risk of developing a disease

chemicals found in food essential for health

required by the body, and it must be consumed in the diet

nutrients that can be manufactured by the body in adequate amounts so consumption is not required

a normally non-essential nutrient that becomes essential due to a disease, condition, or medication

Classes of nutrients needed in relatively large amounts. These include carbohydrate, protein, lipid, and water.

macronutrients that can provide energy in the form of kilocalories (kcal)

chemical energy obtained from the breakdown of food molecules and released to fuel cellular processes

unit of measurement of food energy; the amount of energy required to raise 1 kilogram of water 1 degree Celsius.

one thousand calories, denoted as kcal or Calorie (capital C) on nutrition food labels

term used in chemistry to denote that a molecule contains the carbon atom

main form of carbohydrate in the body

stored form of glucose in animals including humans; stored in liver and skeletal muscle

stored form of carbohydrate in plants

building blocks of protein

Lipid transport molecule surrounded by bile salts allowing dietary lipids to be absorbed into the walls of the small intestine

Food or beverages such as sugary sodas or candy containing calories but no beneficial nutrients

a system by which a hypothesis is developed based on observation, then the hypothesis is tested and modified based on the outcome of tests and experiments

types of scientific studies that observe what happens in a population in relation to health over time in order to find risk factors for a health event; these types of studies do not determine cause

studies that change one variable between groups to determine causal relationships

type of study where participants are assigned by chance to a particular group that compares different treatments

a type of research study design in which neither the participant nor the researcher know in which group (treatment or control) the participant is assigned; It is a way to minimize bias

a substance that has no therapeutic effect

group in a research study that does not receive any type of treatment

letter used in research studies to indicate the number of participants in the study; ex. n=150 means there are 150 participants in the study. Generally the higher the n the more credible the results of the study

factors other than the ones being tested in a research study that could be influencing the results. It is important to control for as many variables as possible to assure research results are valid

Consumer Nutrition Copyright © 2021 by Megan Grimsley and Susan Kazen is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Artificial intelligence in nutrition research: perspectives on current and future applications

Affiliations.

• 1 Centre de recherche Nutrition, santé et société (NUTRISS), INAF, Université Laval, Québec, QC, Canada.
• 2 School of Nutrition, Université Laval, Québec, QC, Canada.
• PMID: 34525321
• DOI: 10.1139/apnm-2021-0448

Artificial intelligence (AI) is a rapidly evolving area that offers unparalleled opportunities of progress and applications in many healthcare fields. In this review, we provide an overview of the main and latest applications of AI in nutrition research and identify gaps to address to potentialize this emerging field. AI algorithms may help better understand and predict the complex and non-linear interactions between nutrition-related data and health outcomes, particularly when large amounts of data need to be structured and integrated, such as in metabolomics. AI-based approaches, including image recognition, may also improve dietary assessment by maximizing efficiency and addressing systematic and random errors associated with self-reported measurements of dietary intakes. Finally, AI applications can extract, structure and analyze large amounts of data from social media platforms to better understand dietary behaviours and perceptions among the population. In summary, AI-based approaches will likely improve and advance nutrition research as well as help explore new applications. However, further research is needed to identify areas where AI does deliver added value compared with traditional approaches, and other areas where AI is simply not likely to advance the field. Novelty: Artificial intelligence offers unparalleled opportunities of progress and applications in nutrition. There remain gaps to address to potentialize this emerging field.

Keywords: algorithmes; algorithms; apprentissage automatique; artificial intelligence; dietary assessment; intelligence artificielle; machine learning; metabolomics; médias sociaux; métabolomique; nutrition; prediction; prédiction; social media; évaluation alimentaire.

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1 Introduction to nutrition

• Published: April 2020
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Breakfast in Human Nutrition: The International Breakfast Research Initiative

Michael j. gibney.

1 Institute of Food and Health, University College Dublin, Dublin D04 V1W8, Ireland

Susan I. Barr

2 Department of Food, Nutrition & Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; [email protected]

France Bellisle

3 Nutri Psy Consult, 91 rue de la Sante, 75013 Paris, France; rf.31sirap-vinu.hbms.neru@elsilleb

Adam Drewnowski

4 Center for Public Health Nutrition, University of Washington, Seattle, WA 98195-3410, USA; ude.wu@werdmada

5 Division for Risk Assessment and Nutrition, The National Food Institute, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark; kd.utd.doof@afsis

Barbara Livingstone

6 Nutrition Innovation Centre for Food and Health, Ulster University, Coleraine BT52 1SA, UK; [email protected]

Gabriel Masset

7 Cereal Partners Worldwide, CH-1350 Orbe, Switzerland; moc.eltsen@agtessamdr (G.M.); [email protected] (S.H.)

Gregorio Varela Moreiras

8 Department of Pharmaceutical and Health Sciences, Faculty of Pharmacy, CEU San Pablo University, 28668 Madrid, Spain; se.uec@aleravg

Luis A. Moreno

9 GENUD (Growth, Exercise, Nutrition and Development) Research Group, Universidad de Zaragoza, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Instituto Agroalimentario de Aragón (IA2), Centro de Investigación Biomédica en red Fisiopatología de la Obesidad y Nutrición (CIBEROBN), 50009 Zaragoza, Spain; se.razinu@oneroml

Jessica Smith

10 Bell Institute of Health, Nutrition and Food Safety, General Mills, Minneapolis, MN 55427-3870, USA; [email protected]

Florent Vieux

11 MS-Nutrition, 13385 Marseille cedex 5, France; [email protected]

Frank Thielecke

12 Thielecke Consultancy, CH-4123 Allschwil, Switzerland; [email protected]

Sinead Hopkins

Breakfast is often referred to as the most important meal of the day and in recent years has been implicated in weight control, cardio-metabolic risk factors and cognitive performance although, at present, the literature remains inconclusive as to the precise health benefits of breakfast. There are extensive reports of breakfast’s contributions to daily food and nutrient intakes, as well as many studies that have compared daily food and nutrient intakes by breakfast consumers and skippers. However, significant variation exists in the definitions of breakfast and breakfast skippers, and in methods used to relate breakfast nutrient intakes to overall diet quality. The present review describes a novel and harmonised approach to the study of the nutritional impact of breakfast through The International Breakfast research Initiative involving national dietary survey data from Canada, Denmark, France, Spain, the UK and the USA. It is anticipated that the analysis of such data along harmonised lines, will allow the project to achieve its primary goal of exploring approaches to defining optimal breakfast food and nutrient intakes. Such data will be of value to public health nutrition policy-makers and food manufacturers and will also allow consistent messaging to help consumers to optimize food choices at breakfast.

1. Introduction

At different times throughout history, those who shape policy have had varying beliefs about the importance of breakfast in overall diet quality. Today, there would appear to be universal recognition that breakfast should play a significant role in helping consumers attain an optimal nutritional profile. There is a wealth of data on the patterns of breakfast intake from national dietary surveys, on the foods commonly consumed at breakfast, their contribution to breakfast intake and on the role of breakfast in meeting overall daily nutrient targets. Notwithstanding the scale of this literature, significant challenges exist given the variation in such basic concepts as defining breakfast or breakfast skippers as well as exploring how breakfast food and nutrient intakes might be related to overall dietary quality. The International Breakfast Research Initiative (IBRI) was established to provide a cross country harmonised analysis of national and large regional food consumption databases to provide a clearer picture of food and nutrient intakes at breakfast. The international collaborative project represents a broad range of expertise from Europe and North America, including behavioral, public health and nutrition scientists from academia and industry. Data from the US, Canada, the UK, Denmark, Spain and France will be used, and it is expected that the provision of such data might permit a more learned approach to defining nutritional quality standards for breakfast. This will involve the development of novel concepts of defining dietary guidelines pertaining to a specific meal, breakfast, rather than to the overall daily food pattern and will facilitate the development of nutritional standards for breakfast by national and international agencies. This will also help to provide clear guidelines to food manufacturers for developing healthy breakfast options and will ultimately benefit consumers in making decisions about breakfast food choices.

2. Breakfast: A Brief History

From a physiological perspective, breakfast is unique among our meals in that it is eaten after the longest of our postprandial fasts, in this instance an overnight fast. In his book, A History of Breakfast, Andersen describes some of the features of breakfast in the human diet over centuries. [ 1 ] From the gastronomic perspective, breakfast was traditionally, dating back to Greek and Roman breakfasts (ariston and Ientaculum respectively), the least demanding of our meals in culinary terms in that it consisted for centuries as a simple meal of bread, cheese, honey, oil and maybe wine. Thus, it was from the very early times, a meal characterised by convenience since none of these ingredients required preparation or further cooking. Convenience was important for early risers who had to attend crops and livestock and it was also important for those who had to travel distances after rising. In general, breakfast was seen in the earliest days of recorded history and up to the middle ages as a meal for infants and the infirm, but it was acceptable for the labouring classes. By the 16th century, Europeans began to see breakfast as an important meal in terms of overall health. Thomas Cogan, an English school master in Manchester, in describing the skipping of breakfast, argued that to “suffer hunger long filleth the stomach with ill humours”. Whilst breakfast meant simple foods for the masses, including gruels based on oats, rice and other cereals, the rich and ennobled began to include eggs and meat as a component of breakfast. “This “cooked breakfast”, which was widely adopted in the US, was targeted by the Clean-Living Movement. This Movement primarily advocated against alcohol, tobacco and birth control, but also made dietary recommendations: avoiding meat and coffee, using filtered water, and increasing intake of whole grain foods [ 2 ]. Against this background, the Seventh Day Adventists John Harvey Kellogg developed the flaked breakfast cereal in 1894 and in 1945, the Kellogg Company first introduced the cereal box that we know today. At any point in history, the timing and nature of breakfast has varied widely both geographically and socially and to this day, that variability prevails. Of considerable interest in present context is the development of shift work and attendant night work. For the majority of countries for which data are available, about 20% of employees are engaged in night [ 3 ].

3. Existing Recommendations on Breakfast Consumption

It is frequently stated that breakfast is a very important meal and that it deserves special attention, especially among children and this is borne out by published opinions of international agencies, national governments and non-governmental organisations. One of the most wide-reaching reports is that of the European branch of the World Health Organisation, who conducted a health behaviour survey of over 200,000 male and female schoolchildren, 11–13 and 15 years of age in 39 European states in 2009/2010 [ 4 ]. Overall, 61% of 13 year olds consumed a breakfast on each school day while the figure fell to 55% among 15 year olds. In general, breakfast consumption was most common among boys and declined with lower socio-economic status. These data show that about half to one third of children don’t have breakfast every day, although the data does not reveal the actual frequency of breakfast intake. The report notes that regular breakfast consumption is associated with higher intakes of micronutrients, a better diet that includes fruit and vegetables and less frequent use of soft drinks. The report concludes that establishing the most effective programmes and policies to promote breakfast intake across countries is a public health challenge.

The American Heart Association issued a scientific opinion in 2017 on “Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention” [ 5 ]. As regards breakfast and nutrient balance they cite a cross-sectional survey of the Bogalusa Heart Study ( n = 504; 58% women; 70% white; mean age, 23 years [range, 19–28 years]) which demonstrated that 74% of breakfast skippers did not meet two thirds of the Recommended Dietary Allowance for vitamins and minerals compared with 41% of those who consumed breakfast. They also cite US data showing that young adults (age, 20–39 years) who reported skipping breakfast had overall daily diets that were less than optimal in terms of nutrient intake as measured by indices of total daily diet quality (Mean Adequacy Ratio, MAR and Healthy Eating Index HEI) [ 6 , 7 ]. Taking into account the direct evidence linking breakfast intake both to overall dietary patterns and the presence of cardio-metabolic risk factors, the statement concludes: “On the basis of the combined epidemiological and clinical intervention data, daily breakfast consumption among US adults may decrease the risk of adverse effects related to glucose and insulin metabolism. In addition, comprehensive dietary counselling that supports daily breakfast consumption may be helpful in promoting healthy dietary habits throughout the day”.

Most institutes of nutrition and dietetics recommend eating a healthy breakfast as an integral component of a nutritionally optimal diet such as in the US, UK and Australia among many [ 8 , 9 , 10 ]. Individual governments have issued dietary advice promoting breakfast [ 8 ]. Where specific advice exists advocating a healthy breakfast, it is usually focussed on food group choice, which is not normally based on data derived from the analysis of national dietary surveys [ 11 , 12 , 13 ]. In some countries such as the US and Mexico, detailed policy guidelines exist for both food and nutrient intake for school breakfasts [ 14 , 15 ]. However, in both cases, the nutritional guidelines are (a) adapted from the general dietary guidelines for the population which are then applied to children’s recommended energy intakes; (b) do not relate the food-based advice to any nutritional origins and (c) fail to provide any detailed examination of the role of micronutrients in breakfast other than a bland recommendation that their intake should meet 20% of the RDA. In addition, several breakfast quality indexes have been proposed at national level [ 16 , 17 , 18 ]. These usually follow very closely diet guidelines by focusing on food groups and some nutrients, without taking into account actual intakes at breakfast.

4. Breakfast as a Source of Daily Nutrients

There is a very extensive literature on nutrient intake at breakfast and the extent to which breakfast-based nutrients contribute to overall daily nutrient intake. The vast majority of such studies show a clear overall nutritional benefit of consuming breakfast in respect of the key nutrients of public health importance in many countries. This section seeks to select a few large nationally representative studies in this field to illustrate the impact of breakfast on overall daily nutrient intake.

Australia (2017): Data were obtained from the 2011–2012 National Nutrition and Physical Activity Survey which used a 24-h recall method in a sample of 12,153 subjects. Breakfast patterns were studied in 2821 children and adolescents aged 2 to 18 years of age [ 19 ]. Some 9% of the sample were classified as breakfast skippers while the remainder were equally divided between those consuming cereal-based breakfasts (45%) or other breakfast types (46%). Among breakfast skippers, 61% were in the 14–18 year old age group. Breakfast skippers had higher intakes of saturated fatty acids and lower intakes of dietary fibre and most micronutrients. Among breakfast consumers, those consuming breakfast cereals had higher intakes of total sugars but not of either free and added sugars and also had higher intakes of dietary fibre. They had lower intakes of total fat and sodium. Generally, they had higher intakes of most micronutrients.

Brazil (2017) : The data used were from the Brazilian National Dietary Survey of 2008–2009 used two 24-h recalls [ 20 ]. The total sample surveyed was 34,003 and the data reported on breakfast intakes were for 7276 children and adolescents aged 10–19 years. Breakfast skippers accounted for 7% of the population while occasional and regular breakfast consumers represented 12% and 81% respectively. The mean daily intakes of total energy, sugar, and calcium were higher among occasional consumers and skippers. Breakfast consumers had higher intake of vitamins B 12 , C, and D. Breakfast consumers had lower total and added sugar intakes and lower calcium intakes compared to occasional consumers and skippers.

Canada (2004): Data from the nationally-representative Canadian Community Health Survey of 2004 were used to study the contribution of breakfast to daily nutrient intake and the prevalence of nutrient inadequacy (% with intakes < EAR) of Canadian children (aged 4–18 year; n = 12,281) and adults (aged 19+ year; n = 19,913) [ 21 , 22 ]. Data were collected using multiple-pass 24-h recalls. Overall, 10% of children and 11% of adults were breakfast non-consumers, 33% of children and 23% of adults consumed breakfasts containing ready-to-eat cereal (RTEC), and 57% of children and 66% of adults consumed other breakfasts. Breakfast non-consumers had lower energy intakes than breakfast consumers; accordingly, reported nutrient intakes were energy-adjusted. Breakfast consumers, and to a greater extent, consumers of RTEC breakfasts, had higher intakes of fibre, several vitamins and minerals, and among children, lower intakes of fat. Among both adults and children, the prevalence of nutrient inadequacy (intakes < EAR) for vitamins A and D, calcium, iron and magnesium were significantly higher among breakfast non-consumers than RTEC breakfast consumers; among children, this was also the case for vitamin B6, folate and zinc. The prevalence of inadequacy among consumers of other breakfasts generally fell in between the other two groups.

Korea (2009): The sample of this study consisted of 1600 children aged 7–18 years attending elementary, middle, or high schools and who participated in the 2001 National Health and Nutrition Survey [ 23 ]. A 24 h-record was used to estimate dietary habits. The sample was divided into 4 groups: breakfast skippers and three levels of breakfast intake based on % contribution of breakfast to estimates of energy requirements (EER): low (<10% EER), moderate (10–25% EER) or sufficient (>25% EER). The percentages consuming daily diet with protein, vitamin A, B1, B2, niacin, vitamin C, calcium, phosphorus, or iron less than Estimated Average Requirement decreased in the breakfast groups as %EER increased. Similarly, a Dietary Variety Score which measures overall daily food variety rose with greater contribution of breakfast to daily energy intake.

USA (2018): Food and nutrient intakes were evaluated in a sample of children aged 2–5 years (3443) and 6–12 years (5167) from the NHANES 2005–2012 survey [ 24 ]. Diet quality was assessed for breakfast skippers and consumers. Snacks, sweets, beverages (non-dairy, non-alcoholic) and mixed dishes were higher in contribution to daily energy intake among skippers as compared to consumers. Grains and milk products contributed more to total daily energy intake among breakfast consumers. Breakfast eaters consumed lower overall daily levels of added sugar and higher levels of fibre, folate, iron, vitamin C, vitamin A and calcium. For both age groups, the Healthy Eating Index was higher among breakfast consumers compared to non-consumers. Across all meals (breakfast, lunch, dinner, and snacks) intakes of total and saturated fats were lowest at breakfast while those of folate and vitamin A were highest. Some minor differences existed in this regard across the two age groups.

UK (2017): Data are available from the UK National Diet and Nutrition Survey Rolling Programme on breakfast intakes and nutrient patterns in 1686 children and adolescents (11–18 years) using a 4-day diary [ 25 ]. Comparisons were made for those never recording a breakfast intake (17%), those consuming breakfast on 1–3 days of study (52%) and those eating breakfast every day (31%). Breakfast consumption was generally associated with higher energy intakes and in turn, with higher intakes of folic and ascorbic acids, fibre, calcium, iron and iodine intakes and lower intakes of total carbohydrates and sodium. Intakes of non-milk extrinsic sugars were lower among daily breakfast consumers compared to non-consumers if breakfast. In general, these absolute differences were sustained when adjusted for energy intake.

The data, illustrative of a large literature on the subject show the importance of breakfast intake in shaping overall optimal nutrient intake. There tends to be an emphasis on comparing breakfast skippers with breakfast consumers and within breakfast consumers to make limited comparisons of nutrient intake consequent to the nature of breakfasts consumed. Thus, in the studies included in the present international project, attempts are made to provide as harmonised an approach as possible to studying the association of breakfast consumption and breakfast skipping on overall nutrient intake. Thus, there is a common focus on nutrients and a common approach to relate breakfast nutrient intake data to the overall diet quality the Nutrient Rich Foods (NRF) index as a measure of overall dietary quality [ 26 ] In addition, diet modelling with linear programming will be used to further examine the potential role of breakfast in a nutritionally adequate diet.

Finally, several important factors often not considered in the literature such as energy under-reporting, nutritional supplement use and the use of overall diet quality indices to ascertain the true impact of breakfast on overall nutrient intake are considered in more detail in a later section of this review.

5. Food Intake Patterns among Breakfast Consumers

The many studies on the contribution of breakfast to mean daily nutrient intakes also provide data on the main foods consumed at breakfast and their contribution to nutrient intakes both at the level of breakfast and the overall daily nutrient intake. Comparisons across studies are difficult for many reasons. The exact definition of given food categories varies very considerably across studies. A category “regular breads and rolls” maybe used in one study, whereas others might use terms such as “whole grain bread”, “white bread” or “other breads”. Moreover, food intakes may be given in quantitative terms such as intakes in grams at breakfast or for the total day. Similarly, food contributions to breakfast or total daily energy intake may be expressed as a % of total or breakfast energy intake. The following again are examples of the type of food intake data that can be derived using different forms of data analysis and different end points of the impact of food intake patterns at breakfast.

France (2016): A study of 529 children aged 9–11 in the city of Rennes was used with cluster analysis to identify breakfast patterns in French children [ 27 ]. Four breakfast patterns were identified: Sweets breakfast (40%), traditional French breakfast (27%), ready-to-eat cereal with milk (18%) and dairy and juice breakfast (10%). The overall quality of breakfasts was determined using the mean adequacy ratio (MAR). The cereal-based breakfast had the highest overall MAR score at 30.2% which fell to 25% for the sweet breakfast, 23% for the traditional French breakfast and to 18% for the dairy and juice breakfast.

Germany (2017): From a sample of 1447 subjects randomly chosen from the EPIC Potsdam cohort, 815 agreed to participate in providing 2, 24-h dietary recalls of which 664 completed the study [ 28 ]. A Breakfast Quality Index (BQI) and a Daily Intake Quality Score (DQS) were calculated based on a healthy Eating Index categorisation of foods. Using data on blood lipids, HbA1c and C-reactive protein, a biomarker score (B Score) was calculated. The BQI value was more highly correlated with B Score indicating that the more nutritionally balanced the breakfast was, the more likely an individual was to have a favourable cardio-metabolic profile. The dietary data were subject to principal component analysis (PCA) to establish general patterns of food choice for both breakfasts and the total day. Only one of the breakfast patterns, that of ‘dairy and cereal’ pattern, was positively related to a favourable B Score. As regards daily patterns, only that PCA group classified as the ‘prudent diet pattern’ was indicative of a favourable cardio-metabolic profile.

Mexico (2017): Cluster analysis of the Mexican National Food Consumption Survey with data from 3760 children. These data revealed 6 dietary patterns: breakfast skippers (17%), sweetened beverages (10%), sandwiches and quesadillas (9%), eggs (8%), tortillas and beans (12%), cereal and milk (6%) and milk and sweetened breads (38%) [ 29 ]. There was little evidence of any major role for socio-economic factors in determining breakfast choices. Each breakfast choice had its own strength or weakness. For example, the highest added sugars came from the ‘sweetened beverage’ group while the highest intake of fibre came from the ‘tortillas & beans’ group. However, when total daily nutrient intakes were considered, the ‘sweetened beverage’ group’s added sugar intake did not differ significantly from all other breakfast patterns, including those who skipped breakfast. In contrast, the higher fibre intakes at breakfast were reflected in an overall higher daily fibre intake. None of the breakfast groups complied with the Mexican Breakfast School Guidelines.

United States: The 1994–1996 Continuing Survey of Food Intake by individuals involved about 23,700 individuals of which 15,641 adults aged 18–65 were selected for the breakfast analysis [ 30 ]. The methodology uses was a 24-h recall. Eggs, cereal, toast, fruit or fruit juices, coffee, and soft drinks were identified as ‘lead’ foods around which breakfast choices were made. Breakfast skipping was also recorded. The categories identified were: (1) eggs plus any other primary food group (13.3% of total breakfasts); (2) cereal plus groups not including eggs (16.8%); bread alone (19.2%); cooked cereal (3.0%); fruit (5.1%); coffee and high fat dessert (15.1%); miscellaneous (4.5%); no breakfast (23.0%). The cereal group and the fruit group had the best nutritional profile in terms of total and saturated fats, fibre and carbohydrate. Cereals however, scored highest for calcium, folate and iron intakes. Socio-economic differences in patterns of breakfast intake were notable. For example, as either income or educational status rose, egg-based breakfasts declined, and cereal based breakfasts rose.

A clear understanding of the contribution of different foods to overall nutrient intake will be essential in attempting to develop locally based guidelines on food choice for an optimal breakfast. That analysis can be confined to the mean derived from all meal choices for breakfasts. In some cases, it can be studied in greater depth if breakfast food choice is broken down into patterns of food choice for breakfast meals through principal component or cluster analysis. Another alternative might be an overall nutritional score for each subject allowing tertiles or quartiles of such an index to be related back to any aspect of breakfast nutrition: nutrient intake, food choices or meal patterns.

6. Breakfast and Health Outcomes

At present, a significant proportion of the literature on the benefits of breakfast is focused on health outcomes rather than dietary outcomes, although the two are frequently linked. The main thrust of the present consortium is to develop a greater understanding of the food and nutrient intakes at breakfast and their contribution to overall diet quality across many geographic regions rather than any impact of breakfast on health outcomes. Nonetheless, it is valuable to record some of the main directions that research in this area is making.

Several large prospective studies support the association between breakfast consumption and lower risk of obesity and weight gain [ 31 , 32 ]. Some intervention studies have challenged the importance of breakfast skipping in weight management and other scientific commentaries have cast a more critical view of the overall research approach to this area [ 33 , 34 ]. Support for the association between skipping breakfast and impaired glucose metabolism comes from four prospective studies that link skipping breakfast with a greater risk of type-2 diabetes: The Health Professionals Follow-Up Study, The Nurses’ Health Study, a Japanese study and the German EPIC cohort [ 28 , 35 , 36 , 37 ] provide evidence that regular healthy breakfast consumption is associated with improved glycemic control. Several cross-sectional studies reported an inverse association between breakfast consumption and risk factors of cardiovascular disease [ 28 ]. A prospective study of US Health Professionals documented an increase in incidence of CVD amongst those North American men who regularly failed to eat breakfast [ 38 ]. Similarly, a study, conducted in Japan showed that infrequent breakfast intake was associated with an increased risk for total CVD, total stroke, and for cerebral haemorrhage [ 39 ]. However, it was not associated with greater risk of subarachnoid haemorrhage, cerebral infarction, or coronary heart disease in this population. Data from a Spanish cohort PESA (Progression of Early Subclinical Atherosclerosis) further supports the suggestion that skipping breakfast is associated with increased odds of prevalent non-coronary and generalized atherosclerosis independently of the presence of conventional cardiovascular risk factors [ 40 ]. Taken together, data from prospective studies support consistent and strong cross-sectional evidence suggesting that breakfast consumption is associated with a reduction of cardio metabolic risk factors.

Breakfast intake is frequently related to mental alertness. Much of the research in breakfast and its potential effects on improving cognitive performance has been conducted in children and adolescents. A recent meta-analysis examined the literature on breakfast consumption versus breakfast skipping and also the nutritional composition of consumed breakfasts [ 41 ]. The studies included ( n = 45) were a mix of acute and chronic breakfast intake. Whilst there was evidence to support improved cognitive function, particularly short-term benefits on attention, executive function, and memory (more pronounced in undernourished children), the authors concluded that there were insufficient studies to draw any firm conclusions. Similarly, a review in adults that included 38 studies reported small effects on memory, but emphasized that strong conclusions are hampered by methodological disparity.

7. Challenges in Studying Breakfast Consumption

Notwithstanding the proposed importance of a good breakfast in determining overall nutritional quality, there are major gaps and assumptions in our knowledge base on breakfasts and agreement on certain definitions and research approaches may help to resolve these difficulties. This section outlines the main areas where variations in approaches and understandings may impinge upon how data are gathered, presented and, above all, interpreted.

In the course of this collaborative study, it has become clear that whilst an agreed definition of breakfast is attractive, the reality is that dietary survey methodologies vary quite considerably in how data is collected, such that a universal definition of breakfast becomes impossible. One major US review of the role of breakfast in the overall determination of diet quality, proposed a definition built around the foods consumed as the first meal of the day. The specific definition proposed was: “ Breakfast is the first meal of the day that breaks the fast after the longest period of sleep and is consumed within 2 to 3 h of waking; it is comprised of food or beverage from at least one food group and may be consumed at any location ” [ 42 ]. This consensus was reached based on an extensive review of breakfast definitions used in the literature and drew on 8 definitions as proposed in 14 published studies. However, some very large and highly regarded national studies do not offer the subjects any option to define their various eating occasions. Therefore, such surveys must be extensively examined to determine the most suitable definition of breakfast. The earlier the hour at which a breakfast meal might be considered, the more likely it was to pick up late night consumers including quite likely, shift-workers. Equally, the later the cut-off for defining the hour the breakfast intake might cease, the more likely it is to include foods more typical of lunch than breakfast. Thus, an iterative process was needed to identify the most likely period over which breakfast would be consumed. It may well be that a general recommendation to those involved in designing dietary surveys would be to either ask that the respondents choose a term to define the meal consumed, one of which would be breakfast or, at a minimum, to define the hour of rising.

There is considerable interest in the role of consuming and skipping breakfast on health outcomes and also on nutrient related outcomes. The study of breakfast skipping varies according to how such a practice is defined. In studies involving a single 24-h recall, breakfast intake can be readily dichotomized into ‘skippers’ and ‘consumers’. However, in studies of longer duration or of multiple 24-h recalls, subjects may be breakfast skippers if they skip breakfast on all days of the study. Breakfast consumers might be defined by the intake of a breakfast on all survey days. “Irregular” breakfast consumers lie in between and may be breakfast consumers on just one or on several days of the study. There is no agreement as to how to define skippers, irregular and regular breakfast consumers and this contributes to variation in conclusions reached as to the impact of breakfast on overall nutrient intake. This extends to the manner in which total daily nutrient intake is influenced by breakfast intake.

Energy under-reporting is a major phenomenon of all dietary surveys [ 43 ]. Objective techniques exist which give a very accurate measure of energy expenditure which in the short term and in a weight stable condition, can be equated to energy intake. Such techniques include at one end the use of stable isotopes such as doubly labelled water or at the other end, heart rate output. A crude estimate of energy requirements can be computed from equations relating age, gender, weight and height to basal metabolic rate which combined with an agreed multiple can yield a crude cut off point to indicate energy under-reporting. In some studies, energy under-reporters are eliminated before the data analysis. In others, energy under-reporting is ignored. Either way, it remains impossible to accurately state on an individual level, which food were under-reported in the estimation of overall energy intake. Under-reporting of a given food may involve under-reporting of the frequency of eating occasions or under-reporting of serving size at a given eating occasion. If skipping breakfast or the selection of some particular type of breakfast can influence energy intake, then it would make sense that comparisons adjusted for energy intake. The exclusion of energy under-reporters from large nationally representative surveys will in effect create the problem of the distortion of demographic balance since under-reporters are at a higher probability of being female, overweight and of lower socio-economic status.

Nutritional supplements are frequently consumed at that time of the day which coincides with breakfast intake and unless accounted for can lead to a significant distortion in the interpretation of nutrient intake patterns. One US study examined the impact of dietary supplements among breakfast consumers and showed that supplement usage significantly improved overall daily intake for vitamins A, B6, C and D and niacin and also improved daily intakes of magnesium, iron and zinc [ 44 ]. Breakfast studies should confine their analysis to nutrients derived from breakfast foods and not nutritional supplements. That is not to diminish the importance of the latter in the diets of many people. However, to develop dietary and food guidelines for breakfast, the focus should be on foods.

Given the need to relate the quality of breakfast eating patterns to overall daily nutrient intake, some measure of the overall quality of the daily diet must be used. Knowing that breakfast consumption leads to an overall improvement of mean daily nutrient intakes cannot address the question as to whether it has improved some more global definition of dietary quality. Many such measure of diet quality exist. German studies have developed a breakfast quality index (BQI) which simply measures how food and nutrient intakes at breakfast meet with some predefined standard of intake of selected nutrients [ 18 ]. This is useful, but it does not allow breakfast eating or breakfast skipping habits to be related to a global diet quality index. Examples of such include: The Healthy Eating Index, Alternate Healthy Eating Index, MedDietScore, PREDIMED Mediterranean Diet Score, and the Dutch Healthy Diet-Index [ 45 ]. Other approaches involve the Mean Adequacy Ratio (MAR) and the Nutrient Rich Food (NRF) index [ 26 ] In the present international collaborative study, overall dietary quality will be assessed using the NRF index, drawing on local nutritional standards. The advantage of the NRF is that it relies on the intake of nutrients, instead of food groups such as used in the Healthy Eating Index. Whilst food group data might be valuable for within-database analysis, the very significant variation in the classification of food groups makes this extremely problematic to compare between datasets and countries, and thereby to reach common conclusions.

8. Conclusions

The IBRI project is the first trans-Atlantic international collaborative study on the nutritional quality of breakfast that is based representative samples of the population in six different countries. In each country, analyses will establish the frequency of breakfast intake as well as energy and nutrient intakes from breakfast alone and from the total diet. The project objective is to formulate a set of breakfast-specific dietary guidelines that are both nutrient and food based. While similarities in energy intakes at breakfast may exist across countries, there is also considerable diversity in the local choices of breakfast foods and in the cultural context of the breakfast meal itself. The timing and location of breakfast can also vary widely across countries and population subgroups.

This international project will be based on multiple dietary intake databases that range from 1-day 24 h recall to 7-day diet records that are publicly available. These dietary surveys vary in data collection procedures and are linked to different national nutrient composition databases. In general, nutrient composition of foods is expressed in g, mg, or mcg per 100 g edible portion. However, not all nutrients are available for all countries; the inclusion of added, free and total sugars can be problematic. Multiple standards for nutrient adequacy exist, ranging from Codex values, to values set by the European Union, the World Health Organization and local health regulatory agencies, including the Food and Drug Administration in the US. Whereas nutrient values in the US are typically expressed per serving size, nutrient labels in the EU are generally based on 100 g reference amounts.

Notwithstanding these variations, the project will seek to harmonize the analysis of national databases to the maximum possible and to present the data on nutrient intake in such a manner to allow for cross country comparisons. A modeling component of the project will discuss how prevailing food choices for breakfast can be optimized to achieve nutrient rich breakfasts that best conform to the current dietary guidelines.

Nutrient density of the total diet will be assessed using the Nutrient Rich Foods (NRF) [ 26 ], initially developed to score nutrient density of individual foods. The present variant will be used to assess the quality of the total diet by measuring nutrient intakes per reference amount (2000 kcal). The NRF9.3 score is based on 9 qualifying nutrients and 3 disqualifying nutrients. The qualifying nutrients are protein, fiber, vitamin A, vitamin C, vitamin D, calcium, iron, potassium and magnesium. The disqualifying nutrients are saturated fat, added sugar and sodium. The NRF9.3 algorithm is the sum of the percent daily values for the 9 qualifying nutrients minus the sum of daily values of 3 disqualifying nutrients. The NRF family of nutrient density scores has been fully described in previously published research.

The overall daily intake of each nutrient for each subject will be expressed as a percentage of the reference daily intake where values for nutritional labelling will be used from EU, US and Canadian standards. Values above 100% will capped at the 100th mark. To allow for comparisons across countries, population samples will be stratified by NRF tertiles. Finally, for the upper tertile, which is indicative of the highest level of overall daily nutritional quality, the nutrient intakes at breakfast will be determined. These values will be used to guide quantitative dietary guidelines for breakfast.

Acknowledgments

The International Breakfast Research Initiative project was funded by Cereal Partners Worldwide (data analyses and publication costs). Data analyses for US and Canada were funded by General Mills Inc.

Author Contributions

M.J.G. prepared the first draft for comments by all authors. Subsequent and final drafts were also prepared in that manner.

Conflicts of Interest

In addition to declaring potential conflicts, the authors devised a Governing Principles outlining their rights and duties in this project. This was signed by all researchers or their institutions and the project sponsors. A copy of the document is included in the supplementary material. The following authors received an honorarium from the sponsor, Cereal Partners Worldwide, for their contribution to the project: M.J.G., F.T., B.L., F.V., L.M. and F.B. Research grants were received by B.L., G.V.M. and S.F. for their respective institutions in generating data; S.B., A.D. and F.V. received funding from General Mills, Inc. for their contribution to this project; G.M. and S.H. are employed by Cereal Partners Worldwide; J.S. is employed by General Mills.