Which nutrient's absorption is not impaired by the aging process

An Introduction to Nutrition

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Table of Contents About the Authors................................................................................................................. 1 Acknowledgments ................................................................................................................. 3 Dedications ............................................................................................................................. 4 Preface..................................................................................................................................... 5 Chapter 1: Nutrition and You ............................................................................................. 9

Defining Nutrition, Health, and Disease .................................................................................................... 12 What Are Nutrients? .................................................................................................................................... 18 The Broad Role of Nutritional Science....................................................................................................... 26 Health Factors and Their Impact................................................................................................................ 36 Assessing Personal Health........................................................................................................................... 50 A Fresh Perspective: Sustainable Food Systems ....................................................................................... 55 End-of-Chapter Exercises ............................................................................................................................ 63

Chapter 2: Achieving a Healthy Diet ............................................................................... 65 A Healthy Philosophy toward Food............................................................................................................ 69 What Is Nutritional Balance and Moderation? ......................................................................................... 74 Understanding the Bigger Picture of Dietary Guidelines ........................................................................ 82 National Goals for Nutrition and Health: Healthy People 2020 .............................................................. 88 Recommendations for Optimal Health ...................................................................................................... 95 Understanding Daily Reference Intakes .................................................................................................. 101 Discovering Nutrition Facts ...................................................................................................................... 106 When Enough Is Enough............................................................................................................................ 115 Nutrition and the Media............................................................................................................................ 119 End-of-Chapter Exercises .......................................................................................................................... 123

Chapter 3: Nutrition and the Human Body ................................................................. 125 The Basic Structural and Functional Unit of Life: The Cell ................................................................... 128 Digestion and Absorption.......................................................................................................................... 134 Nutrients Are Essential for Organ Function............................................................................................ 142 Energy and Calories ................................................................................................................................... 152 Disorders That Can Compromise Health ................................................................................................. 156 End-of-Chapter Exercises .......................................................................................................................... 163

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Chapter 4: Carbohydrates ............................................................................................... 165 A Closer Look at Carbohydrates ............................................................................................................... 169 Digestion and Absorption of Carbohydrates ........................................................................................... 176 The Functions of Carbohydrates in the Body.......................................................................................... 188 Looking Closely at Diabetes ...................................................................................................................... 194 Health Consequences and Benefits of High-Carbohydrate Diets .......................................................... 202 Carbohydrates and Personal Diet Choices............................................................................................... 212 The Food Industry: Functional Attributes of Carbohydrates and the Use of Sugar Substitutes .......219 End-of-Chapter Exercises .......................................................................................................................... 231

Chapter 5: Lipids ............................................................................................................... 233 What Are Lipids? ........................................................................................................................................ 236 How Lipids Work ........................................................................................................................................ 243 Digestion and Absorption of Lipids .......................................................................................................... 252 Understanding Blood Cholesterol ............................................................................................................ 257 Balancing Your Diet with Lipids ............................................................................................................... 263 Lipids and the Food Industry .................................................................................................................... 268 Lipids and Disease ...................................................................................................................................... 272 A Personal Choice about Lipids ................................................................................................................ 276 End-of-Chapter Exercises .......................................................................................................................... 281

Chapter 6: Proteins ........................................................................................................... 282 Defining Protein ......................................................................................................................................... 285 The Role of Proteins in Foods: Cooking and Denaturation.................................................................... 293 Protein Digestion and Absorption............................................................................................................ 296 Protein’s Functions in the Body ............................................................................................................... 300 Diseases Involving Proteins ...................................................................................................................... 308 Proteins, Diet, and Personal Choices........................................................................................................ 314 End-of-Chapter Exercises .......................................................................................................................... 333

Chapter 7: Nutrients Important to Fluid and Electrolyte Balance ......................... 335 Overview of Fluid and Electrolyte Balance.............................................................................................. 338 Water’s Importance to Vitality................................................................................................................. 342 Regulation of Water Balance..................................................................................................................... 346 Electrolytes Important for Fluid Balance ................................................................................................ 354 Consequences of Deficiency or Excess ..................................................................................................... 373 Water Concerns .......................................................................................................................................... 378 Popular Beverage Choices ......................................................................................................................... 389 End-of-Chapter Exercises .......................................................................................................................... 402

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Chapter 8: Nutrients Important As Antioxidants ...................................................... 403 Generation of Free Radicals in the Body ................................................................................................. 406 Antioxidant Micronutrients...................................................................................................................... 413 The Whole Nutrient Package versus Disease .......................................................................................... 438 End-of-Chapter Exercises .......................................................................................................................... 444

Chapter 9: Nutrients Important for Bone Health ...................................................... 445 Bone Structure and Function.................................................................................................................... 448 Bone Mineral Density Is an Indicator of Bone Health ............................................................................ 455 Micronutrients Essential for Bone Health: Calcium and Vitamin D ..................................................... 457 Other Essential Micronutrients for Bone Health: Phosphorous, Magnesium, Fluoride, and Vitamin K ................................................................................................................................................................... 473 Osteoporosis ............................................................................................................................................... 484 Risk Factors for Osteoporosis ................................................................................................................... 488 Osteoporosis Prevention and Treatment ................................................................................................ 493 Deficiency, Supplementation, and Choices ............................................................................................. 498 End-of-Chapter Exercises .......................................................................................................................... 505

Chapter 10: Nutrients Important for Metabolism and Blood Function ................ 507 Blood’s Function in the Body and in Metabolism Support .................................................................... 509 Metabolism Overview ................................................................................................................................ 516 Vitamins Important for Metabolism and for Blood Function and Renewal ........................................ 523 Minerals Important for Metabolism and for Blood Function and Renewal......................................... 537 Iron-Deficiency Anemia............................................................................................................................. 545 End-of-Chapter Exercises .......................................................................................................................... 552

Chapter 11: Energy Balance and Body Weight............................................................ 553 Indicators of Health: Body Mass Index, Body Fat Content, and Fat Distribution................................557 Balancing Energy Input with Energy Output .......................................................................................... 562 Too Little or Too Much Weight: What Are the Health Risks?................................................................ 575 Dietary, Behavioral, and Physical Activity Recommendations for Weight Management ..................581 End-of-Chapter Exercises .......................................................................................................................... 589

Chapter 12: Nutrition through the Life Cycle: From Pregnancy to the Toddler Years .................................................................................................................................... 591

The Human Life Cycle ................................................................................................................................ 594 Pregnancy and Nutrition........................................................................................................................... 598 Infancy and Nutrition................................................................................................................................ 614 Nutrition in the Toddler Years ................................................................................................................. 632 End-of-Chapter Exercises .......................................................................................................................... 641

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Chapter 13: Nutrition through the Life Cycle: From Childhood to the Elderly Years .................................................................................................................................... 643

The Human Life Cycle Continues.............................................................................................................. 646 Childhood and Nutrition ........................................................................................................................... 651 Puberty and Nutrition ............................................................................................................................... 659 Older Adolescence and Nutrition ............................................................................................................. 665 Young Adulthood and Nutrition............................................................................................................... 670 Middle Age and Nutrition ......................................................................................................................... 676 Old Age and Nutrition................................................................................................................................ 681 End-of-Chapter Exercises .......................................................................................................................... 687

Chapter 14: Nutrition and Society: Food Politics and Perspectives ....................... 689 Historical Perspectives on Food ............................................................................................................... 692 The Food Industry...................................................................................................................................... 699 The Politics of Food.................................................................................................................................... 708 Food Cost and Inflation ............................................................................................................................. 714 The Issue of Food Security ........................................................................................................................ 718 Nutrition and Your Health ........................................................................................................................ 726 Diets around the World ............................................................................................................................. 732 End-of-Chapter Exercises .......................................................................................................................... 744

Chapter 15: Achieving Optimal Health: Wellness and Nutrition ............................ 746 Diet Trends and Health.............................................................................................................................. 749 Fitness and Health ..................................................................................................................................... 763 Threats to Health ....................................................................................................................................... 770 Foodborne Illness and Food Safety .......................................................................................................... 782 Start Your Sustainable Future Today....................................................................................................... 797 Careers in Nutrition................................................................................................................................... 802 End-of-Chapter Exercises .......................................................................................................................... 806

Chapter 16: Appendix A ................................................................................................... 807

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About the Authors

Maureen Zimmerman

Dr. Maureen Zimmerman earned her undergraduate degree in Nutrition and Dietetics at Arizona State University, a Master’s Degree in Public Health from the University of Hawaii, and a Doctorate in Educational Leadership, with a specialization in educational research, from Northern Arizona University. She is a Registered Dietitian and has been a residential faculty member at Mesa Community College in Mesa, Arizona since 1991. She has been involved in many aspects of college life, most of them related to improving teaching and learning. She works indefatigably to assure that students enjoy their learning journey, regularly applying learning science to the online and ground classrooms. She is active every day of the week either practicing yoga, biking, hiking, tap dancing, or running. She enjoys reading a variety of genres, and likes to drink good coffee in the company of friends and family. She watches international films regularly, and tries to eat many fruits and vegetables every day. Her food first philosophy is summed up in this statement: “Enjoy real food, enjoy it with others, enjoy it in just the right amounts.”

Beth Snow

Dr. Beth Snow earned a BS (Hons) in Biochemistry (with a minor in Drama) from McMaster University in 1999, an MS in Human Biology & Nutritional Sciences from the University of Guelph in 2000, and a PhD in Human Nutrition from the University of British Columbia in 2006. She also holds a Credentialed Evaluator designation from the Canadian Evaluation Society. Her PhD research focused on the effects of prenatal alcohol exposure on the developing fetal skeleton and she has published in the journals Bone, Alcohol, and Alcoholism: Clinical & Experimental Research. Following her PhD training, she spent two years working at the British Columbia Centre of Excellence for Women’s Health, where she ran an interdisciplinary research training

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program. She currently works as an Evaluation Specialist in Public Health in Vancouver, BC, Canada, where she also teaches at the University of British Columbia and the Justice Institute of British Columbia. Her teaching philosophy involves empowering students to take ownership of their own learning; she uses active learning techniques and encourages students to apply what they learn to real life. Being a lifelong learner herself, Beth is currently working on a Masters of Business Administration at the University of British Columbia, with the goal of combining knowledge about organizations with her health research expertise in order to help get research evidence into Public Health practice. In addition to her busy career, Beth is a true foodie who always makes time to cook and share good food and she enjoys hiking, running, yoga, and, being a Canadian, playing ice hockey.

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Acknowledgments

It takes a village to create a textbook and we are deeply indebted to all those who helped us make this book a reality. First and foremost, our deepest thanks go out to all those who reviewed our chapters and gave us thoughtful feedback on how to make them even better:

• Patricia Abraham, Arkansas State University • Jessica Adams, Colby-Sawyer College • Christine Bieszczad, Colby-Sawyer College • Douglas Bruce, Laney College • Kathleen L. Deegan, California State University, Sacramento • Lindsay Edwards, Hardin-Simmons University • Cathy Headley, Judson University • Laura Hutchinson, Holyoke Community College • Christa Koval, Colorado Christian University • Beth Ann Krueger, Central Arizona College–Aravaipa Campus • Patrick Mathews, Friends University • Jill O’Malley, Erie Community College • Ana Otero, Emmanuel College • Alfred Ordman, Beloit College • Paula Vineyard Most, John A. Logan College • Linda Wright, Dixie State College of Utah

We are especially thankful to Teresa Fung for her expert content editing. Teresa has a keen eye for scientific accuracy. Because she is steeped in the nutrition literature, her input has been invaluable.

The development editors included Melissa Lingohr-Smith, Lisa Benjamin, and Danielle Dresden.

We are also very grateful for the incredible support we received from the teams at Unnamed Publisher and The Research Masters. Melissa Yu of Unnamed Publisher and Amy Bethea of The Research Masters have provided such invaluable support in managing the creation of this book—it could not have happened without them. We would also like to thank Michael Boezi and all the others at Unnamed Publisher who have championed a nonmajors nutrition book.

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Dedications

Maureen Zimmerman

Many people have shaped my professional and personal life. I would be remiss not to acknowledge those who saw potential and hired me in 1991 to develop a nutrition program at Mesa Community College. To those who initiated and maintained the stellar teaching and learning movement in the Maricopa Community College District, I am grateful. To my colleagues and the doctoral faculty who helped form my teaching practice, thank you. Succor comes from my family. My five children, in particular, experienced my nutritional philosophies even before the cradle. They brought hummus to school before it ever hit the grocery store shelves. Studying and teaching nutrition has been a fulfilling part of my life; I am grateful to all who have influenced me, most especially the thousands of students I have learned with through the years.

Beth Snow

I dedicate this book to my mother, Ann Snow, who taught me the fun of cooking, and my father, the late Jack Snow, who showed me the amazing world of biology. Marrying these two interests led to my pursuit of an education in nutritional sciences and, ultimately, to authoring this textbook.

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Preface

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.

Focus on Sustainability

People are increasingly interested in sustainable food issues. They are looking for favorable ways to impact not only their health, but also the environment and their local economy. However, misinformation about how one can make a positive impact abounds. By highlighting effective sustainable food behaviors, supported by science, this book will provide you with a significant resource for increasing the sustainable practices in your day-to-day life.

Organization

This book is organized using a functional approach, which means that the material is organized around physiological functions, such as fluid and electrolyte balance, antioxidant function, bone health, energy and metabolism, and blood health, instead of organizing it strictly by nutrient. This makes the information easier to understand, retain, and apply to your own life. As this text explores the relationship between nutrition and physiology, you will receive a “behind the scenes” examination of health and disease in the body.

• In Chapter 1 "Nutrition and You", we provide an overview of nutrition as an evidence-based science and explore the concepts of health, wellness, and disease. We also provide an introduction to the different types of nutrients, health factors, personal health assessment, and the concept of sustainable food systems.

• In Chapter 2 "Achieving a Healthy Diet", we explore the tools you can use to achieve a healthy diet, as well as important nutrition concepts like balance and moderation.

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• In Chapter 3 "Nutrition and the Human Body", because we know that you may not have a background in biology, we start with a tour through the human body, from the single cell to the full organism, we set up for a discussion about the processes of digestion and absorption, followed by explorations of the other organ systems. After that, we discuss the concept of energy and calories. We also discuss some disorders and diseases related to nutritional health.

• In Chapter 4 "Carbohydrates", we explore the many types of carbohydrates, including their functions. We also take a look at diabetes and at sugar substitutes.

• In Chapter 5 "Lipids", we look at the types, structure, and roles of lipids, and we explain the different types of cholesterol in the blood. We also explore topics of interest such as omega-3 and omega-6 fatty acids and trans fats.

• In Chapter 6 "Proteins", we cover the structure and roles of protein, and explore the consequences of getting too little or too much protein in your diet. Tips for getting the right amount and quality of protein, as well as a look at special populations, such as the elderly and athletes, are also covered.

• In Chapter 7 "Nutrients Important to Fluid and Electrolyte Balance", we look at the nutrients important to fluid and electrolyte balance, including water, sodium, chloride, and potassium. We also look at sports drinks, caffeinated beverages, and alcohol.

• In Chapter 8 "Nutrients Important As Antioxidants", nutrients important as antioxidants are explored, starting with an explanation of what oxidation and antioxidants are, then looking at vitamins E, C, and A, selenium, and phytochemicals.

• In Chapter 9 "Nutrients Important for Bone Health", we delve into nutrients important for bone health. First, we explore the structure and function of bones, and then calcium, vitamin D, phosphorus, magnesium, fluoride, and vitamin K. A look at osteoporosis and at supplements rounds out this chapter.

• In Chapter 10 "Nutrients Important for Metabolism and Blood Function", we look at the nutrients important in energy metabolism and blood health, by first looking at blood and at metabolism, and then discussing the B vitamins, vitamin K, magnesium, iron, zinc, and other micronutrients. We also explore iron-deficient anemia and iron toxicity.

• In Chapter 11 "Energy Balance and Body Weight", we take a look at the obesity epidemic and eating disorders—the extremes of energy imbalance—and we look at evidence-based recommendations for maintaining a healthy weight.

• Chapter 12 "Nutrition through the Life Cycle: From Pregnancy to the Toddler Years" is the first of two chapters exploring nutrition through

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the life cycle and it looks at pregnancy through the toddler years. Topics include pregnancy, breastfeeding, introducing solid foods, and nutrition during the toddler years.

• In Chapter 13 "Nutrition through the Life Cycle: From Childhood to the Elderly Years" we continue to explore nutrition through the life cycle, this time looking at childhood to the elderly years.

• In Chapter 14 "Nutrition and Society: Food Politics and Perspectives", we explore food politics, sustainability, the food industry, food security, and diets from around the world.

• In Chapter 15 "Achieving Optimal Health: Wellness and Nutrition", we look at a number of topics of interest to students: diet trends, food supplements and food replacements, fitness, chronic diseases, and food safety. Also included in this chapter are tips for living a sustainable lifestyle, and information about careers in nutrition.

Features

Each chapter starts with a “Big Idea,” which provides a preview of the main theme of the chapter.

You Decide challenges you to apply what you are learning about nutrition topics—sometimes controversial ones—to your own life.

Key Takeaways and Key Terms provide the key take-home messages and definitions from each section, helping you to focus on the main points you should be learning.

Discussion Starters are questions that can prompt discussions with fellow students and your instructor to examine and extend what you’ve learned in the chapter.

There are many Videos available online and it is not always clear which ones have reliable information. We have done the legwork for you by providing interesting videos from reputable sources to accompany and highlight the content. Similarly, we provide links to useful online learning tools through the Interactive feature.

Most of the databases for diet analysis programs primarily feature industrial food. As we promote sustainable food activities in our text, we cannot use these common diet analysis programs because they do not cater to students who eat real food prepared at home. As a result, we provide links to http://www.choosemyplate.gov/ throughout the text. You will be encouraged to create your own meals, shop

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smarter, choose wisely, and, at the same time, foster an active attitude toward food sustainability.

Every chapter ends with Exercises, which are activities that can be used to test what has been learned in the chapter and may be used by your instructor as homework or assignment questions. There are exercises at three different levels (It’s Your Turn, Apply It, and Expand Your Knowledge) to meet the varied needs of different students.

Please do not use this book to substitute for professional medical care or advice. If you have medical concerns or questions, always seek guidance from a health-care professional. The authors and publisher are not responsible for the accuracy of any content added by faculty.

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Chapter 1

Nutrition and You

Big Idea

Nutrition is an evidence-based science. Nutritional scientists continuously advance our knowledge of nutrition by building on prior research.

As we get started on our journey into the world of health and nutrition, our first focus will be to demonstrate 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 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 grandfather complained to his doctor of symptoms of peptic ulcer, he was probably told to avoid spicy foods, alcohol, and coffee, and to manage his stress. In the early twentieth century, the medical community thought peptic ulcers were caused by what you ate and drank,

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and by 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 meal times. 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 the 1980s, Australian physicians Barry Marshall and Robin WarrenCurrey, R. “Ulcers—The Culprit Is H. Pylori!” National Institutes of Health, Office of Science Education. Accessed November 10, 2011. http://science.education.nih.gov/ home2.nsf/Educational+ResourcesResource+FormatsOnline+Resources+High+ School/928BAB9A176A71B585256CCD00634489 proposed a radical hypothesis—that the cause of ulcers was bacteria that could survive in the acidic environment of the stomach and small intestine. They met with significant opposition to their hypothesis but they persisted with their research. Their research led to an understanding that the spiral shape of the bacterium H. pylori allows it to penetrate the stomach’s mucous lining, where it secretes an enzyme that generates substances to neutralize the stomach’s acidity. This weakens the stomach’s protective mucous, making the tissue more susceptible to the damaging effects of acid, leading to the development of sores and ulcers. H. pylori also prompt the stomach to produce even more acid, further damaging the stomach lining. Marshall actually drank a dish of H. pylori hoping to give himself an ulcer to prove his point. A few days later he was vomiting and had inflamed tissue in his stomach. The presence of H. pylori was confirmed. He then took an antibiotic and the symptoms of H. pylori infection dissipated. Experimental success? It still took years for the medical community to be entirely convinced of the link between peptic ulcers and H. pylori.

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 health-care 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 health-care providers that peptic ulcers are a curable condition

Chapter 1 Nutrition and You

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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.

The H. pylori discovery was made recently, overturning a theory applied in our own time. The demystification of disease requires the continuous forward march of science, overturning old, traditional theories and discovering new, more effective ways to treat disease and promote health. 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.

You Decide

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

A primary goal of this text is to provide you with information backed by nutritional science, and with a variety of resources that use scientific evidence to optimize health and prevent disease. 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, and recommendations that will promote health and prevent disease.

“The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny...’”

- Isaac Asimov (January 2, 1920–April 6, 1992)

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1.1 Defining Nutrition, Health, and Disease

LEARNING OBJECTIVE

1. Explain the terms nutrition, health, health promotion, and disease prevention.

Your View of Food

Americans are bombarded with television programs that show where to find the best dinners, pizzas, and cakes, and the restaurants that serve the biggest and juiciest burgers. Other programs feature chefs battling to prepare meals, and the top places to burst your belly from consuming atomic chicken wings and deli sandwiches longer than a foot. There are also shows that feature bizarre foods from cultures around the world. How do you use the information from popular network food shows to build a nutritious meal? You don’t—these shows are for entertainment. The construction of a nutritious meal requires learning about which foods are healthy and which foods are not, how foods and nutrients function in your body, and how to use scientific resources. This text is designed to provide you with the information necessary to make sound nutritional choices that will optimize health and help prevent disease.

Chapter 1 Nutrition and You

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The word nutrition first appeared in 1551 and comes from the Latin word nutrire, meaning “to nourish.” Today, we define nutrition1 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 science2 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 is lacking in many ways, from not containing the proper amounts of essential nutrients, to being too speedily consumed, to being only meagerly satisfying. Dietitians are nutrition professionals who integrate their knowledge of nutritional science into helping people achieve a healthy diet and develop good dietary habits. The Academy of Nutrition and Dietetics (AND) is the largest organization of nutrition professionals worldwide and dietitians registered with the AND are committed to helping Americans eat well and live healthier lives. To learn more from the AND’s nutritional advice, visit http://www.eatright.org/ default.aspx.

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. For the next few minutes, take some time to view snapshots of the insides of the refrigerators of American mechanics, doctors, school teachers, hunters, short- order cooks, college students, vegans, and more. Visit Mark Menjivar’s portrait exhibition, “You Are What You Eat” (Note 1.7 "Interactive 1.1"). Menjivar hopes these images will invoke new thoughts about, “How we care for our bodies. How we care for others. And how we care for the land.” As you look at these images think about your personal health, the health of your family and friends, and the health of this planet. These hopes encompass the inspirations for this book.

1. The sum of all processes involved in how organisms obtain nutrients, metabolize them, and use them to support all of life’s processes.

2. The investigation of how an organism is nourished, and how nourishment affects personal health, population health, and planetary health.

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1.1 Defining Nutrition, Health, and Disease 13

Interactive 1.1

Mark Menjivar has traveled around the United States taking photographs of the contents of refrigerators of numerous types of people. The portraits are available for viewing on his website under “You Are What You Eat.”

http://markmenjivar.com/you-are-what-you-eat/statement/

Nutrition and Health and Disease

In 1946, the World Health Organization (WHO) defined health3 as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.”World Health Organization. Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, June 19–July 22, 1946. http://www.who.int/suggestions/faq/en/ This definition was adopted into the WHO consititution in 1948 and has not been ammended since. A triangle is often used to depict the equal influences of physical, mental, and social well-being on health. Disease4 is defined as any abnormal condition affecting the health of an organism, and is characterized by specific signs and symptoms. Signs refer to identifying characteristics of a disease such as swelling, weight loss, or fever. Symptoms are the features of a disease recognized by a patient and/or their doctor. Symptoms can include nausea, fatigue, irritability, and pain. Diseases are broadly categorized as resulting from pathogens (i.e., bacteria, viruses, fungi, and parasites), deficiencies, genetics, and 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.

3. A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.

4. Any abnormal condition that affects the health of an organism and is characterized by specific signs and symptoms.

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1.1 Defining Nutrition, Health, and Disease 14

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

Public Health and Disease Prevention

In 1894, the first congressional funds were appropriated to the US Department of Agriculture (USDA) for the study of the relationship between nutrition and human health. Dr. Wilbur Olin Atwater was appointed as the Chief of Nutrition Investigations and is accoladed as the “Father of Nutrition Science” in America.Combs, G.F. “Celebration of the Past: Nutrition at USDA.” J Nutr 124, no. 9 supplement (1994): 1728S–32S. http://jn.nutrition.org/content/124/9_Suppl/ 1728S.long Under his guidance the USDA released the first bulletin to the American public that contained information on the amounts of fat, carbohydrates, proteins, and food energy in various foods. Nutritional science advanced considerably in these early years, but it took until 1980 for the USDA and the US Department of Health and Human Services (HHS) to jointly release the first edition of Nutrition and Your Health: Dietary Guidelines for Americans.

Although wide distribution of dietary guidelines did not come about until the 1980s, many historical events that demonstrated the importance of diet to health preceded their release. Assessments of the American diet in the 1930s led President Franklin D. Roosevelt to declare in his inaugural address on January 20, 1937, “I see one-third of our nation is ill-housed, ill-clad, and ill-nourished.” From the time of Atwater until the onset of the Great Depression nutritional scientists had discovered many of the vitamins and minerals essential for the functioning of the human body. Their work and the acknowledgement by President FDR of the nutritional inadequacy of the American diet evoked a united response between scientists and government leading to the enrichment of flour, the development of school lunch programs, and advancements of nutritional education in this country.

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Figure 1.2 The Federal Government’s New and Improved Tool of Nutritional Communication

In the latter part of the twentieth century nutritional scientists, public health organizations, and the American public increasingly recognized that eating too much of certain foods is linked to chronic diseases. We now know that diet-related conditions and diseases include hypertension (high blood pressure), obesity, Type 2 diabetes, cardiovascular disease, some cancers, and osteoporosis. These diet-related conditions and diseases are some of the biggest killers of Americans. The HHS reports that unhealthy diets and inactivity cause between 310,000 and 580,000 deaths every single year.Center for Science in the Public Interest. “Nutrition Policy.” Accessed March 1, 2012. http://www.cspinet.org/nutritionpolicy/ nutrition_policy.html#disease According to the USDA, eating healthier could save Americans over $70 billion per year and this does not include the cost of obesity, which is estimated to cost a further $117 billion per year.Combs, G.F. “Celebration of the Past: Nutrition at USDA.” J Nutr 124, no. 9 supplement (1994): 1728S–32S. http://jn.nutrition.org/content/124/9_Suppl/1728S.long Unfortunately, despite the fact that the prevalence of these diseases can be decreased by healthier diets and increased physical activity, the CDC reports that the federal government spends one thousand times more to treat disease than to prevent it ($1,390 versus $1.21 per person each year).Combs, G.F. “Celebration of the Past: Nutrition at USDA.” J Nutr 124, no. 9 supplement (1994): 1728S–32S. http://jn.nutrition.org/content/124/ 9_Suppl/1728S.long In 2010, the new edition of the dietary guidelines identified

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obesity as the number one nutritional-related health problem in the United States and established strategies to combat its incidence and health consequences in the American population. A 2008 study in the journal Obesity reported that if current trends are not changed, 100 percent of Americans will be overweight or obese in 2048!Wang Y, et al. “Will All Americans Become Overweight or Obese? Estimating the Progression and Cost of the US Obesity Epidemic.” Obesity 10, no. 16 (October 2008): 2323–30. http://www.nature.com/oby/journal/v16/n10/full/ oby2008351a.html In 2011, the US federal government released a new multimedia tool that aims to help Americans choose healthier foods from the five food groups (grains, vegetables, fruits, dairy, and proteins). The tool, called “Choose MyPlate,” is available at choosemyplate.gov.

KEY TAKEAWAYS

• Health is defined as “a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.”World Health Organization. “WHO definition of health.” http://www.who.int/ about/definition/en/print.html.

• Disease is defined as any abnormal condition that affects the health of an organism, and is characterized by specific signs and symptoms.

• Disease affects all three aspects of the health triangle. • Good nutrition provides a mechanism to promote health and prevent

disease. • Diet-related conditions and diseases include obesity, Type 2 diabetes,

cardiovascular disease, some cancers, and osteoporosis. • It took until the 1980s for the US federal government to develop a diet-

related public policy designed to equip Americans with the tools to change to a healthier diet.

DISCUSSION STARTERS

1. How might the way we nourish our bodies affect planetary health? 2. Debate your classmates: Should the federal government be concerned

with what Americans eat?

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1.2 What Are Nutrients?

LEARNING OBJECTIVES

1. Define the word “nutrient” and identify the six classes of nutrients essential for health.

2. List the three energy-yielding nutrients and their energy contribution.

What’s in Food?

The foods we eat contain nutrients5. Nutrients are substances required by the body to perform its basic functions. Nutrients must be obtained from diet, since the human body does not synthesize them. Nutrients are used to produce energy, detect and respond to environmental surroundings, move, excrete wastes, respire

5. Substances required by the body that must be obtained from the diet.

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(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. Foods also contain nonnutrients that may be harmful (such as cholesterol, dyes, and preservatives) or beneficial (such as antioxidants). Nonnutrient substances in food will be further explored in Chapter 8 "Nutrients Important As Antioxidants".

Macronutrients

Nutrients that are needed in large amounts are called macronutrients6. There are three classes of macronutrients: carbohydrates, lipids, and proteins. These can be metabolically processed into cellular energy. The energy from macronutrients comes from their chemical bonds. This chemical energy is converted into cellular energy that is then utilized to perform work, allowing our bodies to conduct their basic functions. A unit of measurement of food energy is the calorie. On nutrition food labels the amount given for “calories” is actually equivalent to each calorie multiplied by one thousand. A kilocalorie (one thousand calories, denoted with a small “c”) is synonymous with the “Calorie” (with a capital “C”) on nutrition food labels. 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.

Carbohydrates

Carbohydrates7 are molecules composed of carbon, hydrogen, and oxygen. The major food sources of carbohydrates are grains, milk, fruits, and starchy vegetables like potatoes. Nonstarchy vegetables also contain carbohydrates, but in lesser quantities. Carbohydrates are broadly classified into two forms based on their chemical structure: fast-releasing carbohydrates, often called simple sugars, and slow-releasing carbohydrates.

Fast-releasing carbohydrates consist of one or two basic units. Examples of simple sugars include sucrose, the type of sugar you would have in a bowl on the breakfast table, and glucose, the type of sugar that circulates in your blood.

6. Nutrients that are needed in large amounts. Includes carbohydrates, lipids, proteins, and water.

7. Organic molecules composed of carbon, hydrogen, and oxygen. There are two basic forms: simple sugars and complex sugars.

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Slow-releasing carbohydrates are long chains of simple sugars that can be branched or unbranched. During digestion, the body breaks down all slow-releasing carbohydrates to simple sugars, mostly glucose. Glucose is then transported to all our cells where it is stored, used to make energy, or used to build macromolecules. Fiber is also a slow-releasing carbohydrate, but it cannot be broken down in the human body and passes through the digestive tract undigested unless the bacteria that inhabit the gut break it down.

One gram of carbohydrates yields four 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 starches. Glycogen and starches are slow-releasing carbohydrates.

Lipids

Lipids8 are also a family of molecules composed of carbon, hydrogen, and oxygen, but unlike carbohydrates, they are insoluble in water. Lipids are found predominately in butter, oils, meats, dairy products, nuts, and seeds, and in many processed foods. The three main types of lipids are triglycerides (triacylglycerols),

8. A family of organic compounds composed of carbon, hydrogen, and oxygen. They are insoluble in water. The three main types of lipids are triglycerides, phospholipids, and sterols.

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phospholipids, and sterols. The main job of lipids is to store energy. Lipids provide more energy per gram than carbohydrates (nine kilocalories per gram of lipids versus four kilocalories per gram of carbohydrates). In addition to energy storage, lipids serve as cell membranes, surround and protect organs, aid in temperature regulation, and regulate many other functions in the body.

Proteins

Proteins9 are macromolecules composed of chains of subunits called amino acids. Amino acids are simple subunits 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 four kilocalories of energy per gram; however providing energy is not protein’s most important function. Proteins provide structure to bones, muscles and skin, 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.

Water

There is one other nutrient that we must have in large quantities: water. Water does not contain carbon, but is composed of two hydrogens and one oxygen per molecule of water. More than 60 percent 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, a topic we will explore in detail in Chapter 7 "Nutrients Important to Fluid and Electrolyte Balance".

Micronutrients

Micronutrients10 are nutrients required by the body in lesser amounts, but are still essential for carrying out bodily functions. Micronutrients include all the essential minerals and vitamins. There are sixteen essential minerals and thirteen vitamins (See Table 1.1 "Minerals and Their Major Functions" and Table 1.2 "Vitamins and Their Major Functions" for a complete list and their major functions). In contrast to carbohydrates, lipids, and proteins, micronutrients are not directly used for making

9. Macromolecules composed of chains of organic monomeric subunits, called amino acids. Amino acids are simple monomers composed of carbon, oxygen, hydrogen, and nitrogen.

10. Nutrients needed in smaller amounts. Includes vitamins and minerals.

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energy, but they assist in the process as being 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.

Minerals

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 and macrominerals, such as calcium, magnesium, potassium, sodium, and phosphorus, are required in hundreds of milligrams. 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 1.1 Minerals and Their Major Functions

Minerals Major Functions

Macro

Sodium Fluid balance, nerve transmission, muscle contraction

Chloride Fluid balance, stomach acid production

Potassium Fluid balance, nerve transmission, muscle contraction

Calcium Bone and teeth health maintenance, nerve transmission, musclecontraction, blood clotting

Phosphorus Bone and teeth health maintenance, acid-base balance

Magnesium Protein production, nerve transmission, muscle contraction

Sulfur Protein production

Trace

Iron Carries oxygen, assists in energy production

Zinc Protein and DNA production, wound healing, growth, immune systemfunction

Iodine Thyroid hormone production, growth, metabolism

Selenium Antioxidant