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Nourish your mind and body with NUTRITION: CONCEPTS AND CONTROVERSIES. More conversational than a pure-science text, this book explores the essentials of nutrition--including how the body breaks down and uses food, food safety, sports nutrition and special nutritional needs throughout the human life cycle--and asks you to weigh in on relevant debates, such as world hunger, chronic diseases, dietary guidelines and eating patterns. Available with the MindTap learning platform, the 15th edition also offers self-quizzing and activities to propel your learning from memorization to mastery.
წელი:
2020
გამოცემა:
15th Edition
გამომცემლობა:
Cengage Learning
ენა:
english
გვერდები:
743
ISBN 10:
0357391764
ISBN 13:
9780357391761
ფაილი:
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შეგიძლიათ დატოვოთ გამოხმაურება წიგნის შესახებ და გააზიაროთ თქვენი გამოცდილება. სხვა მკითხველისთვის საინტერესო იქნება თქვენი მოსაზრება წაკითხული წიგნების შესახებ. მიუხედავად იმისა მოგწონთ თუ არა წიგნი, მასზე გულწრფელი და დეტალური მსჯელობა, ადამიანებს მისცემს საშუალებას იპოვონ ახალი წიგნები, რომლებიც მათ დააინტერესებთ.
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15th Edition

Edward Bock/Alamy Stock Photo

nutrition
concepts & controversies

Frances Sienkiewicz Sizer | Ellie Whitney

Australia

●

Brazil

●

Mexico

●

Singapore

●

United Kingdom

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United States

Nutrition: Concepts & Controversies, 15e

© 2020, 2017, Cengage Learning, Inc.

Frances Sienkiewicz Sizer and Ellie Whitney

Unless otherwise noted, all content is © Cengage.

Product Team Manager: Kelsey Churchman
Product Manager: Courtney Heilman
Content Manager: Carol Samet

ALL RIGHTS RESERVED. No part of this work covered by the copyright herein
may be reproduced or distributed in any form or by any means, except as
permitted by U.S. copyright law, without the prior written permission of the
copyright owner.

Production Service: MPS Limited
Text and Photo Researcher: Lumina Datamatics

For product information and technology assistance, contact us at
Cengage Customer & Sales Support, 1-800-354-9706

Art Director: Helen Bruno

or support.cengage.com.

Text Designer: Jennifer Wahi

For permission to use material from this text
or product, submit all requests online at

Cover Designer: Helen Bruno

www.cengage.com/permissions.

Cover Image: Edward Bock/Alamy Stock Photo
Compositor: MPS Limited

Library of Congress Control Number: 2018936387
ISBN: 978-1-337-90637-1
Loose-leaf Edition:
ISBN: 978-1-337-90695-1
Cengage
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Boston, MA 02210
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Printed in the United States of America
Print Number: 01		
Print Year: 2018

About the Authors
Frances Sienkiewicz Sizer
M.S., R.D.N., F.A.N.D., attended Florida State University ; where, in 1980,
she received her B.S., and in 1982 her M.S., in nutrition. She is certified as a
charter Fellow of the Academy of Nutrition and Dietetics. She is a founding
member and vice president of Nutrition and Health Associates, an information and resource center in Tallahassee, Florida, that maintains an ongoing
bibliographic database tracking research in more than 1,000 topic areas of
nutrition. Her textbooks include Life Choices: Health Concepts and Strategies;
Making Life Choices; The Fitness Triad: Motivation, Training, and Nutrition; and
others. She also authored Nutrition Interactive, an instructional college-level
nutrition CD-ROM that pioneered the animation of nutrition concepts in college classrooms. She has consulted with an advisory board of professors from

For our newest granddaughter,
Karen Ann Sizer. Welcome,
baby girl!
–Fran

around the nation with a focus on innovations in nutrition education. She
has lectured at universities and at national and regional conferences and supports local hunger and homelessness relief organizations in her community.

Eleanor Noss Whitney
Ph.D., received her B.A. in biology from Radcliffe College in 1960 and her
Ph.D. in biology from Washington University, St. Louis, in 1970. Formerly
on the faculty at Florida State University and a dietitian registered with the
Academy of Nutrition and Dietetics, she now devotes her time to research,
writing, and consulting in nutrition, health, and environmental issues. Her
earlier publications include articles in Science, Genetics, and other journals.
Her textbooks include Understanding Nutrition, Understanding Normal and
­Clinical Nutrition, Nutrition and Diet Therapy, and Essential Life Choices for
college students and Making Life Choices for high school students. Her most
intense interests presently include energy conservation, solar energy uses,
alternatively fueled vehicles, and ecosystem restoration. She is an activist
who volunteers full-time for the Citizens Climate Lobby.

To Max, Zoey, Emily, Rebecca,
Kalijah, and Duchess with love.
–Ellie

Brief Contents
Preface xiv

1 Food Choices and Human Health 1
2 Nutrition Tools—Standards and Guidelines 30
3 The Remarkable Body 67
4 The Carbohydrates: Sugar, Starch, Glycogen,
and Fiber

104

5 The Lipids: Fats, Oils, Phospholipids, and
Sterols

The five Dietary Reference Intake
tables are on pages A, B, and C
at the back of the book in this
edition, relocated there from the
front cover in previous editions.

144

6 The Proteins and Amino Acids 182
7 The Vitamins 218
8 Water and Minerals 270
9 Energy Balance and Healthy Body
Weight

317

10 Performance Nutrition 365
1 1 Nutrition and Chronic Diseases 404
12 Food Safety and Food Technology 440
13 Life Cycle Nutrition: Mother and Infant 484
14 Child, Teen, and Older Adult 526
15 Hunger and the Future of Food 567
Appendixes
Glossary

A-1

GL-1

Index IN-1

Contents
Preface

xiv

Chapter

Self Check

CONTROVERSY 1: Sorting Imposters from Real
Nutrition Experts 23

1

Food Choices and Human
Health 1
A Lifetime of Nourishment
The Diet–Health Connection

Chapter

3

Nutrient Recommendations

3

Think Fitness: Why Be Physically Active?
Other Lifestyle Choices

5

The Human Body and Its Food

5

The DRI Lists and Purposes

11

Think Fitness: Recommendations for Daily
Physical Activity 39

Diet Planning Using the USDA Eating
Patterns 39

13

14

The Food Groups and Subgroups

14

Choosing Nutrient-Dense Foods

Can I Trust the Media for Nutrition Information?
National Nutrition Research

17

16

Diet Planning

39
42

43

MyPlate Educational Tool

Changing Behaviors 17

45

Flexibility of the USDA Eating Patterns

18

Food Lists for Weight Management

Taking Stock and Setting Goals

36

Dietary Guidelines for Americans 36
9

12

The Science of Nutrition

35

35

Why Are Daily Values Used on Labels?

How, Exactly, Can I Recognize a Nutritious Diet?
Why People Choose Foods

32

33

Setting Energy Requirements
8

The Abundance of Foods to Choose From

Start Now

31

Determining Individual Requirements

The Challenge of Choosing Foods 9

The Process of Change

Two Sets of Standards

31

How the Committee Establishes DRI Values—
An RDA Example 34

5

7

Can I Live on Just Supplements?

Scientific Challenge

4

Understanding the DRI

The Nation’s Nutrition Objectives

The Scientific Approach

2

Nutrition Tools—Standards
and Guidelines 30

2

Genetics, Nutrition, and Individuality

Meet the Nutrients

22

18

18

A CONSUMER’S GUIDE TO:
Reading Nutrition News 19
Food feature:
Nutrient Density:
How to Get
Enough Nutrients
without Too Many
Calories 20

45

46

A CONSUMER’S GUIDE TO: Controlling Portion
Sizes at Home and Away 48
The Last Word on Diet Planning

50

Checking Out Food Labels
What Food Labels Must Include

50
50

What Food Labels May Include

53

FOOD FEATURE: Getting a Feel for
the Nutrients in Foods 56
Norman Chan/Shutterstock.com

v

Self Check

59

CONTROVERSY 2: Are Some Foods Superfoods
for Health? 61

Chapter

3

The Remarkable Body
The Body’s Cells

67

68

Genes Control Functions

A Close Look at Carbohydrates
Sugars

105

Starch

107

Fibers

70

109

73

How Does the Nervous System Interact
with Nutrition? 74

Why Do Nutrition Experts Recommend
Fiber-Rich Foods? 111
Fiber Intakes and Excesses
Whole Grains

76

Why Do People Like Sugar, Salt, and Fat?

76

77

Microbes in the Digestive Tract

115

116

From Carbohydrates to Glucose

77

81

Why Do Some People Have Trouble Digesting Milk?

The Body’s Use of Glucose
Splitting Glucose for Energy

Absorption and Transport of Nutrients

Excess Glucose and Body Fatness

84

How Is Glucose Regulated in the Body?

The Glycemic Index of Food

91

126

127

129

What Happens If Blood Glucose Regulation
Fails? 131

Storage Systems 92
When I Eat More than My Body
Needs, What Happens to the Extra
Nutrients? 92

Diabetes

131

Hypoglycemia

131

Conclusion 132

92

Food feature: Finding the
Carbohydrates in Foods 132

Conclusion 92
94

Self Check
iStock.com/Floortje

CONTROVERSY 3:
Alcohol Use: Risks and
Benefits 95
vi

125

Think Fitness: What Can I Eat to Make
Workouts Easier? 129

A Letter from Your Digestive
Tract 86

Self Check

124

124

If “I Am What I Eat,” Then How Does a Peanut
Butter Sandwich Become “Me”? 83

Variations in Nutrient Stores

119

A CONSUMER’S GUIDE TO: Finding Whole-Grain
Foods 120

80

Are Some Food Combinations More Easily
Digested than Others? 82

The Excretory System

119

Digestion and Absorption of Carbohydrate

The Mechanical Aspect of Digestion
The Chemical Aspect of Digestion

109

If I Want to Lose Weight and Stay Healthy, Should I Avoid
Carbohydrates? 110

The Hormonal and Nervous Systems 73

The Digestive Tract Structures

108

The Need for Carbohydrates

What Do Hormones Have to Do with Nutrition?

105

109

Summary

The Body Fluids and the Circulatory
System 70

4

The Carbohydrates: Sugar,
Starch, Glycogen, and Fiber 104

Glycogen

69

Cells, Tissues, Organs, Systems

The Digestive System

Chapter

Contents

137

CONTROVERSY 4: Are Added Sugars
“Bad” for You? 139

Chapter

5

Milk and Milk Products
Grains

The Lipids: Fats, Oils,
Phospholipids, and
Sterols 144
Introducing the Lipids

How Are Fats Useful in Food?

A Close Look at Lipids

Self Check

147

Chapter

Saturated vs. Unsaturated Fatty Acids

149

Lipids in the Body

The Structure of Proteins

151

Amino Acids

152
152

Storing and Using the Body’s Fat

Recommendations for Lipid Intakes
Lipoproteins and Heart Disease Risk

Denaturation of Proteins

156

158

Protein Digestion

What Does Food Cholesterol Have to Do
with Blood Cholesterol? 159

Think Fitness: Why Exercise the Body
for the Health of the Heart? 160

The Roles of Body Proteins
The Fate of an Amino Acid

163

A CONSUMER’S GUIDE TO: Weighing Seafood’s
Risks and Benefits 164

The Effects of Processing on Unsaturated
Fats 165

167

200

How Much Protein Do People Need?

200

Nitrogen Balance

200

202

Protein Deficiency and Excess 204
166

What Happens When People Consume
Too Little Protein? 204
Is It Possible to Consume Too Much Protein?
Is a Gluten-Free Diet Best for Health?

Get to Know the Fats in Foods
Fats in Protein Foods

197

Food Protein: Need and Quality

Protein Quality

What Is “Hydrogenated Vegetable Oil,” and What’s
It Doing in My Chocolate Chip Cookies? 165

Fat in the Diet

196

A CONSUMER’S GUIDE TO: Evaluating Protein and
Amino Acid Supplements 198

162

What Are Trans-Fatty Acids, and Are They Harmful?

193

Providing Energy and Glucose

161

162

Requirements and Sources

190

The Importance of Protein 192

162

Omega-6 and Omega-3 Fatty Acid Families

189

What Happens to Amino Acids after Protein Is
Digested? 192

160

Why Do I Need Essential Fatty Acids?

186

Digestion and Absorption of Dietary
Protein 190

156

Essential Polyunsaturated Fatty Acids

168

167

185

Think Fitness: Can Eating Extra Protein Make
Muscles Grow Stronger? 189

154

Dietary Fat, Cholesterol, and Health

Omega-3 Fatty Acids

183

The Variety of Proteins

153

Recommendations Applied

183

How Do Amino Acids Build Proteins?

How Are Fats Digested and Absorbed?
Transport of Fats

6

The Proteins and Amino
Acids 182

148
148

176

CONTROVERSY 5: Is Butter Really
Back? The Lipid Guidelines Debate 178

Elena Schweitzer/Shutterstock.com

145

Triglycerides: Fatty Acids and Glycerol
Phospholipids and Sterols

170

FOOD FEATURE: Defensive
Dining 171

145

How Are Fats Useful to the Body?

169

205

206

FOOD FEATURE: Getting Enough but Not
Too Much Protein 207
Contents

vii

Self Check

211

The Roles of Vitamin C

Deficiency Symptoms and Intakes

CONTROVERSY 6: Are Vegetarian or
Meat-Containing Diets Better for
Health? 212

Chapter

7

Vitamin C Toxicity

Vitamin C Recommendations

Evgeny Karandaev/Shutterstock.com

218

Vitamin Precursors

Thiamin

Two Classes of Vitamins: Fat-Soluble and WaterSoluble 220

220

Roles of Vitamin A and Consequences of
Deficiency 222

Beta-Carotene

Folate

248

246

250
251

Biotin and Pantothenic Acid
Non–B Vitamins

Vitamin D 227
227

Self Check

228

Too Much Vitamin D—A Danger to Soft Tissues
Vitamin D from Sunlight

253

253

FOOD FEATURE: Choosing Foods Rich in
Vitamins 259

Too Little Vitamin D—A Danger to Bones

229

230

Vitamin D Intake Recommendations
Vitamin D Food Sources

262

CONTROVERSY 7: Vitamin Supplements: What are
the Benefits and Risks? 264

231

231

Chapter

8

Water and Minerals

Vitamin E 232
Roles of Vitamin E

232

Vitamin E Deficiency

232

Toxicity of Vitamin E

233

Water

Vitamin E Food Sources

233

234

274

Quenching Thirst and Balancing Losses

274
276

Drinking Water: Types, Safety, and Sources

235

Hard Water or Soft Water—Which Is Best?

235

Vitamin K Requirements and Sources

The Water-Soluble Vitamins

The Body’s Water Balance

273

A CONSUMER’S GUIDE TO: Liquid Calories 277

234

Vitamin K Deficiency

272

How Much Water Do I Need to Drink in a Day?

Vitamin K 234
Roles of Vitamin K

270

Why Is Water the Most Indispensable Nutrient?

Vitamin E Recommendations and U.S. Intakes

Water Safety and Sources

235

236

279

Body Fluids and Minerals

Think Fitness: Vitamins for Athletes

237

Water Follows Salt

Contents

280

281

Fluid and Electrolyte Balance

Vitamin C 237
viii

247

Vitamin B6

225

226

Vitamin K Toxicity

Niacin

Vitamin B12

224

Roles of Vitamin D

243

243

Riboflavin Roles

Vitamin A Recommendations and Sources

241

A CONSUMER’S GUIDE TO: The Effects of Food
Processing on Vitamins 244

221

Vitamin A Toxicity

240

241

The B Vitamins as Individuals

220

The Fat-Soluble Vitamins

The B Vitamins in Unison
B Vitamin Deficiencies

239

240

B Vitamin Roles in Metabolism

Definition and Classification of
Vitamins 219

239

239

Vitamin C Food Sources

The Vitamins

Vitamin A

237

281

279

279

Acid-Base Balance

282

The Major Minerals
Calcium

285

Magnesium

287

Sodium

Body Weight vs. Body Fatness
Using the Body Mass Index (BMI)

293

How Much Body Fat Is Ideal?

294

333

Think Fitness: Activity for a Healthy Body
Weight 335

302
303

How the Body Loses and Gains Weight

304

Other Trace Minerals and Some Candidates

The Body’s Response to Energy Deficit

304

338

Achieving and Maintaining a Healthy Body
Weight 340

310

CONTROVERSY 8 Osteoporosis: Can Lifestyle
Choices Reduce the Risk? 311

A CONSUMER’S GUIDE TO: Fad Diets

342

What Food Strategies Are Best for
Weight Loss? 344

9

Physical Activity Strategies

Energy Balance and
Healthy Body Weight
The Problems of Too Little or Too Much
Body Fat 318
What Are the Risks from
Underweight? 319
What Are the Risks from Too Much Body
Fat? 319
What Are the Risks from Central
Obesity? 320
How Fat Is Too Fat?

336

337

The Body’s Response to Energy Surplus

FOOD FEATURE: Meeting the Need for
Calcium 307

Chapter

332

Outside-the-Body Theories of Obesity

302

Self Check

330

Inside-the-Body Theories of Obesity

300

Copper

328

Satiation and Satiety—“Stop” Signals

Think Fitness: Exercise-Deficiency
Fatigue 297

Chromium

328

Hunger and Appetite—“Go” Signals

295

Fluoride

326

The Appetite and Its Control 328

294

Selenium

326

Measuring Body Composition and Fat
Distribution 326

293

The Trace Minerals

Zinc

325

The DRI Method of Estimating Energy
Requirements 325

292

Chloride

Iron

Estimated Energy Requirements (EER)

288

Potassium

Iodine

282

282

Phosphorus

Sulfate

How Many Calories Do I Need Each
Day? 323

What Strategies Are Best for Weight Gain?

317

Medical Treatment of Obesity
Obesity Medications
Obesity Surgery

Energy In and Energy Out

349

349
351

Once I’ve Changed My Weight,
How Can I Stay Changed? 352

Conclusion 353
FOOD FEATURE: Behavior Modification for
Weight Control 354
Self Check

323

348

349

Herbal Products and Gimmicks

321

The Body’s Energy Balance

347

322
George Nazmi Bebawi/Shutterstock.com

356

CONTROVERSY 9: The Perils of Eating
Disorders 358
Contents

ix

Chapter

10

Chapter

Performance
Nutrition 365

Nutrition and Chronic
Diseases 404

The Benefits of Fitness 366
The Nature of Fitness

366

Physical Activity Guidelines

368

The Essentials of Fitness

11

Causation of Chronic Diseases

405

Cardiovascular Diseases (CVD)

407

Atherosclerosis and Hypertension

369

Risk Factors for Cardiovascular Disease

How Do Muscles Adapt to Physical Activity?

Altayb/Getty Images

369

How Does Aerobic Training Benefit the Heart?

Think Fitness: Exercise Safety

371

Preventive Measures against CVD

372

Diabetes

The Muscles’ Energy Reservoir

How Does Type 2 Diabetes Develop?

The Aerobic Energy System

372

The Need for Food Energy

Cancer

374

379

Cancer Prevention

Fat Recommendations for Athletes   381
382

Vitamins and Minerals—Keys to Performance
Do Athletes Need Nutrient Supplements?

384

387

391

396

CONTROVERSY 10: Ergogenic Aids: Breakthroughs,
Gimmicks, or Dangers? 398
x

12

Food Safety and Food
Technology 440
Microbes and Food Safety

390

FOOD FEATURE: Choosing a Performance
Diet 392
Self Check

433

Chapter

386

A CONSUMER’S GUIDE TO: Selecting Sports
Drinks 389
Putting It All Together

428

CONTROVERSY 11: Nutritional Genomics: Can
It Deliver on Its Promises? 435

Fluids and Temperature Regulation in Physical
Activity 386
Fluid and Electrolyte Needs during Physical Activity

426

FOOD FEATURE: The DASH Diet: Preventive
Medicine 431
Self Check

384

385

Water Losses during Physical Activity

423

Conclusion 430

Protein Recommendations for Athletes   383

Other Beverages

423

Cancer Risk Factors

380

Protein for Building Muscles and for Fuel

Contents

421

A CONSUMER’S GUIDE TO: Deciding about
CAM 424

376

Carbohydrate Recommendations for Athletes

Iron—A Mineral of Concern

420

The Cancer Disease Process

375

Carbohydrate: Vital for Exercisers

419

Diabetes Prevention and Management

374

Fat as Fuel for Physical Activity

418

Harms from Diabetes

374

The Active Body’s Use of Fuels

413

Think Fitness: Ways to Include Physical
Activity in a Day 414

Three Energy Systems 372
The Anaerobic Energy System

407

442

How Do Microbes in Food Cause Illness in the
Body? 442
Food Safety from Farm to Plate

444

Safe Food Practices for Individuals

447

Which Foods Are Most Likely to Cause
Illness? 450

410

Protein Foods

451

Raw Produce

453

Other Foods

Teen Pregnancy

Think Fitness: Physical Activities for Pregnant
Women 497

454

Advances in Microbial Food Safety
Is Irradiation Safe?

456

Other Technologies

457

Natural Toxins in Foods

Why Do Some Women Crave Pickles and Ice Cream While
Others Can’t Keep Anything Down? 497

456

Some Cautions for Pregnant Women

Toxins, Residues, and Contaminants in Foods
Pesticides

458

458

Alcohol’s Effects

Animal Drugs—What Are the Risks?
Environmental Contaminants

Diabetes

464

Are Food Additives Safe?

466

Regulations Governing Additives

Additives to Improve Safety and Quality

Hypertension

503

Preeclampsia

503

503
503

When Should a Woman Not Breastfeed?

Fat Replacers and Artificial Fats

471

Feeding the Infant

471

Nutrient Needs

FOOD FEATURE: Handling Real-Life Challenges
to Food Safety 472

506

Formula Feeding

507

510

A CONSUMER’S GUIDE TO: Formula Advertising
versus Breastfeeding Advocacy 511

475

CONTROVERSY 12: Genetically Engineered Foods:
What Are the Pros and Cons? 477

505

506

Why Is Breast Milk So Good for Babies?

Conclusion 472

Chapter

502

Nutrition during Lactation

468

468

Incidental Food Additives

501

502

Lactation

466

500

501

Troubleshooting

463

498

500

Experts’ Advice

A CONSUMER’S GUIDE TO: Understanding
Organic Foods 461

Self Check

Drinking during Pregnancy
Fetal Alcohol Syndrome

458

Flavoring Agents

496

An Infant’s First Solid Foods
Looking Ahead

512

515

FOOD FEATURE: Mealtimes with Infants

13

Self Check

Life Cycle Nutrition: Mother
and Infant 484
Pregnancy: The Impact of Nutrition on the
Future 485
Preparing for Pregnancy

485

The Events of Pregnancy

487

Increased Need for Nutrients
Food Assistance Programs

517

CONTROVERSY 13: Childhood Obesity and Early
Chronic Diseases 519

Chapter

14

Child, Teen, and Older
Adult 526

489

Early and Middle Childhood

494

Feeding a Healthy Young Child

How Much Weight Should a Woman
Gain during Pregnancy? 494
Weight Loss after Pregnancy

Mealtimes and Snacking

527
527

531

How Do Nutrient Deficiencies
Affect a Child’s Brain? 534

495

Should Pregnant Women Be Physically
Active? 496

516

Tim UR/Shutterstock.com

The Problem of Lead
Contents

535

xi

The Malnutrition of Extreme
Poverty 574

Food Allergies, Intolerances, and Aversions 537
Can Diet Make a Child Hyperactive?
Dental Caries

539

540

Hidden Hunger—Vitamin and Mineral
Deficiencies 574

Is Breakfast Really the Most Important Meal of the
Day for Children? 540

Two Faces of Childhood Malnutrition

How Nourishing Are the Meals Served at
School? 541

Medical Nutrition Therapy

576

Nutrition in Adolescence 543

The Future Food Supply
and the Environment 576

Nutrient Needs

Threats to the Food Supply

543

Common Concerns

545

Eating Patterns and Nutrient Intakes

The Later Years

545

Olyina/Shutterstock.com

546

A CONSUMER’S GUIDE TO: Nutrition for PMS
Relief 547

Nutrition in the Later Years

548

Energy, Activity, and the Muscles

548

Protein Needs

Fats and Arthritis
Vitamin Needs

552

Conclusion

581

581

584

A Chemical Structures: Carbohydrates,

555

Lipids, and Amino Acids
555

Guidelines

Management

CONTROVERSY 14: Nutrient–Drug Interactions:
Who Should Be Concerned? 562

Guidelines for Americans

Requirements

568
568
570

Glossary
Index

572
Contents

E-1

F Notes F-1
G Answers to Chapter Questions G-1
H Physical Activity Levels and Energy

Hunger and the Future of
Food 567

World Poverty and Hunger

D-1

E Eating Patterns to Meet the Dietary

15

What U.S. Food Programs Address Low Food Security?

B-1

C Aids to Calculations C-1
D Food Lists for Diabetes and Weight

560

Food Poverty in the United States

A-1

B World Health Organization

556

FOOD FEATURE: Single Survival and Nutrition
on the Run 558

xii

581

Appendixes
554

Can Diet Affect the Course of Alzheimer’s Disease?

U.S. Food Insecurity

581

581

CONTROVERSY 15: How Can We Feed Ourselves
Sustainably? 585

Aging, Immunity, and Inflammation

Chapter

Individuals

Self Check

551

Food Choices of Older Adults

580

A CONSUMER’S GUIDE TO: Making “Green”
Choices (Without Getting “Greenwashed”) 582

550

Can Diet Choices Lengthen Life?

Self Check

580

Food and Nutrition Professionals

551

Water and the Minerals

How Can People Help?

Educators and Students

Think Fitness: Benefits of Physical Activity
for the Older Adult 550
Carbohydrates and Fiber

578

Private and Community Enterprises

549

576

Fisheries and Food Waste

Government Action

574

GL-1

IN-1

H-1

Dietary Reference Intakes and Other Standards
(at the back of the book)

Estimated Energy Requirements (EER);
Recommended Dietary Allowances
(RDA) and Adequate Intakes (AI) for
Water and the Energy Nutrients
Recommended Dietary Allowances
(RDA) and Adequate intakes (AI) for
Vitamins
Recommended Dietary Allowances
(RDA) and Adequate intakes (AI) for
Minerals
Tolerable Upper Intake Levels (UL) for
Vitamins
Tolerable Upper Intake Levels (UL) for
Minerals
Daily Values for Food Labels
Glossary of Nutrient Measures
Body Mass Index (BMI) for Adults
Body Mass Index-for-Age Percentiles:
Boys and Girls, Age 2 to 20

A

B

B

C
C
D
D
E
E

Contents

xiii

Preface
A

billboard in Louisiana reads, “Come as you are. Leave different,” meaning that once you’ve seen, smelled, tasted,
and listened to Louisiana, you’ll never be the same. This book
extends the same invitation to its readers: come to nutrition
science as you are, with all of the knowledge and enthusiasm
you possess, with all of your unanswered questions and misconceptions, and with the habits and preferences that now dictate what you eat.
But leave different. Take with you from this study a more
complete understanding of nutrition science. Take a greater
ability to discern between nutrition truth and fiction, to ask
sophisticated questions, and to find the answers. Finally, take
with you a better sense of how to feed yourself in ways that not
only please you and soothe your spirit but nourish your body
as well.
For more than four decades, Nutrition: Concepts and Controversies has been a cornerstone of nutrition classes across North
America, serving the needs of students and professors. In keeping with our tradition, in this, our 15th edition, we continue
exploring the ever-changing frontier of nutrition science, confronting its mysteries through its scientific roots. We maintain
our sense of personal connection with instructors and learners alike, writing for them in the clear, informal style that has
become our trademark.

Pedagogical Features
Throughout these chapters, features tickle the reader’s interest and inform. For both verbal and visual learners, our logical presentation and our lively figures keep interest high and
understanding at a peak. The photos that adorn many of our
pages add pleasure to reading.
Many tried-and-true features return in this edition: Each
chapter begins with What Do You Think? questions to pique
interest. What Did You Decide? at the chapter’s end asks readers
to draw conclusions. A list of Learning Objectives (LO) offers a
preview of the chapter’s major goals, and the LO
reappear under section headings to make
clear the main take-away messages. Do
the Math margin features challenge
readers to solve nutrition problems,
with examples provided. Think Fitness
reminders alert readers to links among
nutrition, ­
fitness, and health. Food Feature sections act as bridges between theory
and practice; they are practical applications
of the chapter concepts. The consumer
sections, entitled A Consumer’s Guide To .
. ., lead readers through an often bewildering marketplace with scientific clarity, preparing them to move ahead with sound marketplace

decisions. Each Consumer’s Guide ends with review questions
to improve recall of the main points.
By popular demand, we have retained our Snapshots of vitamins and minerals, which now reflect the 2015 Daily Values. These
concentrated capsules of information depict food sources of vitamins and minerals, present DRI values, and offer the chief functions
of each nutrient along with deficiency and ­toxicity symptoms.
New or major terms are defined in the margins of chapter
pages or in nearby tables, and they also appear in the Glossary
at the end of the book. Terms defined in margins are printed in
blue boldface type; terms in tables are in black. Readers who
wish to locate any term can quickly do so by consulting the
Index, which lists the page numbers of definitions in boldface
type. Each chapter closes with the indispensible Self Check that
provides study questions, with answers in Appendix G to provide
immediate feedback to the learner.

Controversies
The Controversies of this book’s title invite you to explore
beyond the safe boundaries of established nutrition knowledge.
These optional readings, which appear at the end of each
chapter, delve into current research themes and ongoing
debates among nutrition scientists. These fast-changing topics
capture interest and demonstrate how scientific investigations
both build nutrition knowledge and challenge it.

Chapter Contents

Chapter 1 begins the text with a personal challenge to students. It asks the question so many people ask of nutrition
­educators—“Why should people care about nutrition?” We
answer with a lesson in the ways in which nutritious foods
affect diseases and present a continuum of diseases from purely
genetic in origin to those almost totally preventable by nutrition. After presenting some beginning facts about the genes,
nutrients, bioactive food components, and nature of foods,
the chapter goes on to present the Healthy People goals for the
nation. It concludes with a discussion of scientific research
and quackery.
Chapter 2 brings together the concepts of
nutrient standards, such as the Dietary Reference Intakes, and diet planning using the
Dietary Guidelines for Americans
2015–2020. Chapter 3 presents a
thorough, but brief, introduction to
the workings of the human body from
the genes to the organs, with major
emphasis on the digestive system and
its microbiota. Chapters 4 through 6 are
devoted to the energy-yielding nutrients:
carbohydrates, lipids, and protein. ControJacek Chabraszewski/Shutterstock.com
versy 4 has renewed its focus on theories and

xiv

fables surrounding the health effects of added sugars in the
diet. Controversy 5 considers the scientific underpinnings of
lipid guidelines.
Chapters 7 and 8 present the vitamins, minerals, and water.
Chapter 9 relates energy balance to body composition, obesity,
and underweight and provides guidance on lifelong weight
maintenance. Chapter 10 presents the relationships among
physical activity, athletic performance, and nutrition, with
some guidance about products marketed to athletes. Chapter 11
applies the essence of the first 10 chapters to chronic disease
development and prevention.
Chapter 12 delivers urgently important concepts of food
safety and ends with practical pointers for applying them in
real-life situations. It also addresses the usefulness and safety
of food additives, including artificial sweeteners and artificial
fats. Chapters 13 and 14 emphasize the importance of nutrition
through the life span, with issues surrounding childhood obesity in Controversy 13. Chapter 14 includes nutrition advice for
feeding preschoolers, schoolchildren, teens, and the elderly.
Chapter 15 devotes attention to hunger and malnutrition,
both in the United States and throughout the world. It also
touches on the vast network of problems that threaten the
future food supply, and explores potential paths to solutions.

●●

●●

●●

Controversy definitions and descriptions follow Academy
of Nutrition and Dietetics,
Definition of Terms List (2017).
Updated NDTR credentials.

Chapter 2
Updated U.S. diet compared with ideals figure.
Defined term nutritional equivalents.
Major revision to diet planning section and tables.
Expanded and clarified Food Lists for Weight Management
coverage.
New food label comparison figure.
Improved phytochemical tables.
Moved Table C2–3 to instructors’ materials.

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Chapter 3
Reorganized chapter for greater focus on digestive tract
and functions. Moved other body systems to instructors’
materials.
Revamped figure of pH values.
Reorganized figure of small intestinal lining.
Introduced and defined term microbiome.
Reorganize table of foods and intestinal gas.
Major reorganization, update, and streamlining of the
alcohol Controversy.

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Our Message to You
Our purpose in writing this text, as always, is to enhance our
readers’ understanding of nutrition science. We also hope the
information on this book’s pages will reach beyond the classroom
into our readers’ lives. Take the information you find inside this
book home with you. Use it in your life: nourish yourself, educate
your loved ones, and nurture others to be healthy. Stay up with
the news, too—for despite all the conflicting messages, inflated
claims, and even quackery that abound in the marketplace, true
nutrition knowledge progresses with a genuine scientific spirit,
and important new truths are constantly unfolding.

Chapter 4
New explanation of energy nutrients percentages in relation to total calorie intake.
New figure of percentages of energy nutrients.
Moved figure of fiber composition to instructors’ materials.
New figure of strategies to increase fiber intake.
Shortened glycemic index coverage.
Major diabetes coverage moved to Chapter 11.
New section on diabetes and hypoglycemia, explaining
failure of blood glucose control.
New section on sugar alcohols.
New sugar alcohol table.
Controversy is streamlined and updated.

●●

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●●

●●

New to This Edition
Every section of each chapter of this text reflects the changes in
nutrition science occurring since the last edition. The changes
range from subtle shifts of emphasis to entirely new sections
that demand our attention. Appendix F supplies current references; older references may be viewed in previous editions,
available from the publisher.
Inside Front Cover Pages
The DRI tables, previously located on the inside front cover
pages, have joined other standards at the back of the book,
pages A through C.

●●

●●

●●

Chapter 5
Defined term shortening.
Defined term inflammation.
Updated and improved coverage of EPA and DHA.
Moved figure of fish oil supplement label to instructors’
materials.
New bar graph figure of lipids in grain foods.
Updated Controversy.

●●

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●●

Chapter 6
Added bone broth discussion to Consumer’s Guide.
Removed adult bone loss from protein excess.
New figure comparing energy and protein in Greek-style
yogurt and a commercial highprotein shake.
Condensed and combined tables in Controversy section.
New sample 2,000-calorie menu for a day of vegetarian
meals.

●●

Chapter 1
Updated leading causes of death figure.
Updated midcourse review of HP2020.
Defined term macronutrients and micronutrients.
Defined term meta-analysis.

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Preface

xv

Chapter 7
Fully updated each vitamin section.
Converted photos to figures, as follows: Vitamin E in Oils;
Vitamin K for newborns; Folate and neural tube defects.
Moved table of Vitamin D in disease to instructors’ materials.
New Consumer’s Guide on food processing and vitamins.
New figure of the effect of folic acid fortification on neural
tube defect prevalence in selected countries of the world.
Updated Controversy section; addressed current supplement contamination concerns.
New figure of how to read a food label.

●●

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New table of chronic disease risk factors.
New table of adult blood pressure standards.
New major section on diabetes; new table of misconceptions about diabetes.
Introduced term precision medicine.
Addressed consumer privacy in genetic testing.

●●

●●

●●

Chapter 8
Reorganized, updated water section.
Reorganized sodium sections.
Replaced figure of sodium sources.
New figure of sodium on a food label.
Created new figures from photos as follows: Osmosis (eggplant); goiter; iodized salt label; nonheme iron absorption;
zinc deficiency.
New figure of average daily sodium intakes in U.S. adults.
New photo of calcium sources.
Moved section on tracking calcium to instructors’ materials.
Updated Controversy.

●●

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Chapter 9
New obesity maps reflecting newer analytical methods.
Defined clinical term adiposity-based chronic disease.
Added sleep function of ghrelin.
Refined section on microbiome and obesity.
Addressed efficacy of artificial sweeteners.
Added discussion of genetic alterations in obesity.
New summary figure of factors in obesity development.
Added sleeve gastrectomy to surgical options.
New explanation of intermittent fasting.
Defined term exergaming.
Addressed cultural differences in dietary energy density.
Updated terminology associated with female athlete triad.
New table of harms from anorexia nervosa.

Chapter 12
Defined terms pathogen, intoxication, and endemic.
Added term toxin-mediated infections.
New section on the FDA Food Safety Modernization Act,
with definition.
Expanded coverage of package dating.
Defined FDA’s new Produce Safety Rule.
Moved kitchen test table to new Food Feature.
Restructured thermometer and safe temperature figures
for clarity.
New Food Feature: Handling Real-Life Challenges to Food
Safety.
New figure on selective breeding.
Defined gene editing and CRISPR technology.
Described and added new figure of genetically engineered
salmon.
Added consumer concerns about glyphosate to summary
table.

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Chapter 13
Deleted the infant mortality figure.
Replaced the spina bifida figure.
Added a new table of seafood advice for pregnant and lactating women.
Replaced the sketched figure of facial characteristics of
FAS with photo of FAS child.
Reorganized table of supplements for breastfed infants.
Added a discussion and definition of responsive feeding.
Added hunger and satiety signals to the table of infant
development.
New table of parental strategies against childhood obesity.
New adequate sleep section and table.

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Chapter 10
Reorganized several major sections.
Addressed energy availability and energy need concepts.
Addressed gastrointestinal effects of ultraendurance events.
New carbohydrate and protein recommendations from the
Academy of Nutrition and Dietetics (AND).
New figure of anemia in female athletes.
New hydration schedule from AND.
Applied guidelines for nutrient timing from the International Society of Sports Nutrition.
New discussion of beetroot and dietary nitrite among
ergogenic aids.

●●

Chapter 14
Updated MyPlate figure.
Updated and improved allergy section.
Condensed and updated PMS coverage.
New section on weight loss and overweight in aging.
Restructured, updated vitamin D section.
Addressed the Mediterranean Eating Pattern in Alzheimer’s disease development.
New figure of controllable factors associated with dementia in aging.
New figure of caffeine sources.

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Chapter 11
Complete chapter reorganization to focus on nutrition and
chronic diseases.
Removed discussion of infectious disease.

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xvi

Preface

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Chapter 15
New figure of trends in prevalence of food insecurity.
Updated hunger sections.
Several new figures.

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Appendix Changes:
Deleted the Table of Food Composition.
Previous Appendix I, Chemical Structures, is now Appendix A.

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Ancillary Materials
Students and instructors alike will appreciate the innovative
teaching and learning materials that accompany this text.
MindTap: A new approach to highly personalized online
learning. Beyond an eBook, homework solution, digital supplement, or premium website, MindTap is a digital learning platform that works alongside your campus LMS to deliver course
curriculum across the range of electronic devices in your life.
MindTap is built on an “app” model allowing enhanced digital
collaboration and delivery of engaging content across a spectrum of Cengage and non-Cengage resources.
Instructor Companion Site: Everything you need for your
course in one place! This collection of book-specific lecture and
class tools is available online via www.­cengage.com/login. ­Access
and download PowerPoint presentations, images, instructors’
manual, videos, and more.
Test Bank with Cognero: Cengage Learning Testing Powered by Cognero is a flexible online system that allows you to:
Author, edit, and manage test bank content from multiple
Cengage Learning solutions.
Create multiple test versions in an instant.
Deliver tests from your LMS, your classroom, or wherever
you want.

●●

●●

●●

Diet & Wellness Plus: Diet & Wellness Plus helps you understand how nutrition relates to your personal health goals.
Track your diet and activity, generate reports, and analyze
the nutritional value of the food you eat. Diet & Wellness Plus
includes over 75,000 foods as well as custom food and recipe
features. The new Behavior Change Planner helps you identify
risks in your life and guides you through the key steps to make
positive changes. Diet & Wellness Plus is also available as an
app that can be accessed from the app dock in MindTap.
Global Nutrition Watch: Bring currency to the classroom
with Global Nutrition Watch from Cengage Learning. This
user-friendly website provides convenient access to thousands of trusted sources, including academic journals, newspapers, videos, and podcasts, for you to use for research
projects or classroom discussion. Global Nutrition Watch
is updated daily to offer the most current news about topics
­r elated to nutrition.

Acknowledgments

●●

Linda DeBruyne, M.S., R.D.N. (Chapters 11 and 13). Linda
received her master’s degree in nutrition from Florida
State University and is a founding member of Nutrition
and Health Associates. She also coauthors the college
nutrition texts Nutrition and Diet Therapy and Nutrition for
Health and Health Care.
Shannon Dooies Gower-Winter, M.S., R.D.N./L.D.N.
(Chapter 7). Shannon graduated from Florida State University with her master’s degree in nutrition. She has taught
nutrition at Florida State University and lectured on topics
related to childhood nutrition throughout the state. She
has conducted research in the area of nutritional neuroscience, where her work focused on various roles of zinc in
the brain. Her research has been presented at regional and
national scientific conferences, and she has coauthored
multiple articles in peer-reviewed journals.

Our special thanks to our publishing team—Miriam Myers,
Lori Hazzard, and Carol Samet—for their superb work and dedication to excellence.
We would also like to thank MPS North America LLC
for their work on the student and instructor ancillaries for the
15th edition, which includes the test bank, instructors’ manual, and PowerLecture.

Reviewers of Recent Editions
As always, we are grateful for the instructors who took the
time to comment on this revision. Your suggestions were
invaluable in strengthening the book and suggesting new lines
of thought. We hope you will continue to provide your comments and suggestions.
Samuel Adeyeye, Georgia Southern University
Katherine Alaimo, Michigan State University
Linda Armstrong, Normandale Community College
Tammy Lee Christensen, Hostos Community College (CUNY)
Dorinda M. Cosimano, Kean University
Katie Ferraro, Santa Rosa Junior College
Shoshana Freedman, Glendale Community College
Keith R. Hench, Ph.D., Kirkwood Community College
Rachel K. Johnson, University of Vermont
Lauren Lavretsky, University of Texas at El Paso
David Lightsey, M.S., Bakersfield College
Cheryl McAfee, RDN, LD, Prince George’s Community College
Letty Moreno-Brown, El Paso Community College/University of
Texas, El Paso
Molly Ranney, Finger Lakes Community College
Victoria Rethmeier, Southeast Community College
Laura Rokosz, EGGLROCK Nutrition, LLC
Laurie Runk, Coastline Community College
Christie Shubert, University of North Florida
Taylor C. Wallace, George Mason University

Our thanks to our partners Linda Kelly DeBruyne and Sharon
Rolfes for decades of support. Thank you, David Warren Cox for
generating our orderly endnote lists.
We are also grateful to the nutrition professionals who
updated sections of this edition.
Preface

xvii

fcafotodigital/Getty Images

1

Food Choices and Human Health

Learning Objectives

After reading this chapter, you should
be able to accomplish the following:

LO 1.1

Describe the ways in which food choices impact a
person’s health.

LO 1.2

List the seven major categories of nutrition and
weight-related objectives included in the publication Healthy People 2020.

LO 1.3

Name the six classes of nutrients.

LO 1.4

Give examples of the challenges and solutions
to choosing a health-promoting diet.

LO 1.5

Describe the science of nutrition.

LO 1.6

Describe the characteristics of the six stages
of behavior change.

LO 1.7

Explain how the concept of nutrient density can
facilitate diet planning.

LO 1.8

Evaluate the authenticity of any given nutrition
information source.

What do you think?
Can your diet make a real difference between
getting sick or staying healthy?
Are supplements more powerful than food for
ensuring good nutrition?

What makes your favorite foods your favorites?
Are news and media nutrition reports informative
or confusing?

Jack Frog/Shutterstock.com

I

When you choose foods with nutrition in
mind, you can enhance your own well-being.

f you care about your body, and if you have strong feelings about food, then you
have much to gain from learning about nutrition—the science of how food nourishes the body. Nutrition is a fascinating, much-talked-about subject. Each day, newspapers, Internet websites, radio, and television present stories of new findings on
nutrition and heart health or nutrition and cancer prevention, and at the same time,
advertisements and commercials bombard us with multicolored pictures of tempting foods—pizza, burgers, cakes, and chips. If you are like most people, when you eat
you sometimes wonder, “Is this food good for me?” or you berate yourself, “I probably
shouldn’t be eating this.”
When you study nutrition, you learn which foods serve you best, and you can work
out ways of choosing foods, planning meals, and designing your diet wisely. Knowing
the facts can enhance your health and your enjoyment of eating while relieving your
feelings of guilt or worry that you aren’t eating well.
This chapter addresses these “why,” “what,” and “how” questions about nutrition:
▪▪

Why care about nutrition? Why be concerned about the nutrients in your foods?
Why not just take supplements?

▪▪

What are the nutrients in foods, and what roles do they play in the body? What
are the differences between vitamins and minerals?

▪▪

What constitutes a nutritious diet? How can you choose foods wisely, for nutrition’s sake? What factors motivate your choices?

▪▪

How do we know what we know about nutrition? How does nutrition science
work, and how can a person keep up with changing information?

Controversy 1 concludes the chapter by offering ways to distinguish between trustworthy sources of nutrition information and those that are less reliable.

A Lifetime of Nourishment
LO 1.1

food scientifically, materials, usually of plant or
animal origin, that contain essential nutrients, such as carbohydrates, fats, proteins,
vitamins, or minerals, and that are ingested and
assimilated by an organism to produce energy,
stimulate growth, and maintain life; socially, a
more limited number of such materials defined
as acceptable by a culture.

nutrition the study of the nutrients in foods and
in the body; sometimes also the study of human
behaviors related to food.
diet the foods (including beverages) a person
usually eats and drinks.
nutrients components of food that are indispensable to the body’s functioning. They provide
energy, serve as building material, help maintain
or repair body parts, and support growth. The
nutrients include water, carbohydrate, fat, protein, vitamins, and minerals.
malnutrition any condition caused by excess
or deficient food energy or nutrient intake or by
an imbalance of nutrients. Nutrient or energy
deficiencies are forms of undernutrition; nutrient
or energy excesses are forms of overnutrition.

2

Describe the ways in which food choices impact a person’s health.

If you live for 65 years or longer, you will have consumed more than 70,000 meals, and
your remarkable body will have disposed of 50 tons of food. The foods you choose exert
cumulative effects on your body.1* As you age, you will see and feel those effects—if you
know what to look for.
Your body renews its structures continuously. Each day, it builds a little muscle,
bone, skin, and blood, replacing old tissues with new. It may also add a little fat if you
consume excess food energy (calories) or subtract a little if you consume less than you
require. Some of the food you eat today becomes part of “you” tomorrow.
The best food for you, then, is the kind that supports the growth and maintenance
of strong muscles, sound bones, healthy skin, and sufficient blood to cleanse and nourish all parts of your body. This means you need food that provides not only the right
amount of energy but also sufficient nutrients—that is, enough water, carbohydrates,
fats, protein, vitamins, and minerals. If the foods you eat provide too little or too much
of any nutrient today, your health may suffer just a little today. If the foods you eat provide too little or too much of one or more nutrients every day for years, then in later life
you may suffer severe disease effects.
A well-chosen diet supplies enough energy and enough of each nutrient to prevent
malnutrition. Malnutrition includes deficiencies, imbalances, and excesses of nutrients, alone or in combination, any of which can take a toll on health over time.
Key Points
▪▪ The nutrients in food support growth, maintenance, and repair of the body.
▪▪ Deficiencies, excesses, and imbalances of energy and nutrients bring on the
diseases of malnutrition.
*Reference notes are in Appendix F.

Chapter 1 Food Choices and Human Health

Table 1–1

Leading Causes of Death in the United States
Chronic diseases cause the great majority of deaths among U.S. adults
and account for more than 85 percent of U.S. health-care costs.
Percentage of Total Deaths

1. Heart disease

23.5

2. Cancers

22.5

3. Chronic lung disease

5.7

4. Strokes

5.0

5. Accidents

5.0

6. Alzheimer’s disease

3.3

7. Diabetes mellitus

2.9

8. Pneumonia and influenza

2.2

9. Kidney disease

1.8

10. Suicide

1.6

Note: The diseases highlighted in bold have relationships with diet.
Sources: National Center for Chronic Disease Prevention and Health Promotion, Chronic disease prevention and
health promotion, www.cdc.gov/chronicdisease, 2017, updated regularly; J. Q. Xu and coauthors, Deaths: Final
data for 2013, National Vital Statistics Reports 64 (Hyattsville, MD: National Center for Health Statistics, 2016).

The Diet–Health Connection
Your choice of diet profoundly affects your health, both today and in the future. Among
the common lifestyle habits that profoundly affect development of these diseases, only
two are more influential than food habits: smoking and using other forms of tobacco
and drinking alcohol in excess. Of the leading causes of death listed in Table 1–1, four—
heart disease, cancers, strokes, and diabetes—are directly related to nutrition, and
another—accidents—is related to drinking alcohol.
Many older people suffer from debilitating conditions that could have been largely
prevented had they applied the nutrition principles known today. The chronic
diseases—heart disease, diabetes, some kinds of cancer, dental disease, and adult
bone loss—all have a connection to poor diet. These diseases cannot be prevented
by a good diet alone; they are to some extent determined by a person’s genetic constitution, activities, and lifestyle. Within the range set by your genetic inheritance,
however, the likelihood of developing these diseases is strongly influenced by your
daily choices.
Key Point
▪▪ Nutrition profoundly affects health.

Genetics, Nutrition, and Individuality

chronic diseases degenerative conditions
or illnesses that progress slowly are long in
duration, and lack an immediate cure. Chronic
diseases limit functioning, productivity, and the
quality and length of life. Examples include heart
disease, cancer, and diabetes.

Figure 1–1 demonstrates that genetics and nutrition affect different diseases to varying degrees. The anemia caused by sickle-cell disease, for example, is purely hereditary
and thus appears at the left of Figure 1–1 as a genetic condition largely unrelated to
nutrition. Nothing a person eats affects the person’s chances of contracting this anemia,
although nutrition therapy may help ease its course. At the other end of the spectrum,
iron-deficiency anemia most often results from undernutrition. Diseases and conditions
of poor health appear all along this continuum, from almost entirely genetically based

anemia a blood condition in which red blood
cells, the body’s oxygen carriers, are inadequate
or impaired and so cannot meet the oxygen
demands of the body.

A Lifetime of Nourishment

3

Figure 1–1

Nutrition and Disease
Not all diseases are equally influenced by diet. Some, such as sickle-cell anemia, are almost purely genetic. Some,
such as diabetes, may be inherited (or the tendency to develop them may be inherited in the genes) but may be influenced by diet. Some, such as vitamin-deficiency diseases, are purely dietary.
Less
nutritionrelated

Down syndrome
Hemophilia
Sickle-cell anemia

genome (GEE-nome) the full complement of
genetic information in the chromosomes of a
cell. In human beings, the genome consists of
about 35,000 genes and supporting materials.
The study of genomes is genomics. Also defined
in Controversy 11.
genes units of a cell’s inheritance; sections
of the larger genetic molecule DNA (deoxyribonucleic acid). Each gene directs the making of
one or more of the body’s proteins.

DNA an abbreviation for deoxyribonucleic
(dee-OX-ee-RYE-bow-nu-CLAY-ick) acid, the
thread-like molecule that encodes genetic
information in its structure; DNA strands coil
up densely to form the chromosomes (Chapter 3
provides more details).

Think Fitness
Why should people bother to be
physically active? A person’s daily food
choices can powerfully affect health, but
the combination of nutrition and physical
activity is more powerful still. People who
combine regular physical activity with a
nutritious diet can expect to receive at
least some of these benefits:
◾◾

Reduced risks of cardiovascular
diseases, diabetes, certain cancers,
hypertension, and other diseases.

◾◾

◾◾

◾◾
◾◾

4

Adult bone loss
(osteoporosis)
Cancer
Infectious diseases

Diabetes
Hypertension
Heart disease

Iron-deficiency
anemia
Vitamin deficiencies
Mineral deficiencies
Toxicities
Poor resistance to
disease

More
nutritionrelated

to purely nutritional in origin; the more nutrition-related a disease or health condition
is, the more successfully sound nutrition can prevent it.
Furthermore, some diseases, such as heart disease and cancer, are not one disease
but many. Two people may both have heart disease but not the same form; one person’s cancer may be nutrition-related, but another’s may not be. Individual people differ
genetically from each other in thousands of subtle ways, so no simple statement can
be made about the extent to which diet can help any one person avoid such diseases or
slow their progress.
The identification of the human genome establishes the entire sequence of the
genes in human DNA. This work has, in essence, revealed the body’s instructions for
making all of the working parts of a human being. The human genome is 99.9 percent
the same in all people; all of the normal variations such as differences in hair color, as
well as variations that result in diseases such as sickle-cell anemia, lie in the 0.1 percent
of the genome that varies. Nutrition scientists are working industriously to apply this

Why Be Physically Active?
◾◾

Feeling of belonging—the companionship of sports.

◾◾

Stronger self-image.

◾◾

Reduced body fat and increased lean
tissue.

◾◾

A more youthful appearance,
healthy skin, and improved
muscle tone.

◾◾

Greater bone density and lessened
risk of adult bone loss in later life.

Increased endurance, strength, and
flexibility.

◾◾

Increased independence in the
elderly.

More cheerful outlook and less likelihood of depression.

◾◾

Sound, beneficial sleep.

◾◾

Faster wound healing.

Improved mental functioning.

◾◾

Reduced menstrual symptoms.

Feeling of vigor.

◾◾

Improved resistance to infection.

If even half of these benefits were yours
for the asking, wouldn’t you step up to
claim them? In truth, they are yours to
claim, at the price of including physical
activity in your day. Chapter 10 explores
the topics of fitness and physical
activity.

start now! Ready to make a
change? Go to this book’s website at
www.cengage.com, access MindTap,
and open the Diet & Wellness
Plus program. Track your physical
activities—all of them—for three
days. After you have recorded your
activities, see how much time you spent
exercising at a moderate to vigorous
level. Should you increase the intensity
level and amount of your activity?

Chapter 1 Food Choices and Human Health

new wealth of knowledge to benefit human health. Later chapters expand on the emerging story of nutrition and the genes.
Key Points
▪▪ Diet influences long-term health within the range set by genetic inheritance.
▪▪ Nutrition exerts little influence on some diseases but strongly affects others.

Other Lifestyle Choices
Besides food choices, other lifestyle choices affect people’s health. Tobacco use and
alcohol and other substance abuse can destroy health. Physical activity, sleep, emotional
stress, and other environmental factors can also modify the severity of some diseases.
Physical activity is so closely linked with nutrition in supporting health that most
chapters of this book offer a feature called Think Fitness, such as the previous one.
Key Point
▪▪ Life choices, such as being physically active or using tobacco or alcohol, can
improve or damage health.

The Nation’s Nutrition Objectives
List the seven major categories of nutrition and weight-related objectives
included in the publication Healthy People 2020.

The U.S. Department of Health and Human Services has set specific 10-year objectives
to guide national health promotion efforts.2 The vision of its Healthy People 2020 is a
society in which all people live long, healthy lives. Table 1–2 (p. 6) provides a quick
scan of the nutrition and weight-related objectives set for this decade. The inclusion of
nutrition and food-safety objectives shows that public health officials consider these
areas to be top national priorities.
In 2015, the nation’s health report was mixed: more adults reported spending the
recommended amount of leisure time in physical activity; at the same time, most people’s diets still lacked vegetables, and obesity rates were creeping higher.3 To fully meet
the Healthy People nutrition goals, our nation must change its eating habits.
The next section shifts focus to the nutrients at the core of nutrition science. As your
course of study progresses, the individual nutrients will become like old friends, revealing more and more about themselves as you move through the chapters.
Key Point
▪▪ Each decade, the U.S. Department of Health and Human Services sets health and
nutrition objectives for the nation.

The Human Body and Its Food
LO 1.3

Steve Debenport/Getty Images

LO 1.2

The aim of Healthy People 2020 is to help
people live long, healthy lives.

Name the six classes of nutrients.

As your body moves and works each day, it must use energy. The energy that fuels
the body’s work comes indirectly from the sun by way of plants. Plants capture
and store the sun’s energy in their tissues as they grow. When you eat plant-derived
foods such as fruit, grains, or vegetables, you obtain and use the solar energy they have
stored. Plant-eating animals obtain their energy in the same way, so when you eat animal tissues, you are eating compounds containing energy that came originally from
the sun.
The body requires six kinds of nutrients—families of molecules indispensable to its
functioning—and foods deliver these. Table 1–3 (p. 6) lists the six classes of nutrients. Four
of these six are organic; that is, the nutrients contain the element carbon derived from
living things.

organic carbon containing. Four of the six
classes of nutrients are organic: carbohydrate,
fat, protein, and vitamins. Organic compounds
include only those made by living things and do
not include compounds such as carbon dioxide,
diamonds, and a few carbon salts.

The Human Body and Its Food

5

energy the capacity to do work. The energy in
food is chemical energy; it can be converted to
mechanical, electrical, thermal, or other forms of
energy in the body. Food energy is measured in
calories, defined on page 8.

Table 1–2

Healthy People 2020, Selected Nutrition and Body Weight Objectives
Many other Objectives for the Nation are available at www.healthypeople.gov.
1. Chronic Diseases
▪▪ Reduce the proportion of adults with osteoporosis.
▪▪ Reduce the death rates from cancer, diabetes, heart disease, and stroke.
▪▪ Reduce the annual number of new cases of diabetes.

2. Food Safety
▪▪ Reduce outbreaks of certain infections transmitted through food.
▪▪ Reduce severe allergic reactions to food among adults with diagnosed food allergy.

3. Maternal, Infant, and Child Health
▪▪ Reduce the number of low-birthweight infants and preterm births.
▪▪ Increase the proportion of infants who are breastfed.
▪▪ Reduce the occurrence of fetal alcohol syndrome (FAS).
▪▪ Reduce iron deficiency among children, adolescents, women of childbearing age, and pregnant women.
▪▪ Reduce blood lead levels in lead-exposed children.
▪▪ Increase the number of schools offering breakfast.

4. Food and Nutrient Consumption
▪▪ Increase vegetables, fruit, and whole grains in the diets of those aged 2 years and older, and reduce solid fats and added sugars.

5. Eating Disorders
▪▪ Reduce the proportion of adolescents who engage in disordered eating behaviors in an attempt to control their weight.

6. Physical Activity and Weight Control
▪▪ Increase the proportion of children, adolescents, and adults who are at a healthy weight.
▪▪ Reduce the proportions of children, adolescents, and adults who are obese.
▪▪ Reduce the proportion of people who engage in no leisure-time physical activity.
▪▪ Increase the proportion of schools that require daily physical education for all students.

7. Food Security
▪▪ Eliminate very low food security among children in U.S. households.
Source: www.healthypeople.gov.

Table 1–3

Elements in the Six Classes of Nutrients
The nutrients that contain carbon are organic.
Carbon

Oxygen

Hydrogen

Nitrogen

Minerals

Carbohydrate

✓

✓

✓

Fat

✓

✓

✓

Protein

✓

✓

✓

✓

b

Vitamins

✓

✓

✓

✓a

b

Minerals
Water

✓
✓

✓

All of the B vitamins contain nitrogen; amine means nitrogen.

a

Protein and some vitamins contain the mineral sulfur; vitamin B12 contains the mineral cobalt.

b

6

Chapter 1 Food Choices and Human Health

✓

Meet the Nutrients
The human body and foods are made of the same materials, arranged in different ways
(see Figure 1–2). When considering quantities of foods and nutrients, scientists often
measure them in grams or fractions of grams, units of weight.

The Energy-Yielding Nutrients Of the four organic nutrients, three are energyyielding nutrients, meaning that the body can use the energy they contain. These
are carbohydrate, fat, and protein, often referred to as the macronutrients, and they
contribute to the calories you consume. Among them, protein stands out for doing
double duty: it can yield energy, but it also provides materials that form structures and
working parts of body tissues. (Alcohol yields energy, too—see Table 1–4 comments.)
Vitamins and Minerals The fourth and fifth classes of nutrients are the vitamins
and the minerals, sometimes referred to as micronutrients because they are present
in tiny amounts in living tissues. These provide no energy to the body. A few minerals serve as parts of body structures (calcium and phosphorus, for example, are major
constituents of bone), but all vitamins and minerals act as regulators. As regulators,
the vitamins and minerals assist in all body processes: digesting food; moving muscles;
disposing of wastes; growing new tissues; healing wounds; obtaining energy from carbohydrate, fat, and protein; and participating in every other process necessary to maintain life. Later chapters are devoted to these six classes of nutrients.
Water Although last on the list, water is foremost in quantity among the six classes
of nutrients in the body. The body constantly loses water, mainly through sweat, breath,
and urine, and that water must constantly be replaced. Without sufficient water, the
body’s cells cannot function.

The Concept of Essential Nutrients When you eat food, then, you are providing
your body with energy and nutrients. Furthermore, some of the nutrients are essential
nutrients, meaning that if you do not ingest them, you will develop deficiencies; the body
cannot make these nutrients for itself. Essential nutrients are found in all six classes of
nutrients. Water is an essential nutrient; so is a form of carbohydrate; so are some lipids,
some parts of protein, all of the vitamins, and the minerals important in human nutrition.
Figure 1–2

Components of Food and the Human Body
Foods and the human body are made of the same materials.

Table 1–4

Energy-Yielding Nutrients
The energy a person consumes in a day’s meals comes
from these three energyyielding nutrients; alcohol, if
consumed, also contributes
energy at a rate of about
7 calories per gram (see note).
Energy Nutrient

Energy

Carbohydrate

4 cal/g

Fat (lipid)

9 cal/g

Protein

4 cal/g

Note: Alcohol is not classed as a nutrient because it
interferes with growth, maintenance, and repair of
body tissues.

grams (g) metric units of weight. About 28 grams
equal an ounce. A milligram is one-thousandth of
a gram. A microgram is one-millionth of a gram.

energy-yielding nutrients the nutrients the
body can use for energy: carbohydrate, fat (also
called lipids), and protein. These also may supply building blocks for body structures.

Vitamins
Minerals
Fat
Protein
Carbohydrate
Water

macronutrients another name for the energyyielding nutrients: carbohydrate, fat, and protein.
micronutrients nutrients required in very small
amounts: the vitamins and minerals.

essential nutrients the nutrients the body cannot make for itself (or cannot make fast enough)
from other raw materials; nutrients that must be
obtained from food to prevent deficiencies.
The Human Body and Its Food

7

You may wonder why fiber, famous for its beneficial health effects, is not listed
among the essential nutrients. The reason is that most fiber passes through the body
unabsorbed, and omitting it from the diet does not reliably cause a specific deficiency
disease. Even so, in research, health benefits often follow eating a fiber-rich diet (Chapter 4 has details).4

Calorie Values Food scientists measure food energy in kilocalories, units of heat.
This book uses the common word calories to mean the same thing. It behooves the
person who wishes to control food energy intake and body fatness to learn the calorie
values of the energy nutrients, listed in Table 1–4. The most energy-rich of the nutrients
is fat, which contains 9 calories in each gram. Carbohydrate and protein each contain
only 4 calories in a gram. Weight, measure, and other conversion factors needed for the
study of nutrition appear in Appendix C at the back of the book.
Scientists have worked out ways to measure the energy and nutrient contents of
foods. They have also calculated the amounts of energy and nutrients various types of
people need—by gender, age, life stage, and activity. Thus, after studying human nutrient requirements (in Chapter 2), you will be able to state with some accuracy just what
your own body needs—this much water, that much carbohydrate, so much vitamin C,
and so forth. So why not simply take pills or dietary supplements in place of food?
Because, as it turns out, food offers more than just the six basic nutrients.
Key Points
▪▪
▪▪
▪▪
▪▪
▪▪

The energy-yielding nutrients are carbohydrates, fats (lipids), and protein.
The regulator nutrients are vitamins and minerals.
Foremost among the nutrients in food is water.
Essential nutrients in the diet prevent deficiencies.
Food energy is measured in calories; nutrient quantities are often measured in grams.

Can I Live on Just Supplements?

fiber a collective term for various indigestible
plant materials, many of which bear links with
human health. See also Chapter 4.

calories units of energy. In nutrition science,
the unit used to measure the energy in foods is
a kilocalorie (also called kcalorie or Calorie): it
is the amount of heat energy necessary to raise
the temperature of a kilogram (a liter) of water
1 degree Celsius. This book follows the common
practice of using the lowercase term calorie
(abbreviated cal) to mean the same thing.

Nutrition science can state what nutrients human beings need to survive—at least for
a time. Scientists are becoming skilled at making elemental diets—life-saving liquid
diets of precise chemical composition for hospital patients and others who cannot eat
ordinary food. These formulas, administered for days or weeks, support not only continued life but also recovery from nutrient deficiencies, infections, and wounds. Formulas can also stave off weight loss in the elderly or anyone in whom eating is impaired.5
Formula diets are essential to help sick people to survive, but they do not enable people to thrive over long periods. Even in hospitals, elemental diet formulas do not support
optimal growth and health and may even lead to medical complications. Although serious problems are rare and can be detected and corrected, they show that the composition of these diets is not yet perfect for all people in all settings.
Lately, marketers have taken these liquid supplement formulas out of the medical
setting and have advertised them heavily to healthy people of all ages as “meal replacers” or “insurance” against malnutrition. The truth is that real food is superior to such
supplements. Most healthy people who eat a nutritious diet need no dietary supplements at all.

ingredients of known chemical composition;
intended to supply, to the greatest extent
possible, all essential nutrients to people who
cannot eat foods.

Food Is Best Even if a person’s basic nutrient needs are perfectly understood and
met, concoctions of nutrients still lack something that foods provide. Hospitalized clients who are fed nutrient mixtures through a vein often improve dramatically when
they can finally eat food. Something in real food is important to health—but what is it?
What does food offer that cannot be provided through a needle or a tube? Science has
some partial explanations, some physical and some psychological.
In the digestive tract, the stomach and intestine are dynamic, living organs, changing constantly in response to the foods they receive—even to just the sight, aroma, and
taste of food. When a person is fed through a vein, the digestive organs, like unused
muscles, weaken and grow smaller. Medical wisdom now dictates that a person should
be fed through a vein for as short a time as possible and that real food taken by mouth

8

Chapter 1 Food Choices and Human Health

dietary supplements pills, liquids, or powders
that contain purified nutrients or other ingredients (see Controversy 7).
elemental diets diets composed of purified

should be reintroduced as early as possible. The digestive organs also release hormones
in response to food, and these send messages to the brain that bring the eater a feeling
of satisfaction: “There, that was good. Now I’m full.” Eating offers both physical and
emotional comfort.

Brian Chase/Shutterstock.com

Complex Interactions Foods are chemically complex. In addition to their nutrients, foods contain phytochemicals, compounds that confer color, taste, and other
characteristics to foods. Some may be bioactive food components that interact with
metabolic processes in the body and may affect disease risks. Even an ordinary baked
potato contains hundreds of different compounds. Nutrients and other food components
interact with each other in the body and operate best in harmony with one another. In
view of all this, it is not surprising that food gives us more than just nutrients. If it were
otherwise, that would be surprising.
Key Points
▪▪ Nutritious food is superior to supplements for maintaining optimal health.
▪▪ Most healthy people who eat a nutritious diet do not need supplements at all.

The Challenge of Choosing Foods
LO 1.4

Some foods offer phytochemicals in
addition to the six classes of nutrients.

Give examples of the challenges and solutions to choosing a healthpromoting diet.

Well-planned meals convey pleasure and are nutritious, too, fitting your tastes, personality, family and cultural traditions, lifestyle, and budget. Given the astounding numbers and varieties available, consumers can easily lose track of what individual foods
contain and how to put them together into a health-promoting diet. A few definitions
and basic guidelines can help.

The Abundance of Foods to Choose From
A list of the foods available 100 years ago would be relatively short. It would consist
mostly of whole foods—foods that have been around for a long time, such as vegetables, fruit, meats, milk, and grains (Table 1–5 defines food types, p. 10; terms in tables
are in black bold type, margin definitions are in blue). These foods have been called
basic, unprocessed, natural, or farm foods. By any name, these foods form the basis
of a nutritious diet. On a given day, however, well over 80 percent of our population
­consumes too few servings of fruit and vegetables each day.6 And when people do
choose to eat a vegetable, the one they most often choose is potatoes, usually prepared
as French fries. Such choices, repeated over time, make development of chronic diseases
more likely.
The number and types of foods supplied by the food industry today is astounding, as
Figure 1–3 (p. 10) illustrates. Tens of thousands of foods now line the market shelves—
many are processed mixtures of the basic ones, and some are constructed entirely from
highly processed ingredients.7 Ironically, this abundance often makes it more difficult,
rather than easier, to plan a nutritious diet.
The food-related terms defined in Table 1–5 reveal that all types of food—including
fast foods, processed foods, and ultra-processed foods—offer various con­
stituents to the eater, some more health-promoting than others.8 You may also hear
about functional foods, a marketing term coined to identify those foods containing
substances, natural or added, that might lend protection against chronic diseases. The
trouble with trying to single out the most health-promoting foods is that almost every
naturally occurring food—even chocolate—is functional in some way with regard to
human health.9
The extent to which foods support good health depends on the calories, nutrients,
and phytochemicals they contain. In short, to select well among foods, you need to
know more than their names; you need to know the foods’ inner qualities. Even more

The Challenge of Choosing Foods

phytochemicals bioactive compounds in
plant-derived foods (phyto, pronounced FYE-toe,
means “plant”).

bioactive having chemical or physical properties that affect the functions of the body tissues.
See Controversy 2.

9

Table 1–5

Glossary of Food Types
▪▪ enriched foods and fortified foods foods to which nutrients

▪▪

▪▪

▪▪

▪▪

have been added. If the starting material is a whole, basic
food such as milk or whole grain, the result may be highly
nutritious. If the starting material is a concentrated form of
sugar or fat, the result is less nutritious.
fast foods restaurant foods that are available within minutes
after customers order them—traditionally, hamburgers,
French fries, and milkshakes; more recently, salads and
other vegetable dishes as well. These foods may or may not
meet people’s nutrient needs, depending on the selections
provided and on the energy allowances and nutrient needs
of the eaters.
functional foods whole or modified foods that contain bioactive food components believed to provide health benefits,
such as reduced disease risks, beyond the benefits that their
nutrients confer. However, all nutritious foods can support
health in some ways; Controversy 2 provides details.
medical foods foods specially manufactured for use by
people with medical disorders and administered on the
advice of a physician.
natural foods a term that has no legal definition but is often
used to imply wholesomeness.

▪▪ organic foods understood to mean foods grown without syn-

▪▪

▪▪

▪▪

▪▪

thetic pesticides or fertilizers. In chemistry, however, all foods
are made mostly of organic (carbon-containing) compounds.
processed foods foods subjected to any process, such as
milling, alteration of texture, addition of additives, cooking, or
others. Depending on the starting material and the process, a
processed food may or may not be nutritious.
staple foods foods used frequently or daily—for example, rice
(in East and Southeast Asia) or potatoes (in Ireland). Many of
these foods are sufficiently nutritious to provide a foundation
for a healthful diet.
ultra-processed foods a term used to describe highly palatable
food products of manufacturing made with industrial ingredients and additives, such as sugars, refined starches, fats, salt,
and imitation flavors and colors, with little or no whole food
added. Examples: sugary refined breakfast cereals, candies,
cookies, fried chicken nuggets, potato “tots,” ready-to-heat
meals, snack chips and cakes, and soft drinks.
whole foods milk and milk products; meats and similar foods
such as fish and poultry; vegetables, including dried beans and
peas; fruit; and grains. These foods are generally considered to
form the basis of a nutritious diet. Also called basic foods.

important, you need to know how to combine foods into nutritious diets. Foods are
not nutritious by themselves; each is of value only insofar as it contributes to a nutritious diet. A key to wise diet planning is to make sure that the foods you eat daily, your
staple foods, are especially nutritious.
Key Point
▪▪ Foods that form the basis of a nutritious diet are whole foods, such as ordinary
milk and milk products; meats, fish, and poultry; vegetables and dried peas and
beans; fruit; and grains.
Figure 1–3

Grocery Options Then and Now

10

Chapter 1 Food Choices and Human Health

© Polara Studios, Inc.

... but now many foods look like this.

Baloncici/Shutterstock.com

All foods once looked like this ...					

How, Exactly, Can I Recognize a Nutritious Diet?
A nutritious diet is really an eating pattern, a habitual way of choosing foods,
with five characteristics. First is adequacy: the foods provide enough of each
essential nutrient, fiber, and energy. Second is balance: the choices do not
overemphasize one nutrient or food type at the expense of another. Third
is calorie control: the foods provide the amount of energy you need to
maintain appropriate weight—not more, not less. Fourth is moderation:
the foods do not provide excess fat, salt, sugar, or other unwanted constituents. Fifth is variety: the foods chosen differ from one day to the next. In
addition, to maintain a steady supply of nutrients, meals should occur with
regular timing throughout the day. To recap, then, a nutritious diet is an eating pattern
that follows the A, B, C, M, V principles: Adequacy, Balance, Calorie control, Moderation, and Variety.

StockPhotosArt/Shutterstock.com

Adequacy Any nutrient could be used to demonstrate the importance of dietary
adequacy. Iron provides a familiar example. It is an essential nutrient: you lose some
every day, so you have to keep replacing it, and you can get it into your body only by
eating foods that contain it.† If you eat too few iron-containing foods, you can develop
iron-deficiency anemia. With anemia, you may feel weak, tired, cold, sad, and unenthusiastic; you may have frequent headaches; and you can do very little muscular work
without disabling fatigue. Some foods are rich in iron; others are notoriously poor. If
you add iron-rich foods to your diet, you soon feel more energetic. Meat, fish, poultry,
and legumes are rich in iron, and an easy way to obtain the needed iron is to include
these foods in your diet regularly.
Balance To appreciate the importance of dietary balance, consider a second essential nutrient, calcium. A diet lacking calcium causes poor bone development during
the growing years and increases a person’s susceptibility to disabling bone loss in
adult life. Most foods that are rich in iron are poor in calcium. Calcium’s richest food
sources are milk and milk products, which happen to be extraordinarily poor iron
sources. Clearly, to obtain enough of both iron and calcium, people have to balance
their food choices among the types of foods that provide both nutrients. Balancing
the whole diet to provide enough of every one of the 40-odd nutrients the body needs
for health requires considerable juggling, however. As you will see in Chapter 2, food
group plans ease this task by clustering rich sources of nutrients into food groups that
will help you to achieve both dietary adequacy and balance within an eating pattern
that meets your needs.
Calorie Control

Energy intakes should not exceed or fall short of energy needs.
Named calorie control, this characteristic ensures that energy intakes from food
balance energy expenditures required for body functions and physical activity.
Eating such a diet helps control body fat content and weight. The many strategies that
promote this goal appear in Chapter 9.

Moderation Intakes of certain food constituents such as saturated fats, added
sugars, and salt should be limited for health’s sake. Some people take this to mean
that they must never indulge in a delicious beefsteak or hot-fudge sundae, but they
are misinformed: moderation, not total abstinence, is the key.10 A steady diet of steak
and ice cream might be harmful, but once a week as part of an otherwise healthful eating pattern, these foods may have little impact; as once-a-month treats, these
foods would have practically no effect at all. Moderation also means that limits are
necessary, even for desirable food constituents. For example, a certain amount of fiber
in foods contributes to the health of the digestive system, but too much fiber leads to
nutrient losses.
†

A person can also take supplements of iron, but as later discussions demonstrate, eating iron-rich foods is preferable.

The Challenge of Choosing Foods

eating pattern the combination of foods
and beverages that constitute an individual’s
complete dietary intake over time; a person’s
usual diet.

adequacy the dietary characteristic of providing all of the essential nutrients, fiber, and
energy in amounts sufficient to maintain health
and body weight.

balance the dietary characteristic of providing
foods of a number of types in proportion to each
other, such that foods rich in some nutrients
do not crowd out the diet foods that are rich in
other nutrients.

calorie control the dietary characteristic of
controlling energy intake; a feature of a sound
diet plan.
moderation the dietary characteristic of providing constituents within set limits, not to excess.
variety the dietary characteristic of providing a wide selection of foods—the opposite of
monotony.
legumes (leg-GOOMS, LEG-yooms) beans,
peas, and lentils, valued as inexpensive food
sources of protein, vitamins, minerals, and fiber
that contribute little fat to the diet. Also defined
in Chapter 6.

11

Variety As for variety, nutrition scientists agree that people should not eat the same

Figure 1–4

Components of a Nutritious
Diet
All of these factors help to build a
nutritious diet:

Variety
Variety
Moderation
Moderation
Calorie
Calorie control
control
Balance
Balance
Adequacy
Adequacy

foods, even highly nutritious ones, day after day, for a number of reasons. First, a varied
diet is more likely to be adequate in nutrients. Second, some less-well-known nutrients
and phytochemicals could be important to health, and some foods may be better sources
of these than others. Third, a monotonous diet may deliver large amounts of toxins or
contaminants. Such undesirable compounds in one food are diluted by all the other
foods eaten with it and are diluted still further if the food is not eaten again for several
days. Finally, variety adds interest—trying new foods can be a source of pleasure.
Variety applies to nutritious foods consumed within the context of all of the other
dietary principles just discussed. Relying solely on the principle of variety to dictate food
choices could easily result in a low-nutrient, high-calorie eating pattern with a variety
of nutrient-poor snack foods and sweets. If you establish the habit of using all of the principles just described, you will find that choosing a healthful diet becomes as automatic
as brushing your teeth or falling asleep. Establishing the A, B, C, M, V habit (summed up
in Figure 1–4) may take some effort, but the payoff in terms of improved health is overwhelming. Table 1–6 takes an honest look at some common excuses for not eating well.
Key Point
▪▪ A well-planned diet is adequate, balanced, moderate in energy, and moderate in
unwanted constituents and offers a variety of nutritious foods.

Why People Choose Foods
Eating is an intentional act. Each day, people choose from the available foods, prepare
the foods, and decide where to eat, which customs to follow, and with whom to dine.
Many factors influence food-related choices.

Cultural and Social Meanings Attached to Food Like wearing traditional
clothing or speaking a native language, enjoying traditional cuisines and foodways
can be a celebration of your own or a friend’s heritage. Sharing ethnic foods can be
symbolic: people offering foods are expressing a willingness to share cherished values
with others. People accepting those foods are symbolically accepting not only the person doing the offering but also the person’s culture. Developing cultural competence
is particularly important for professionals who help others to achieve a nutritious diet.11
Cultural traditions regarding food are not inflexible; they keep evolving as people
move about, learn about new foods, and teach each other. Today, some people are ceasing to be omnivorous and are becoming vegetarians. Vegetarians often choose
this lifestyle because they honor the lives of animals or because they have discovered the health and other advantages associated with eating patterns rich in beans,

Table 1–6

What’s Today’s Excuse for Not Eating Well?
If you find yourself saying, “I know I should eat well, but I’m too busy” (or too fond of fast food, or have too little money,
or a dozen other excuses), take note:
▪▪ No time to cook. Everyone is busy. Convenience packages of

fresh or frozen vegetables, jars of pasta sauce, and prepared
meats and salads make nutritious meals in little time.
▪▪ Not a high priority. Priorities change drastically and instantly
when illness strikes—better to spend a little effort now
nourishing your body’s defenses than to spend enormous
resources later fighting illnesses.

▪▪ Crave fast food and sweets. Occasional fast-food meals and

sweets in moderation are acceptable in a nutritious diet.
▪▪ Too little money. Eating right may cost a little more than

eating poorly, but the cost of coping with a chronic illness is
unimaginably high.
▪▪ Take vitamins instead. Vitamin pills or even advertised “nutritional
drinks” cannot make up for consistently poor food choices.

Sources: D. P. Reidlinger, T. A. Sanders, and L. M. Goff, How expensive is a cardioprotective diet? Analysis from the CRESSIDA study, Public Health Nutrition (2017),
epub ahead of print, doi: 10.1017/S1368980016003529; M. M. Abdullah, J. P. Jones, and P. J. Jones, Economic benefits of the Mediterranean-style diet consumption in
Canada and the United States, Food and Nutrition Research (2015), epub, doi: 10.3402/fnr.v59.27541; M. Rao and coauthors, Do healthier foods and diet patterns cost
more than less healthy options? A systematic review and meta-analysis, BMJ Open 3 (2013): e004277.

12

Chapter 1 Food Choices and Human Health

Factors that Drive Food Choices Taste prevails as the
number-one factor driving people’s food choices, with price following closely behind.12 Consumers also value convenience so
highly that they are willing to spend almost half of their food
budgets on meals prepared outside the home. Fewer people are
learning the skills needed to prepare nutritious meals at home.13
Instead, they frequently eat out, bring home ready-to-eat meals,
or have food delivered. When they do cook, they want to prepare
meals in 15 to 20 minutes, using only a few ingredients. Such
convenience incurs a cost in terms of nutrition, however: eating
away from home reduces intakes of fruit, vegetables, milk, and
whole grains. It also increases intakes of calories, saturated fat, sodium, and added sugars. Convenience doesn’t have to mean that nutrition flies out the window, however.
This chapter’s Food Feature (p. 20) explores the trade-offs of time, money, and nutrition
that many busy people face today.
Many other factors—psychological, physical, social, and philosophical—also influence people’s food choices. College students, for instance, often choose to eat at restaurants to socialize, to get out, to save time, or to date; they are not always conscious of
their bodies’ needs for nutritious food. A list of other factors follows:

Kzenon/Shutterstock.com

whole grains, fruit, nuts, and vegetables. Controversy 6 explores
the strengths and weaknesses of both vegetarians’ and meat
eaters’ diets.

Sharing traditional food is a way of sharing
culture.

cuisines styles of cooking.
foodways the sum of a culture’s habits, cus-

▪▪

Advertising. The media have persuaded you to consume these foods.

▪▪

Availability. They are present in the environment and accessible to you.

▪▪

Cost. They are within your financial means.14

cultural subgroups within a population.

▪▪

Emotional comfort. They can make you feel better for a while.

▪▪

Habit. They are familiar; you always eat them.

▪▪

Nutrition and health benefits. You think they are good for you.

▪▪

Personal preference and genetic inheritance. You like the way these foods taste.

cultural competence having an awareness
and acceptance of one’s own and others’ cultures and abilities, leading to effective interactions with all kinds of people.

▪▪

Positive or negative associations. Positive: They are eaten by people you admire, or
they indicate status, or they remind you of fun. Negative: They were forced on you,
or you became ill while eating them.

▪▪

Region of the country. They are foods favored in your area.

▪▪

Social norms. Your companions are eating them, or they are offered and you feel
you cannot refuse them.15

▪▪

Values or beliefs. They fit your religious tradition, square with your political views,
or honor the environmental ethic.

▪▪

Weight. You think they will help control body weight.

toms, beliefs, and preferences concerning food.

ethnic foods foods associated with particular

omnivorous people who eat foods of both plant
and animal origin, including animal flesh.
vegetarians people who exclude from their
diets animal flesh and possibly other animal
products such as milk, cheese, and eggs.

One other factor affects food choices:
▪▪

Nutrition and health benefits. You think they are good for you.16

The next section addresses one of the “how” questions posed earlier in this chapter:
How do we know what we know about nutrition?
Key Points
▪▪ Cultural traditions and social values often revolve around foodways.
▪▪ Many factors other than nutrition drive food choices.

The Science of Nutrition
LO 1.5

Describe the science of nutrition.

Understanding nutrition depends upon a firm base of scientific knowledge. This section
describes the nature of such knowledge.
The Science of Nutrition

13

Figure 1–5

The Scientific Method
Research scientists follow the scientific method. Note that most
research projects result in new questions, not final answers. Thus,
research continues in a somewhat cyclical manner.
OBSERVATION & QUESTION
Identify a problem to be solved or ask
a specific question to be answered.

HYPOTHESIS & PREDICTION
Formulate a hypothesis—a tentative
solution to the problem or answer to
the question—and make a prediction
that can be tested.

EXPERIMENT
Design a study and conduct the
research to collect relevant data.

RESULTS & INTERPRETATIONS
Summarize, analyze, and interpret
the data; draw conclusions.

HYPOTHESIS SUPPORTED

THEORY
Develop a theory that integrates
conclusions with those from
numerous other studies.

HYPOTHESIS NOT SUPPORTED

NEW OBSERVATIONS
& QUESTIONS

Unlike sciences such as astronomy and physics,
nutrition is a relatively young science. Most nutrition research has been conducted since 1900. The
first vitamin was identified in 1897, and the first
protein structure was not fully described until the
mid-1940s. Because nutrition science is an active,
changing, growing body of knowledge, new findings often seem to contradict one another or are
subject to conflicting interpretations. Bewildered
consumers complain in frustration, “Those scientists don’t know anything. If they don’t know
what’s true, how am I supposed to know?”
Yet experimenters have confirmed many nutrition facts with great certainty through repeated
testing. To understand why apparent contradictions
exist, we need to look first at what scientists do.

The Scientific Approach
In truth, it is a scientist’s business not to know.
Scientists obtain facts by systematically asking honest, objective questions—that’s their job.
Following the scientific method (outlined in Fig­
ure 1–5), researchers attempt to answer scientific
questions. They design and conduct various experiments to test for possible answers (see Figure 1–6,
and Table 1–7 on p. 16). When they have ruled out
some possibilities and found evidence for others,
they submit their findings not to the news media
but to boards of reviewers composed of other scientists who try to pick apart the findings and often
call for further evidence before approving publication. Finally, the work is published in scientific
journals where still more scientists can read it.
Then the news reporters read it and write about it,
and the public can read about it, too. In time, other
scientists replicate the experiments and report
their own findings, which either support or refute
earlier conclusions.
Key Points
▪▪ Nutrition is a young and fast-growing science.
▪▪ Scientists ask questions and then design
research experiments to test possible answers.
▪▪ Researchers follow the scientific method and
apply it to various research study designs.

Scientific Challenge
An important truth in science is that one experiment does not “prove” or “disprove”
anything. When a finding has stood up to rigorous repeated testing in several kinds
of experiments performed by several different researchers it is finally considered confirmed. Even then, strictly speaking, science consists not of facts that are set in stone but
of theories that can always be challenged and revised. Some findings, though, such as
the theory that the earth revolves about the sun, are so well supported by observations
and experimental findings that they are generally accepted as facts. What we “know”
in nutrition is confirmed in the same way—through years of replicating study findings. This slow path of repeated studies stands in sharp contrast to the media’s desire
for today’s latest news.17

14

Chapter 1 Food Choices and Human Health

Figure 1–6

Examples of Research Design
gumdrops contain dance-enhancing
power.
Studies of whole populations
(epidemiological studies) provide
another sort of information. Such a
study can reveal a correlation. For
example, an epidemiological study
might find no worldwide correlation of
gumdrop eating with fancy footwork

The type of study chosen for research
depends upon what sort of information the researchers require. Studies
of individuals (case studies) yield
observations that may lead to possible
avenues of research. A study of a
man who ate gumdrops and became
a famous dancer might suggest that
an experiment be done to see if

Case Study

Epidemiological Study
North
Atlantic
Ocean

France

Slovenia

Italy

Croatia
Bosnia

Black Sea
Montenegro

Albania

Spain

Turkey

Greece

Lester V. Bergman/Getty Images

Syria

Morocco

Lebanon
Israel
Jordan

Mediterranean Sea

Algeria
Tunisia
Libya

Egypt

“This country’s food supply contains more
nutrient X, and these people suffer less
­illness Y.”

“This person eats too little of
nutrient X and has illness Y.”

Leslie Newman & Andrew Flowers/Science Source

Laboratory Study

bokan/Shutterstock.com

Intervention Study

“Let’s add foods containing
nutrient X to some people’s
food supply and compare
their rates of illness Y with
the rates of others who don’t
receive the nutrient.”

“Now let’s see if a nutrient X deficiency causes illness Y by inducing a
deficiency in these rats.”

but, unexpectedly, might reveal a correlation with tooth decay.
Studies in which researchers
actively intervene to alter people’s
eating habits (intervention studies)
go a step further. In such a study,
one set of subjects (the experimental group) receives a treatment, and
another set (the control group) goes
untreated or receives a placebo or
sham treatment. If the study is a
blind experiment, the subjects do
not know who among the members
receives the treatment and who
receives the sham. If the two groups
experience different effects, then the
treatment’s effect can be pinpointed.
For example, an intervention study
might show that withholding gumdrops, together with other candies
and confections, reduced the incidence of tooth decay in an experimental population compared to that
in a control population.
Laboratory studies can pinpoint
the mechanisms by which nutrition
acts. What is it about gumdrops that
contributes to tooth decay: their
size, shape, temperature, color,
ingredients? Feeding various forms
of gumdrops to rats might yield the
information that sugar, in a gummy
carrier, promotes tooth decay. In the
laboratory, using animals or plants or
cells, scientists can inoculate with
diseases, induce deficiencies, and
experiment with variations on treatments to obtain in-depth knowledge
of the process under study. Intervention studies and laboratory experiments are among the most powerful
tools in nutrition research because
they show the effects of treatments.

To repeat: the only source of valid nutrition information is slow, painstaking,
well-designed, unbiased, repeatable scientific research. We believe a nutrition fact
to be true because it has been supported, time and again, in experiments designed to
rule out all other possibilities.18 For example, we know that eyesight depends partly
on vitamin A because:
▪▪

In case studies, individuals with blindness report having consumed a steady diet
devoid of vitamin A; and

▪▪

In epidemiological studies, populations with diets lacking in vitamin A are
observed to suffer high rates of blindness; and

▪▪

In intervention studies (controlled clinical trials), vitamin A–rich foods provided to groups of people with vitamin A deficiency reduce their blindness rates
dramatically; and
The Science of Nutrition

15

Table 1–7

Research Design Terms
▪▪ blind experiment an experiment in which the subjects do not

▪▪

▪▪

▪▪

▪▪

know whether they are members of the experimental group
or the control group. In a double-blind experiment, neither
the subjects nor the researchers know to which group the
members belong until the end of the experiment.
case study a study of a single individual. When in clinical settings, researchers can observe treatments and their apparent
effects. To prove that a treatment has produced an effect
requires simultaneous observation of an untreated similar
subject (a case control).
control group a group of individuals who are similar in all
possible respects to the group being treated in an experiment
but who receive a sham treatment instead of the real one.
Also called control subjects.
controlled clinical trial an experiment in which one group
of subjects (the experimental group) receives a treatment
and a comparable group (the control group) receives an
imitation treatment and outcomes for the two are compared.
Ideally, neither subjects nor researchers know who receives
the treatment and who gets the placebo (a double-blind
study).
meta-analysis a computer-driven statistical summary of evidence gathered from multiple previous studies.

▪▪ correlation the simultaneous change of two factors, such

▪▪

▪▪

▪▪

▪▪

▪▪

as the increase of weight with increasing height (a direct or
positive correlation) or the decrease of cancer incidence with
increasing fiber intake (an inverse or negative correlation). A
correlation between two factors suggests that one may cause
the other but does not rule out the possibility that both may
be caused by chance or by a third factor.
epidemiological studies studies of populations; often used in
nutrition to search for correlations between dietary habits and
disease incidence; a first step in seeking nutrition-related
causes of diseases.
experimental group the people or animals participating in an
experiment who receive the treatment under investigation.
Also called experimental subjects.
intervention studies studies of populations in which observation is accompanied by experimental manipulation of some
population members—for example, a study in which half of
the subjects (the experimental subjects) follow diet advice to
reduce fat intakes, while the other half (the control subjects)
do not, and both groups’ heart health is monitored.
laboratory studies studies that are performed under tightly
controlled conditions and are designed to pinpoint causes
and effects. Such studies often use animals as subjects.
placebo a sham treatment often used in scientific studies; an
inert, harmless medication. The placebo effect is the healing
effect that the act of treatment, rather than the treatment
itself, often has.

▪▪

In laboratory studies, animals deprived of vitamin A and only that vitamin
begin to go blind; when it is restored soon enough in the diet, their eyesight
returns; and

▪▪

Further laboratory studies elucidate the molecular mechanisms for vitamin A
activity in eye tissues; and

▪▪

Replication of these studies yields the same results.

▪▪

Later, a meta-anlysis of previous studies also detects the effect.

Now we can say with certainty, “Eyesight depends upon sufficient vitamin A.”
Key Points
▪▪ Single studies must be replicated before their findings can be considered valid.
▪▪ A theory is strengthened when results from follow-up studies with a variety of
research designs support it.

Can I Trust the Media for Nutrition Information?
The news media are hungry for new findings, and reporters often latch onto hypotheses from scientific laboratories before they have been fully tested. A