Wardlaw contemporary nutrition a funcional approach 10th smith 1

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WARDLAW’S CONTEMPORARY NUTRITION Updated with 2015–2020 Dietary Guidelines for

Americans, TENTH EDITION

Published by McGraw-Hill Education, 2 Penn Plaza, New York, NY 10121 Copyright © 2016

by McGraw-Hill Education All rights reserved Printed in the United States of America Previous

editions © 2013, 2011, and 2009 No part of this publication may be reproduced or distributed in any

form or by any means, or stored in a database or retrieval system, without the prior written consent

of McGraw-Hill Education, including, but not limited to, in any network or other electronic storage

or transmission, or broadcast for distance learning.

Some ancillaries, including electronic and print components, may not be available to

customers outside the United States.

This book is printed on acid-free paper

1 2 3 4 5 6 7 8 9 DOW/DOW 21 20 19 18 17 16

ISBN 978-1-259-91832-2

MHID 1-259-91832-7

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Compositor: SPi Global

Title: Wardlaw's contemporary nutrition.

Other titles: Contemporary nutrition

Description: Tenth edition, updated with 2015-2020 dietary guidelines for

Americans / Anne M Smith PH.D., R.D., L.D., Department of Human Sciences,

College of Education and Human Ecology, The Ohio State University, Angela

L Collene M.S., R.D., L.D., Department of Biological and Allied Health

Sciences, Getty College of Arts and Sciences, Ohio Northern University |

New York, NY : McGraw-Hill Education, [2016] | Includes index.

Identifiers: LCCN 2016010131 | ISBN 9781259918322 (alk paper)

Subjects: LCSH: Nutrition—Textbooks.

Classification: LCC QP141 W378 2016b | DDC 612.3—dc23 LC record available at

http://lccn.loc.gov/2016010131

The Internet addresses listed in the text were accurate at the time of publication The inclusion

of a website does not indicate an endorsement by the authors or McGraw-Hill Education, and

McGraw-Hill Education does not guarantee the accuracy of the information presented at

these sites.

Part One Nutrition: A Key to Health

1 Nutrition, Food Choices, and Health 3

2 Guidelines for Designing a Healthy Diet 37

3 The Human Body: A Nutrition Perspective 77

4 Carbohydrates 119

5 Lipids 159

6 Proteins 201

7 Energy Balance and Weight Control 233

8 Vitamins 275

9 Water and Minerals 339

10 Nutrition: Fitness and Sports 403

11 Eating Disorders 443

12 Undernutrition Throughout the World 475

13 Safety of Our Food Supply 511

14 Nutrition During Pregnancy and Breastfeeding 549

15 Nutrition from Infancy Through Adolescence 591

16 Nutrition During Adulthood 635

Brief Contents

Dear Students,

Welcome to the fascinating world of nutrition! We are all nutrition experts, in a sense, because we all eat—several times a day At the same time, though, nutrition can seem a bit confusing One reason for all the confusion is that it seems like “good nutrition”

is a moving target: different authorities have different ideas of how we should eat, and nutrition recommendations are subject

to change! Are eggs good for us or not? Should we eat foods that contain gluten or not? Second, there are so many choices Did you know that the average supermarket carries about 40,000 food and beverage products? Food manufacturers and grocery chains have one purpose—to make a profit Typically, the most aggressively marketed items are not the healthiest This has made shopping very complicated

In addition, as a nation, we eat out a lot When we eat foods that someone else has prepared for us, we surrender control over what is in our food, where the food came from, and how much of it goes on our plates There

is a lot yet to learn, and you are undoubtedly interested in what you should be eating and how the food you eat affects you.

Wardlaw’s Contemporary Nutrition Updated with 2015–2020

Dietary Guidelines for Americans is designed to accurately convey

changing and seemingly conflicting messages to all kinds of students

Our students commonly have misconceptions about nutrition, and many have a limited background in biology or chemistry We teach complex scientific concepts at a level that will enable you to apply the material

to your own life.

This marks the tenth edition of Wardlaw’s Contemporary Nutrition

As in previous editions, we have written it to help you make informed choices about the food you eat We will take you through explanations of the nutrients in food and their relationship to health but will also make you aware of the multitude of other factors that drive food choices To guide you, we refer to many reputable research studies, books, policies, and websites throughout the book With this information at your fingertips, you will be well equipped to make your own informed choices about what and how much to eat There is much to learn, so let’s get started!

Anne Smith Angela Collene

Anne M Smith Ph.D., R.D., L.D.

Department of Human Sciences,

College of Education and Human Ecology

The Ohio State University

Angela L Collene M.S., R.D., L.D.

Department of Biological and Allied Health Sciences,

Getty College of Arts and Sciences Ohio Northern University

Updated with 2015–2020 Dietary Guidelines for Americans

ANNE M SMITH, Ph.D., R.D., L.D., is an associate professor at The Ohio State University She was the recipient of the 1995 Outstanding Teacher Award from the College of Human Ecology, the 2008 Outstanding Dietetic Educator Award from the Ohio Dietetic Association, the 2006 Outstanding Faculty Member Award from the Department of Human Nutrition, and the 2011 Distinguished Service Award from the College of Education and Human Ecology for her commitment to under-graduate education in nutrition Dr Smith’s research in the area of vitamin and mineral metabolism has appeared in prominent nutrition journals, and she was awarded the 1996 Research Award from the Ohio Agricultural Research and Devel-opment Center She is a member of the American Society for Nutrition and the Academy of Nutrition and Dietetics.

ANGELA L COLLENE, M.S., R.D., L.D., began her career at her alma mater, The Ohio State University, as a research dietitian for studies related to diabetes and aging Other professional experiences include community nutrition lecturing and counseling, owner of a personal chef business, and many diverse and rewarding science writing and editing projects Her interests include novel approaches to gly-cemic control, weight management, and—quite predictably for the mother of three little girls—maternal and child nutrition Mrs Collene currently teaches nutrition to nursing students at Ohio Northern University in Ada, Ohio, and is a member of the Academy of Nutrition and Dietetics

About the Authors

With the tenth edition of Wardlaw's Contemporary Nutrition, we remember its founding author, Gordon M Wardlaw We

are saddened that he lost his battle with cancer on January 19, 2014 He was a brilliant example of a man who acts

deci-sively, follows his dreams, and creates a legacy

Dr Wardlaw had a passion for the science of nutrition and the research that supports it With his clear teaching style

and no-nonsense nutrition advice, he demonstrated an exceptional ability to translate scientific principles into practical

knowledge both inside and outside the classroom This skill is what made his book truly “contemporary.” He was

tire-less when it came to staying current and relevant Each edition benefited from his genuine interest in responding to

feed-back from students, colleagues, and instructors He retired from teaching and writing in 2005 to pursue another

passion—building his dream home in California There, in a home he built with his own two hands, he spent the last

years of his life with his family and friends

It has been a privilege for both of us to join Dr Wardlaw as co-authors of this textbook For Anne Smith, he was an

extraordinary colleague, mentor, and friend, who patiently taught her every step of the textbook writing process,

begin-ning with the sixth edition Angela Collene was blessed to have been one of his graduate students at The Ohio State

University, and she first began to assist with revisions to the fifth edition Like so many other students, colleagues, and

friends, we remember Dr Wardlaw as a source of vast knowledge, good humor, and inspiration The best way we know

to honor our dear friend is to carry on his legacy of outstanding textbooks in introductory nutrition Wardlaw's

Contem-porary Nutrition will continue to evolve and reflect current trends and breakthroughs in nutrition science, but

Dr Wardlaw's fingerprints will remain on every page

Special Acknowledgments

It takes a cooperative and dedicated team to produce a successful textbook We are privileged to work with many

tal-ented people that have made contributions to the tenth edition of Wardlaw’s Contemporary Nutrition We are indebted to the

energetic staff at McGraw-Hill Education for their commitment to this textbook We are grateful to Amy Reed and Marija

Magner, our Brand Managers, for their leadership and support of the Wardlaw’s Contemporary Nutrition team Our biggest

“thank you” goes to our Product Developers, Angela FitzPatrick and Darlene Schueller Angie and Darlene enthusiastically

coordinated the editorial team and guided us through every phase of this revision of the textbook We are grateful for, their meticulous editing skills and day-to-day encouragement and patience while we wrote the manuscript We are grateful to our Content Project Managers, April Southwood and MaryJane Lampe, for the careful coordination of the numerous pro-duction efforts needed to create the very appealing and accurate tenth edition We appreciate the thorough work and atten-tion to detail of our copy editor, Marilynn Taylor; proofreaders, Debbie Budde-Bandy and Gina Delaney; photo editors, Lori Hancock and Mary Reeg; and content licensing specialist Lorraine Buczek We thank our designer, Matt Backhaus, who not only guided the visual appeal of this edition but also worked to ensure each page was where it needed to be Finally, we thank our colleagues, friends, and families for their continued support, encouragement, and genuine interest in nutrition.Thank you to reviewers

Our goal is to provide students and educators with the most accurate, up-to-date, and useful textbook possible As with

earlier editions, the quality of the tenth edition of Wardlaw’s Contemporary Nutrition is largely dependent on the thorough,

professional assistance of nutrition educators from academic institutions across the nation We are indebted to these leagues who reviewed the ninth edition, evaluated new material for the tenth edition, participated in instructional sympo-sia, and responded to surveys The advice and suggestions from these colleagues have been used in every chapter and have resulted in a textbook that is current and inviting

Pasadena City College

Sue Ellen Warren

El Camino College

Dana Wassmer

Cosumnes River College

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McGraw-Hill Connect ® Nutrition is a digital teaching and

learning environment that saves students and instructors time

while improving performance over a variety of critical

out-comes From in-site tutorials, to tips and best practices, to live

help from colleagues and specialists—you are never left alone

to maximize Connect’s potential.

• Auto-graded assessments and tutorials

You can easily create customized assessments that will be

automatically graded All Connect content is created by the

authors, so it is pedagogical, instructional, and at

the appropriate level Interactive questions using high-

quality art from the textbook and animations and videos

from a variety of sources take you way beyond multiple

choice Assignable features from the book, such as

News-worthy Nutrition, What Would You Choose?, and Rate Your

Plate, increase student engagement and understanding.

• Gather assessment information

All Connect questions are tagged to a learning outcome,

specific section and topic, and Bloom’s level so you can easily

track assessment data!

Easily assign key features from the book to increase engagement

and learning

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▲ Connect Assessment: Classification Interactive

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▲  Connect Assessment: Labeling Interactive

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as a stand-alone online NutritionCalc Plus is the most

extensive, most accurate database available—over 29,000

foods—from ESHA Research, the leading provider of

nutrient data Create and save recipes allowing students to

accurately reflect their personal food preferences Students

can add up to three profiles The flexibility of multiple

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status as well as the unique nutritional needs of others

NutritionCalc Plus includes a MyPlate report.

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Connect Improves Performance xi

McGraw-Hill Create™ is a self-service website that allows you

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a PDF review copy in just minutes!

Understanding Our Audience

We have written Wardlaw’s Contemporary Nutrition assuming

that our students have a limited background in college-level

biology, chemistry, or physiology We have been careful to

in-clude the essential science foundation needed to adequately

comprehend certain topics in nutrition, such as protein

syn-thesis in Chapter 6 The science in this text has been presented

in a simple, straightforward manner so that undergraduate

students can master the material and apply it to their own

lives The Concept Maps that provide a visual depiction of

macronutrient functions and characteristics are an additional

aid to help students grasp nutrition science.

Featuring the Latest Guidelines

and Research

Nutrition is a dynamic field A vast quantity of research

con-stantly reshapes our knowledge of nutritional science The

tenth edition has been carefully updated to reflect current

scientific understanding, as well as the latest health and

nutri-tion guidelines For everyday diet planning, students will learn

about the 2015–2020 Dietary Guidelines for Americans,

MyPlate, and Healthy People 2020 In discussions about

spe-cific nutrition concerns, the most recent data and

recommen-dations from the American Heart Association, American

Diabetes Association, Institute of Medicine, and American

Psychological Association have been included in this edition.

Connecting Students

to Today’s Nutrition

mended amounts of calcium and vitamin D to protect bone health Experts agree that we should strive to meet our calcium and vitamin D needs from foods first and that more research is needed to better comprehend the benefits and risks associ- ated with calcium and vitamin D supplementation Modification of eating habits to include foods that are good sources of calcium is a better plan of action and appears

to be the safest means to prevent osteoporosis without jeopardizing heart health

In addition to this important mineral, foods that contain calcium also supply other vitamins, minerals, phytochemicals, and fats needed to support health Problems associated with excessive consumption of calcium, such as constipation, are not likely when foods are the primary sources of calcium

In an effort to provide guidance for the public, the U.S Preventive Services Task Force recently reviewed current research studies on the use of vitamin D and calcium supplements to prevent fractures and issued recommendations in its

Vitamin D and Calcium Supplementation to Prevent Fractures report in February 2013

The recommendations apply to adult men and women who live at home They do not apply to those living in assisted living or skilled nursing facilities or who have been diagnosed with osteoporosis or vitamin D deficiency The Task Force conclu- sions are listed in the margin and are based on what is known about the potential benefits and harms of using these supplements

(1) There is not enough evidence to mine whether vitamin D and calcium supplements can prevent fractures in men and in women who have not yet gone through menopause

(2) There is not enough evidence to mine whether vitamin D and calcium supplements with greater than 400 IU

deter-of vitamin D and greater than 1000 mg

of calcium can prevent fractures in noninstitutionalized postmenopausal women

(3) There is enough evidence to mend against daily supplementation with 400 IU or less of vitamin D and

recom-1000 milligrams or less of calcium for the primary prevention of fractures in noninstitutionalized postmenopausal women because lower doses of vitamin

D and calcium supplements do not vent fractures in older women and may increase the risk of kidney stones

pre-The full Task Force statement can be

viewed at

http://www.uspreventi- vitamind/vitdfact.pdf

Calcium supplements decrease risk of hip fracture in women

The Women’s Health Initiative (WHI) clinical trial randomly assigned 36,282 postmenopausal women in the United States to a placebo or 1000 milligram supplement of calcium carbonate plus 400 IU of vitamin D daily for 7.0 years The hypothesis of this study was that calcium plus vitamin D supplementation would reduce hip fracture This study also examined the health benefits and risks of calcium and vitamin D supplementation on total fractures, cardiovascular disease, cancer, and total mortality Women in both groups were also allowed to take per- sonal calcium and vitamin D supplements during the study, which was accounted for during the analysis of the data Regarding bone health, the women who took the assigned calcium and vitamin D supplement but took no personal calcium supplements had a 75 percent lower risk of hip fracture than women who got the placebo and took no personal calcium supplements The results also showed that women assigned to take calcium and vitamin D had no higher risk of heart disease, heart attacks, stroke, colorectal cancer, or total mortality The supple- ment group did have a 17 percent increased risk of kidney stones The authors concluded that long-term use of calcium and vitamin D appears to confer a substantial reduction in the risk of hip fracture among postmenopausal women

Because the risk reduction was significant only in women not taking any tional calcium supplements, it is recommended that women strive to consume the RDA for calcium (1200 milligrams per day) and vitamin D (600 IU/per day up

addi-to age 70 and 800 IU per day over 70) from food and supplements combined

Source: RL Prentice, “Health risks and benefits from calcium and vitamin D

supplementation: Women’s Health Initiative clinical trial and cohort study,” Osteoporosis International, 24, 2, 2013, 567 Copyright © 2013 Springer-Verlag London LTD All rights reserved Used with permission

Newsworthy Nutrition

Check out Connect at www.mcgrawhillconnect.com to further

explore calcium and vitamin D supplements

Confirming pages

318 Contemporary Nutrition: A Functional Approach

processed your food, the higher it is in sodium and the lower it is in potassium

Major contributors of potassium to the adult diet include milk, potatoes, beef, fee, tomatoes, and orange juice (Fig. 9-16).

cof-Diets are more likely to be lower in potassium than sodium because we add salt

to our food, not potassium In fact, North Americans typically consume only 2000

to 3000 milligrams of potassium per day, much less than the AI (see margin) Thus, many of us need to increase potassium intake, preferably by increasing fruit and vegetable intake.

A continually deficient food intake, as may be the case

in alcoholism, can result in a potassium deficiency and low blood potassium levels called hypokalemia People with cer- tain eating disorders whose diets are poor and whose bodies can be depleted of nutrients because of vomiting and diar- rhea are also at risk for potassium deficiency (see Chapter 15)

Other populations especially at risk for potassium deficiency include people on very low-calorie diets and athletes who exercise for prolonged periods These people should com- pensate for potentially low body potassium by consuming potassium-rich foods.

GETTING TOO MUCH POTASSIUM

If the kidneys function normally, typical food intakes will not lead to potassium toxicity Thus, no Upper Level for potassium has been set When the kidneys function poorly, potassium builds in the blood, inhibiting heart function and leading to a slowed heartbeat If left untreated, the heart

Some people take diuretics to lower their blood pressure

Diuretics cause the kidneys to excrete more urine but at the same time may increase urinary excretion of minerals

This is nutritionally relevant for regulation of blood levels

of potassium, magnesium (see Chapter 11), and zinc (see Chapter 13) People who take potassium-wasting diuretics need to carefully monitor their dietary intake of this mineral Increased intake of fruits and vegetables or potas- sium chloride supplements are prescribed by physicians

Examples:

Hydrochlorothiazide (Microzide) Furosemide (Lasix)

• Whole-grain products

Grains Vegetables

Newsworthy Nutrition, a feature in each chapter, highlights

the use of the scientific method in recently published research studies that relate to the chapter topics In addition, assignable questions in Connect take learning a step farther by asking students to read primary literature and apply what they have learned.

In the new margin feature, Medicine Cabinet, we present

information on common medications used to treat diseases that have a nutrition connection These features highlight the ways medications can affect nutritional status, as well as ways food and nutrients can affect how medications work.

Throughout the tenth edition, we reinforce the fact that each

person responds differently to nutrients To further

convey the importance of applying nutrition to their personal

lives, we include many examples of people and situations that

resonate with college students We also stress the importance

of learning to intelligently sort through the seemingly endless

range of nutrition messages to recognize reliable

informa-tion and to sensibly apply it to their own lives Our goal is to

provide students the tools they need to eat healthy and make

informed nutrition decisions after they leave this course

Many of these features can be assigned and graded through

Connect Nutrition to help students learn and apply the

infor-mation and engage with the text.

Confirming pages

395

Rate Your Plate

Working for Denser Bones

Osteoporosis and related low bone mass affect many adults in North America, especially older women One-third of all women experience fractures because of this disease, amounting to about 2 million bone fractures per year

Osteoporosis is a disease you can do something about Some risk factors cannot be changed, but others, such as poor calcium intake, can Is this true for you? To find out, complete this tool for estimating your current calcium intake For all the following foods, write the number of servings you eat in a day Total the number of servings in each category amount for each category to estimate your calcium intake for that day

Does your intake meet your RDA set for calcium?

Food Serving Size Number of Servings Calcium (mg) Total Calcium (mg)

Plain low-fat yogurt Fat-free dry milk powder

1 cup ½ cup Total servings _

5 mg Canned sardines (with bones)

Fruit-flavored yogurt Milk: fat-free, reduced-fat, whole, chocolate, buttermilk Calcium-fortified soy rice, or almond milk (e.g., Silk) Parmesan cheese (grated) Swiss cheese

3 ounces

1 cup

1 cup ¼ cup

1 ounce Total servings

5 mg Cheese (all other hard cheese)

Pancakes

1 ounce

3 Total servings _

5 mg Canned pink salmon

Total servings _

5 mg Collards or turnip greens, cooked

Ice cream or ice milk Almonds

½ cup

1 ounce Total servings _

5 mg Chard, cooked

Cottage cheese Corn tortilla Orange

½ cup

1 medium Total servings

_

_

5 mg Kidney, lima, or navy beans, cooked

Broccoli Carrot, raw Dates or raisins Egg Whole-wheat bread Peanut butter

½ cup

1 medium ¼ cup

1 large

1 slice

2 tablespoons Total servings

5 mg Calcium-fortified orange juice

Calcium-fortified snack bars Calcium-fortified breakfast bars

6 ounces

1 each ½ bar Total servings _

5 mg Calcium-fortified chocolate candies

Calcium supplements *

1 each Total servings _

_

X 500 Total calcium intake

5 mg

Other calcium sources to consider include many breakfast cereals (100–250 mg per cup) and some vitamin/mineral supplements (200–500 mg or more per tablet)

*Amount varies, so check the label for the amount in a specific product and then adjust the calculation as needed

Adapted from Topics in Clinical Nutrition, “Putting Calcium into Perspective for Your Clients,” G Wardlaw and N Weese, 11:1, © 1995 Aspen Publishers, Inc

war21391_ch11_358-395.indd 395 23/10/13 10:01 AM

Challenging Students

to Think Critically

The pages of Wardlaw’s Contemporary Nutrition contain numerous

opportunities for students to learn

more about themselves and their

diet and to use their new knowledge

of nutrition to improve their health

These pedagogical elements include

Critical Thinking, Case Studies,

Nutri-tion and Your Health, What Would

You Choose?, and Newsworthy

Nutri-tion Many of the thought-provoking

topics highlighted in these features

are expanded upon in the online

re-sources found in Connect Nutrition.

Confirming pages

288 Contemporary Nutrition: A Functional Approach

8.3 The Functional Roles of Micronutrients

The next five chapters will explore the vitamins and minerals from a functional various roles in the body Keep in mind that each vitamin and mineral has mul- tiple roles in metabolism For example, calcium, best known for its role in bone formation, is also crucial for the transmission of nerve impulses through the body and plays a role in blood clotting Vitamin C contributes to cellular anti- oxidant function, bone health, and metabolism of proteins At all levels—cellular, interrelated roles in maintaining healthy body functions

ENZYMES, COENZYMES, AND COFACTORS

Before moving ahead in your study of the functional roles of vitamins and

miner-als, it is important to understand how enzymes work Enzymes are catalysts for

the rate of a reaction but is not altered by the reaction Most of the chemical tions in the body would not occur (or would occur only at very slow rates) in the absence of catalysts As you will learn in Chapter 10, enzymes are crucial players

reac-in antioxidant reactions, which neutralize free radicals reac-in the body In Chapter 12, you will see that enzymes allow for the breakdown of carbohydrates, lipids, and assembly of triglycerides for storage in adipose tissue These are the roles of just identified and studied

Typically, enzymes are made of proteins, but many such proteins require the aid

of another compound—a cofactor —for biological activity ( Fig. 8-5 ) Frequently, the

assisting compounds are one or more vitamins or minerals A cofactor is a general

enzyme A compound that speeds the

rate of a chemical reaction but is not

altered by the reaction Almost all

enzymes are proteins (some are made

of genetic material)

cofactor A substance (e.g., mineral)

that binds to a specific region on a

protein, such as an enzyme, and is

nec-essary for the protein’s function

In the dietary supplements aisle of the grocery store, the choices are endless—and

expensive Julie, a college sophomore, just read the Academy of Nutrition and

Dietetics’ position paper on nutrient supplementation for her class She learned that

dietary supplements, such as a balanced multivitamin and mineral supplement, can

be a good back-up plan to ensure adequate nutrition, but the jury is still out when

it comes to demonstrating a benefit of dietary supplements for long-term health

About one-third of Americans regularly take nutrient supplements, but it is usually

the people who already consume a healthy diet who take them Getting more than

the recommended amount of a nutrient does not confer additional health benefits

In fact, too much of some vitamins and minerals can lead to toxicity

Julie decides she would rather focus on getting her nutrients from foods How can she get the most vitamins and minerals out of the foods she eats? Answer the

following questions and check your responses at the end of the chapter

1 What factors can damage or reduce vitamins in food?

2 To maximize vitamin content, what should Julie keep in mind as she selects

fresh produce for purchase?

3 How does food processing affect vitamin and mineral content? Does it make a

difference if Julie chooses products with whole grains or refined grains?

4 When storing fruits and vegetables in her apartment, what steps can Julie take

to minimize nutrient losses?

5 Which cooking methods are best for preserving vitamin content?

Getting the Most Nutrition from Your Food

heart muscle can be damaged A heart attack, or myocardial

heart to beat irregularly or to stop About 25% of people do not survive their first heart attack If blood flow to parts of the brain is interrupted long enough, part of the brain dies, caus-

ing a cerebrovascular accident, or stroke.

A heart attack can strike with the sudden force of a hammer, with pain radiating up the neck or down the arm

sledge-slight pain or pressure in the chest Crushing chest pain is a Many times, the symptoms are so subtle in women that death occurs before she or the health professional realizes that a heart attack is taking place If there is any suspicion at all that

Nutrition and Your Health

Lipids and Cardiovascular Disease

Cardiovascular disease is the major killer of North Americans

the term coronary heart disease (CHD) or coronary artery ease (CAD) is used Each year, about 600,000 people die of

dis-people in the United States have a heart attack each year

Women generally lag about 10 years behind men in oping the disease Still, it eventually kills more women than any other disease The cost of coronary heart disease alone is

devel-$108.9 billion each year, which includes the costs of health care services, medications, and lost productivity.

Development of Cardiovascular Disease

The symptoms of cardiovascular disease develop over many

▲ Cardiovascular disease kills more women than any other disease.

plaque A cholesterol-rich substance deposited in the blood sels; it contains various white blood cells, smooth muscle cells,

ves-Confirming pages

Chapter 8

Vitamins

A lthough the vitamins are essential nutrients, the amount

of vitamins we need to prevent deficiency is small Some people believe that consuming vitamins far in excess of their needs provides them with extra energy, protection from disease, and prolonged youth They seem to think that if a little is good, then more must be better More than half of the U.S adult population have taken vitamin and/or mineral supplements on a regular basis, some at unsafe levels

Vitamins are found in plants and animals Plants size all the vitamins they need and are a healthy source of vitamins for animals Animals vary in their ability to synthesize vitamins For example, guinea pigs and humans are two of the few organisms unable to make their own supply of vitamin C Every major public health authority recommends that

synthe-we increase a our intake of fruits and vegetables Which vitamins are especially found in fruits and vegetables? What are some other health-related attributes of fruits and vegetables in general? Which chronic diseases are associ- ated with a poor intake of fruits and vegetables? Should

we take a daily vitamin supplement if we do not include fruits and vegetables in our diet? This chapter provides some answers

8.13 Understand the process of vitamin B-12 absorption and its role in folate metabolism, identify the dietary requirements

for vitamin B-12 needed to avoid deficiency, and identify its food sources

8.14 Describe the functions of vitamin C as well as its dietary requirements, sources, and deficiency and toxicity signs and

symptoms

8.15 Understand the functions and sources of choline and other vitamin-like substances

8.16 Evaluate the use of dietary supplements with respect to their potential benefits and hazards to the body 8.17 Describe how calorie and fat intakes contribute to cancer risk, and understand the role other food constituents play

in inhibiting cancer

8.8 Describe the functions of riboflavin in energy metabolism, and understand the dietary requirements and sources of

riboflavin that will prevent deficiency symptoms

8.9 Describe the functions of niacin in energy metabolism, and list its sources, dietary requirements, and deficiency and

toxicity symptoms

8.10 Describe the functions of vitamin B-6 in amino acid metabo-lism, and understand how to get enough vitamin B-6 in the

diet to avoid a deficiency and prevent toxicity from dietary supplements

8.11 Describe the functions of pantothenic acid and biotin in energy metabolism, understand their dietary requirements,

and list their food sources and deficiency signs and symptoms

8.12 Summarize the functions of folate in cell metabolism, understand the dietary requirements needed to prevent

megaloblastic anemia, and identify its food sources

Think about your choice as you read Chapter 8, then see What the Dietitian Chose at the end of the chapter To learn more about nutrients and energy metabolism, check out the Connect site: www.mcgrawhillconnect.com

What Would You Choose?

Since being accepted into the business program, your courses are getting tougher and you are staying up late doing homework You also need work experience, so you are putting in 20 hours a week at the bookstore

Between classes, homework, work, and hanging out with friends, you are only getting about 4 to 5 hours of sleep a night and barely have time to eat You are feeling exhausted and looking for a good, quick energy source

Which of the following would you choose to get gized? (Supplement Facts for these products are shown

ener-at the end of the chapter.)

a 2-ounce 5-Hour Energy ® shot

b Nature Made ® B-Complex with Vitamin C Dietary Supplement

c Centrum ® Adults Multivitamin and Mineral Supplement

d Several small meals throughout the day and 7 to

9 hours of sleep each night

Untitled-2 275 9/29/14 7:44 PM

The final result is a striking visual program that holds ers’ attention and supports the goals of clarity, ease of com- prehension, and critical thinking The attractive layout and design of this edition are clean, bright, and inviting This creative presentation of the material is geared toward en- gaging today’s visually oriented students.

read-Attractive, Accurate Artwork

Illustrations, photographs, and tables in the text were

created to help students more easily master complex scientific

concepts.

•

Many illustrations were updated or replaced to inspire stu-dent inquiry and comprehension and to promote interest and

retention of information Many were also redesigned to use

brighter colors and a more attractive, contemporary style

• In many figures, color-coding and directional arrows make

it easier to follow events and reinforce interrelationships

Process descriptions appear in the body of the figures This

pairing of the action and an explanation walks students

step-by-step through the process and increases teaching

1

All-trans retinal

separates from opsin.

Opsin triggers a cascade

of changes that send a signal to the brain.

4

All-trans retinal

is enzymatically converted back

Kidneys sense decreased blood flow.

Kidneys activate an enzyme cascade involving angiotensin and aldosterone.

These hormones increase reabsorption

of Na 1 and Cl 2 by the kidneys, which results in increased water retention by the kidneys

Osmoreceptors in the hypothalamus

sense that blood is becoming more

concentrated The hypothalamus

signals the pituitary gland.

The posterior pituitary gland releases

antidiuretic hormone (ADH).

ADH signals the kidneys to retain

more water.

Body fluids are depleted.

Fluid balance is restored.

Kidneys sense decreased blood flow

Body fluid s are depleted.

Kid Kidney neys a s activate a e an e n enzyme cascadee

inv ingy an an tensinan any ldosterone.

Th These hhormones iincrease reabbsorptiion g gof

of Na Na 1 and and Cl Cl 2 by by the the ki kidneys, which ppres ult s in increas ed yywater retentiony by the ki ki dneys ys ys

Osmoreceptors in the hypothalamus

sense that blood is becoming more pp yp

con trated ted T T he hypothal halamugamu s s

i

sig l nal t s thhe it pit it uitary l gl dypand.

Thepo po ste r pititu rry ry gland nd releases

antidiuretic hormone (ADH).pp p y g

ADH

ADH i si gna l lls th the h ki k ki d ddne ys tto t ret i ain

mor

more w e w ate aterr.

Fluid bal anc e i s restore d.

Low body temperature

Low bone mass Muscle tears/stress fractures

Loss of menstrual periods

Blood potassium imbalance

Iron-deficiency anemia

Dental decay

Swollen salivary glands Irritation of the esophagus Stomach ulcers Constipation

Loss of heart tissue

Anorexia Nervosa Bulimia Nervosa

Irregular heart rate

Sleep disturbances Immune dysfunction Infertility

Hypertension High cholesterol Osteoarthritis Fatty liver disease

Atherosclerosis Type 2 diabetes Some types of cancer Sleep apnea

Binge-Eating Disorder

have very little background in human anatomy and ogy, and we know that developing a keen understanding of digestion and absorption early in the semester will help stu- dents understand nutrition in future chapters Therefore, we have gone to great lengths to help students visualize the body systems, especially the digestive system, and the processes that enable the body to use the nutrients in food For example, Figure 3-2 now illustrates the organ systems as we highlight the links between nutrition and each body system Figure 3-5 now more clearly illustrates the exchange of nutrients and wastes between the body’s internal and external environ- ments Figure captions, such as Figure 3-8, now more clearly explain the structures and step-by-step processes of digestion, absorption, and metabolism.

physiol- • Several new terms have been introduced into Chapter 3 to broaden students’ understanding of the relationship between nutrition and human physiology.

• The presentation of body systems has been reorganized slightly to allow for greatest emphasis on the digestive system

in Section 3.9

• We know that students look for quick summaries of important information, so we have made special efforts to make tables more informative and readable For example, Table 3-2 has been expanded to clarify the roles of secretions of the GI tract.

• Discoveries in the field of nutritional genomics highlight the important relationship between nutrition and genetics Section 3.11 has been expanded to show students the importance of tailoring nutrition recommendations to each individual.

• In the Nutrition and Your Health section, we have included many updates to help students sort fact from fiction when it comes to dietary strategies to prevent or treat common ail- ments of the digestive system The section on irritable bowel syndrome has been revised and expanded In addition, we have added information to answer many of students’ ques- tions about celiac disease and nonceliac gluten sensitivity.

• A new Medicine Cabinet feature highlights the nutrition

impli-cations of proton pump inhibitors and H2 blockers.

Chapter 4: Carbohydrates

• A new What Would You Choose?feature focuses on using the

MyPlate food guide to select a meal that provides several sources of carbohydrates.

• The Carbohydrate Concept Map has been enhanced to include definitions of each carbohydrate category.

• The Carbohydrates in Foods section has been rewritten to include subsections (from MyPlate) on whole grains, vegeta- bles, fruits, and dairy.

• Information on alternative sweeteners has been updated and now includes luo han guo, the extract of the monk fruit.

Figure 1-2 is a new illustration depicting the marketing expendi-tures used to promote food and beverages to children and teens

in the United States The pledge to limit food advertising to

chil-dren as part of the Chilchil-dren’s Food and Beverage Advertising

Initiative (CFBAI) is also discussed.

• An update on restaurant menu label regulations is included.

• A grilled chicken sandwich is now used as the example food

for calculating calories.

•

A review of the scientific method behind nutrition recommen-dations has been moved to Chapter 1 (Section 1.5:

How do we know what we know about nutrition?), along with

an introduction to our Newsworthy Nutrition feature that is

used throughout the book The new Figure 1-5 illustrates the

steps used for testing all types of hypotheses.

• Figure 1-7 showing the percentage of adults who were obese

in 2011, as well as other obesity statistics, has been updated.

• A new Newsworthy Nutrition feature,” Health Status of Baby

Boomers Appears Lower Than Previous Generation,” has

been included.

• New evidence that most college students do not gain the

“freshmen fifteen” is included in the Nutrition and Your

Health on Eating Well in College.

• Further Readings have been updated with six new articles.

Chapter 2: Guidelines for Designing a

Healthy Diet

• Chapter 2 has been reorganized to begin with discussion of

the 2015–2020 Dietary Guidelines and 2008 Physical Activity

Guidelines for Americans and end with a description of the

Dietary Reference Intakes.

• “Food Labels and Diet Planning” has been moved to be the

new Nutrition and Your Health followed by a new Case Study,

“Using the Nutrition Facts Label to Make Food Choices.”

• A new What Would You Choose? feature illustrates nutrient

density and energy density of various beverage choices.

• The term proportionality has been introduced in Chapter 2 to

describe the concept of eating more nutrient-dense foods.

• The section on blood glucose response to food has been

updated to emphasize the concept of glycemic index rather

than glycemic load of foods.

• Information on sugar intake has been rewritten to highlight

the impact of excessive sugar intake on diet quality.

• A new Newsworthy Nutrition feature on the decreased

consumption of added sugars in the United States is

included.

• The Nutrition and Your Health on diabetes has been updated

to include new recommendations for diagnosis from the

American Diabetes Association.

• The Medicine Cabinet margin feature includes information

about drugs used to manage diabetes.

• The discussion of trans fats in foods has been updated and

includes information on proposed legislation for foodservice

• The Newsworthy Nutrition feature focuses on new research on

the primary prevention of cardiovascular disease with a

Medi-terranean diet.

• The Nutrition and Your Health section on the development

of cardiovascular disease now includes a description of the

action of macrophages and foam cells in the production of

plaque in the arterial walls.

•

The beneficial effects of dark chocolate on LDL and HDL cho-lesterol levels are highlighted.

• The Medicine Cabinet feature summarizes medications

com-monly used to treat and prevent atherosclerosis.

• The Further Readings include six new references.

Chapter 6: Proteins

• The synthesis of a peptide bond is illustrated in Figure 6-2.

• ogy to describe protein synthesis.

A cookbook, with recipes and ingredients, is used as an anal- • New trends in meat and poultry consumption in the United States are compared to those around the world.

• The section on soy and nut allergy has been updated and includes a new illustration (Figure 6-10).

• Gluten sensitivity is highlighted in a margin note.

• A Newsworthy Nutrition feature summarizes new research on

the link between red meat consumption and increased ture mortality.

prema- • Recent trends in vegetarianism are discussed, including the Meatless Monday initiative.

• The Further Readings include nine new references.

Chapter 7: Energy Balance and Weight Control

• The prevalence and recent trends in obesity are discussed and illustrated in the updated Figure 7-1.

• olism has been expanded and illustrated in the new Figure 7-5.

The discussion of the effect of lean body mass on basal metab- • Information on expected weight loss from energy restriction has been revised to reflect the latest evidence.

• Body Mass Index categories are listed in Table 7-1.

• The metabolic effects of abdominal obesity are discussed, as well as the effect of excess body fat on the appetite regulating hormone, leptin.

• An expanded discussion of portion control and the basics of the Volumetrics Diet are included.

• A new section, Controlling Hunger, including Conquering the Weight-Loss Plateau, has been added.

• tured in a margin box.

Information on calorie estimations on exercise machines is fea- • Mindful eating is included in the Behavior Modification section.

• phone applications is included.

• The What Would You Choose? feature explores the use of dietary

supplements as a source of energy.

• Newly redesigned figures throughout the chapter illustrate food sources of the vitamins with reference to the food groups pictured on MyPlate.

Connecting with the Latest Updates xvii

• A new Figure 8-1 summarizes the functional roles of the

vitamins.

• The discussions of each micronutrient have been reorganized

and expanded to touch upon functions, deficiency diseases,

food sources, daily requirements, and toxicity in a consistent,

• A new Newsworthy Nutrition feature explores the relationship

between B vitamins and cognitive function.

• A new Figure 8-29 illustrates the steps involved in digestion

and absorption of vitamin B-12.

• Several new Medicine Cabinet features discuss the nutritional

implications of anticoagulant medications, methotrexate,

vari-ous medications that affect vitamin B-12 absorption, and use

of vitamin A derivatives for acne treatment.

• Tables 8-4 and 8-5 have been updated to enhance readability

and quickly summarize pertinent information on the

func-tions, requirements, food sources, deficiency, and toxicity of

the vitamins.

• The discussion of choline has been revised and expanded to

reflect the latest research.

• The new Nutrition and Your Health section on Nutrition and

Cancer reflects the latest recommendations from the American

Cancer Society and American Institute for Cancer Research.

Chapter 9: Water and Minerals

are discussed, including the Newsworthy Nutrition feature on

the ability of calcium supplements to decrease the risk of hip

fractures in women.

•

The T-score scale used for diagnosing osteoporosis is illus-trated in Figure 9-21.

• per metabolism, Wilson’s disease and Menkes disease, are introduced.

Within the section on copper, two genetic defects of cop- • A Newsworthy Nutrition feature presents the results of the

SELECT trial on use of antioxidant supplements to prevent cancer.

• A description of controversy surrounding fluoridation of the water supply is now included in the section on fluoride.

• Two new Medicine Cabinet features explain the nutritional

relevance of medications used to control blood pressure and bone loss.

Chapter 10: Nutrition: Fitness and Sports

• A new section on achieving and maintaining fitness shows how to use the FITT principle to design an effective fitness program at any level.

• A discussion of fat adaptation is now included in the section

on energy sources for exercising muscles.

• The dangers of cutting weight and the female athlete triad are explored, pointing students to information on eating disorders presented in Chapter 11.

• The discussion of the controversial topic of protein needs of athletes has been updated with the latest research.

• New content on the relevance of B vitamins and antioxidants for athletic performance has been included.

• Tables 10-6 and 10-10 have been updated to reflect new sports nutrition products on the market.

• We realized that much of our discussion of sports nutrition in previous editions was strictly applicable to endurance activi- ties, such as long-distance running and cycling Advances in sports nutrition research allow for the application of dietary strategies for a wider variety of sports Therefore, we have revised and reorganized the chapter to present dietary strate- gies to enhance physical performance in muscular strength and power sports in addition to aerobic, endurance activities.

Chapter 11: Eating Disorders

• tion to environmental triggers in the development of eating disorders Discussions of origins of eating disorders through- out the chapter have been updated accordingly.

Research now shows the importance of genetic factors in addi- • With the 2013 release of the Diagnostic and Statistical Manual

classified as a distinct eating disorder Now, a new Section 11.4

is devoted to presenting the most current research on eating disorder Figure 11-1 now illustrates physical effects of binge-eating disorder in addition to those of anorexia nervosa and bulimia nervosa.

binge- • Tables 11-1 and 11-2 have been updated to include DSM-5

revised diagnostic criteria for anorexia nervosa and bulimia

nervosa References to purging have been revised to reflect the preferred term, compensatory behaviors The new

Figure 11-3 presents a striking example of one of the physical effects of self-induced vomiting.

• The concerns of the American Heart Association regarding the GRAS listing for sodium and the concerns of other groups about FDA procedures for regulating and monitoring the safety of food additives are considered.

• Positive health effects of coffee consumption are discussed.

• Table 13-10 lists updated information on what you can do to reduce exposure to pesticides.

• The Dirty Dozen™ and Clean Fifteen lists are now included.

• New sections, Environmental Contaminants in Fish and Sustainable Seafood, have been added.

• The Hazard Analysis Critical Control Point (HACCP) tool

in the battle against foodborne illness is now discussed, as well as food safety tips for what to do when the power goes out.

• The Further Readings include eight new references.

Chapter 14: Nutrition During Pregnancy

and Breastfeeding

• Chapter 14 now opens with a new Section 14.1 on Nutrition and Fertility In this section, we discuss the importance of weight management and other nutritional strategies for both men and women to optimize chances of conception Polycystic ovary syndrome is defined, and management options are discussed.

• Updated information on the fetal origins hypothesis of health and disease has been introduced The concept is first defined in Section 14.1, and current research that relates the fetal origins hypothesis to various aspects of nutritional status is woven throughout the chapter.

• In Section 14.2, the discussion of harmful exposures during pregnancy has been expanded to include more information on the effects of maternal use of both legal and illegal drugs.

• Our discussion of success in pregnancy places special emphasis

on starting pregnancy at a healthy BMI and gaining weight within the recommendations of the Institute of Medicine

To highlight this point, a new Newsworthy Nutrition feature

explains a link between gestational weight gain and future nitive abilities of the offspring.

cog- • In Section 14.4, we now include information on the importance

of adequate vitamin D intake during pregnancy.

• The terminology regarding hypertensive disorders of pregnancy (formerly called pregnancy-induced hypertension) has been

updated to reflect current medical literature.

• Section 14.7, including Table 14-5, has been revised to show even more advantages of breastfeeding for both the mother and the infant.

• A thorough discussion of folate and neural tube defects has been moved from Chapter 8 to the Nutrition and Your Health section of Chapter 14.

• We have updated terminology used to describe

current medical literature In addition, a new Figure 14-11 illustrates an infant with this disorder.

• Although eating disorders are still most prevalent among

young women, additional information is presented on eating

disorders that occur among men and older women.

• References to famous figures who have dealt with eating

disorder have been updated to be more relevant to a younger

generation of students.

• In the discussions of treatment of anorexia nervosa, bulimia

nervosa, and binge-eating disorder, the most up-to-date

infor-mation has been broken down into components of nutrition,

psychological, and pharmacological therapy.

• A new Medicine Cabinet feature discusses the use of

antide-pressant medications for treatment of eating disorders.

• The section on other, lesser-known eating disorders, such as

pica, purging disorder, night eating syndrome, and

subthresh-old eating disorders, has been updated to reflect new

informa-tion in DSM-5 In addiinforma-tion, we have described several emerging

disordered eating patterns, such as diabulimia and orthorexia.

Chapter 12: Undernutrition Throughout

the World

• The concept of nutrition security is introduced in the

discussion of world hunger and food security.

•

Global undernutrition is discussed and illustrated region-by-region in Figure 12-1.

• The United Nations Millennium Development Goals (MDGs)

and targets are presented in Table 12-1 and are used as

bench-marks throughout the chapter.

• A Newsworthy Nutrition feature summarizes research on the

relationship between maternal iodine deficiency and lower

educational outcomes in their offspring.

Connecting with the Latest Updates xix

• ated beverages now appear in Section 15.6 on nutrition for teen- agers In addition, we address the extremely harmful practice of underage alcohol consumption.

Special emphases on reducing intake of fast foods and caffein- • A Newsworthy Nutrition feature on possible links between diet

and acne is found in Section 15.6.

• The Nutrition and Your Health section on food allergies and intolerances has been updated with new statistics and terminol- ogy to reflect current medical literature.

Chapter 16: Nutrition During Adulthood

• A new Figure 16-1 illustrates demographic changes that will impact health care in coming years.

• We present current research on nutrition and longevity that underscores the importance of maintaining a healthy weight, consuming a plant-based diet, and continuing to be physically active.

• ommendations for older adults is presented.

In Section 16.2, the latest research on protein and sodium rec- • Our discussion of physiological factors that affect nutritional status of older adults in Section 16.3 and Table 16-2 has been reorganized and expanded to enhance students’ understanding

of the nutritional needs of the world’s fastest-growing tion group In particular, we have updated our discussions of oral health and physical activity To address the unique con- cerns of older adults, such as sarcopenic obesity and declining bone health, the exercise recommendations for older adults now include endurance, strength-training, flexibility, and bal- ance exercises.

popula- • Table 16-3 now includes a larger variety of complementary and alternative therapies commonly used by older adults.

• tion on nutrition implications of alcohol consumption The term

and alcohol dependence, reflecting the updates of DSM-5 The

diagnostic criteria for alcohol use disorders have been included

in the feature.

Chapter 15: Nutrition from Infancy Through

Adolescence

• In Section 15.1, we have updated Figure 15-1 to illustrate the

application of revised growth charts from WHO and the CDC

The definitions of underweight, healthy weight, overweight, and

reflect current medical literature.

In Sections 15.4 and 15.5, we have reorganized the presenta-tion of strategies to improve nutriIn Sections 15.4 and 15.5, we have reorganized the presenta-tional status of preschool and

school-age children We included a new Table 15-5 to show the

energy needs of young children Throughout these sections,

we have incorporated more hands-on examples of how to

apply scientific recommendations at home Table 15-7 has been

updated to clearly identify foods that are potential choking

haz-ards for young children.

obesity and comorbid conditions within Section 15.4 We point

to specific strategies, such as eating breakfast and avoiding

sugar-sweetened beverages, to prevent or correct this growing

public health problem.

• An updated discussion of nutrition education and the school

breakfast and lunch programs has been added.

Preface iv

Contents

Chapter 1 Nutrition, Food Choices,

and Health 3

1.1 Why Do You Choose the Food You Eat? 4

1.2 How Is Nutrition Connected to Good Health? 8

1.3 What Are the Classes and Sources of Nutrients? 10

1.4 What Math Concepts Will Aid Your Study of Nutrition? 15

1.5 How Do We Know What We Know About Nutrition? 17

1.6 What Is the Current State of the North American Diet

and Health? 20

1.7 What Can You Expect from Good Nutrition and a Healthy

Lifestyle? 25

Nutrition and Your Health: Eating Well in College 28

Case Study: Typical College Student 29

Chapter 2 Guidelines for Designing a Healthy

Diet 37

2.1 A Food Philosophy That Works 38

2.2 Dietary and Physical Activity Guidelines 43

2.3 MyPlate—A Menu-Planning Tool 49

2.4 States of Nutritional Health 56

2.5 Measuring Your Nutritional State 58

2.6 Specific Nutrient Standards and Recommendations 612.7 Evaluating Nutrition Information 64

Nutrition and Your Health: Food Labels and Diet Planning 66 Case Study: Using the Nutrition Facts Label to Make Food Choices 71

Chapter 3 The Human Body: A Nutrition Perspective 77

3.1 Nutrition’s Role in Human Physiology 783.2 The Cell: Structure, Function, and Metabolism 793.3 Body Systems 82

3.4 Cardiovascular System and Lymphatic System 843.5 Urinary System 87

3.6 Nervous System 883.7 Endocrine System 893.8 Immune System 913.9 Digestive System 923.10 Nutrient Storage Capabilities 1013.11 Nutrition and Genetics 102

Nutrition and Your Health: Common Problems with Digestion 107 Case Study: Gastroesophageal Reflux Disease 108

4.4 Making Carbohydrates Available for Body Use 134

Case Study: Problems with Milk Intake 136

4.5 Putting Carbohydrates to Work in the Body 1384.6 Carbohydrate Needs 141

Nutrition and Your Health: Diabetes—When Blood Glucose Regulation Fails 147

Case Study: Worried About Grandma 361

9.7 Phosphorus (P) 3689.8 Magnesium (Mg) 3719.9 Iron (Fe) 374

Chapter 5 Lipids 159

5.1 Lipids: Common Properties 160

5.2 Lipids: Triglycerides, Phospholipids, and Sterols 160

5.3 Fats and Oils in Foods 166

5.4 Making Lipids Available for Body Use 174

5.5 Carrying Lipids in the Bloodstream 176

5.6 Broader Roles for Lipids in the Body 180

5.7 Recommendations for Fat Intake 183

Case Study: Planning a Heart-Healthy Diet 187

Nutrition and Your Health: Lipids and Cardiovascular Disease 189

Chapter 6 Proteins 201

6.1 Amino Acids—Building Blocks of Proteins 202

6.2 Protein Synthesis and Organization 204

6.3 Protein in Foods 206

6.4 Protein Digestion and Absorption 210

6.5 Putting Proteins to Work in the Body 212

7.5 Treatment of Overweight and Obesity 2497.6 Control of Calorie Intake is Essential for Weight Management 2527.7 Regular Physical Activity Promotes Weight Loss and Maintenance

of a Healthy Weight 2547.8 Behavior Modification Strategies for Weight Management 2557.9 Professional Help for Weight Loss 259

8.1 Vitamins: Vital Dietary Components 276

8.2 Vitamin A (Retinoids) and Carotenoids 279

8.3 Vitamin D (Calciferol or Calcitriol) 285

8.13 Vitamin B-12 (Cobalamin or Cyanocobalamin) 312

8.14 Vitamin C (Ascorbic Acid) 315

Nutrition and Your Health: Minerals and Hypertension 391 Case Study: Focus on the Positive 393

Chapter 10 Nutrition: Fitness and Sports 403

10.1 An Introduction to Physical Fitness 404

10.2 Achieving and Maintaining Physical Fitness 405

10.3 Energy Sources for Exercising Muscles 409

10.4 Tailoring Nutrient Recommendations for Athletes 415

10.5 Specialized Advice for Endurance, Strength, and Power Athletes 425

Case Study: Planning a Training Diet 432

Nutrition and Your Health: Ergogenic Aids and Athletic

Performance 433

Chapter 11 Eating Disorders 443

11.1 From Ordered to Disordered Eating Habits 444

11.2 Anorexia Nervosa 447

Case Study: Eating Disorders—Steps to Recovery 452

11.3 Bulimia Nervosa 454

11.4 Binge-Eating Disorder 458

11.5 Other Eating Disorders 462

11.6 Additional Disordered Eating Patterns 464

11.7 Prevention of Eating Disorders 465

Nutrition and Your Health: Eating Disorder Reflections 467

Chapter 12 Undernutrition Throughout the World 475

12.1 World Hunger: A Crisis of Nutrition Security 47612.2 Undernutrition in the United States 48212.3 Undernutrition in the Developing World 48912.4 Reducing Undernutrition in the Developing World 497

Nutrition and Your Health: Undernutrition at Critical Life Stages 503 Case Study: Undernutrition During Childhood 505

Chapter 13 Safety of Our Food Supply 51113.1 Food Safety: Setting the Stage 512

13.2 Food Preservation—Past, Present, and Future 51613.3 Foodborne Illness Caused by Microorganisms 51713.4 Food Additives 522

13.5 Substances That Occur Naturally in Foods and Can Cause Illness 52613.6 Environmental Contaminants in Food 529

13.7 Food Production Choices 534

Nutrition and Your Health: Preventing Foodborne Illness 540 Case Study: Preventing Foodborne Illness at Gatherings 544

Contents xxiii

Chapter 14 Nutrition During Pregnancy

and Breastfeeding 549

14.1 Nutrition and Fertility 550

14.2 Prenatal Growth and Development 553

14.3 Success in Pregnancy 556

14.4 Increased Nutrient Needs to Support Pregnancy 560

Case Study: Preparing for Pregnancy 566

14.5 Food Plan for Pregnant Women 568

14.6 Physiological Changes of Concern During Pregnancy 570

14.7 Breastfeeding 573

Nutrition and Your Health: Preventing Birth Defects 581

Chapter 15 Nutrition from Infancy Through

Adolescence 591

15.1 Assessing Growth 592

15.2 Infant Nutritional Needs 595

15.3 Guidelines for Infant Feeding 600

Case Study: Undernutrition During Infancy 608

15.4 Toddlers and Preschool Children: Nutrition Concerns 608

15.5 School-Age Children: Nutrition Concerns 616

15.6 Teenage Years: Nutrition Concerns 622

Nutrition and Your Health: Food Allergies and Intolerances 626

Chapter 16 Nutrition During Adulthood 63516.1 The Graying of North America 636

16.2 Nutrient Needs During Adulthood 64116.3 Physiological Factors Related to Nutritional Status of Adults 64616.4 Psychosocial Factors Related to Nutritional Status of Adults 65416.5 Ensuring a Healthful Diet for the Adult Years 656

Case Study: Dietary Assistance for an Older Adult 659 Nutrition and Your Health: Nutrition Implications of Alcohol Consumption 660

Appendix A Daily Values Used on Food Labels A-1Appendix B Diabetes Menu-Planning Tools A-2Appendix C Dietary Intake and Energy Expenditure Assessment A-16

Appendix D Chemical Structures Important in Nutrition A-26

Appendix E Sources of Nutrition Information A-31Appendix F English-Metric Conversions and Metric Units A-34

Glossary G-1Photo Credits C-1Index I-1

Dietary Reference Intakes (DRIs)

Student Learning Outcomes 1 2 Identify diet and lifestyle factors that contribute to the 15 leading causes of death in North America.

1 3 Define the terms nutrition, carbohydrate, protein, lipid (fat), alcohol, vitamin, mineral, water, phytochemical, kilocalorie

(kcal), and fiber.

the weight and calorie content of the energy-yielding nutrients, convert English to metric units, and calculate per- centages, such as percent of calories from fat in a diet.

Chapter 1 is designed to allow you to:

1 1 Describe how our food habits are affected by the flavor, texture, and appearance of food; routines and habits;

early experiences and customs; advertising; nutrition

and health concerns; restaurants; social changes;

eco-nomics; and physiological processes affected by meal

size and composition.

Chapter 1

Nutrition, Food Choices,

and Health

prevention, and what to expect from good nutrition and

a healthy lifestyle.

1 8 Identify food and nutrition issues relevant to college students.

hypotheses and theories in the field of nutrition, including

the determination of nutrient needs.

1 6 List the major characteristics of the North American diet, the food habits that often need improvement, and the key

“Nutrition and Weight Status” objectives of the Healthy

People 2020 report.

Think about your choice as you read Chapter 1, then see What the Dietitian Chose at the end of the chapter To learn more about breakfast choices, check

What Would You Choose?

We begin each chapter with this activity to get you

think-ing We ask you to make a choice that is right for you

using the concepts discussed in the chapter At the end of

each chapter, we provide the logic behind what a dietitian

would recommend.

You were awake last night until 2:30 a m finishing a class

project Unfortunately, your Psychology 101 class meets at

9:00 this morning When your alarm goes off at 7:30 a m ,

you decide to sleep those extra 20 minutes it would take

to sit down and enjoy breakfast at the dining hall What’s

your best time-saving breakfast option? What factors may

hold you back from making the correct choice?

a Skip breakfast but plan to consume a few extra

calories at lunch and dinner.

b Eat a low-fat granola bar and iced coffee from the

vending machines in your dorm.

c Fix yourself a quick bowl of Wheaties with a banana

and low-fat milk along with a yogurt, all from your

dorm room “pantry.”

d Pick up a ham, egg, and cheese bagel.

Research has clearly shown that a lifestyle that includes a diet rich in fruits, vegetables, and whole grains, coupled with regular exercise, can enhance our quality of life in the short term and keep us healthy for many years to come Unfortunately, this healthy lifestyle is not always easy to follow When it comes to “nutrition,” it is clear that some of our diets are out of balance with our metab-olism, physiology, and physical activity level

We begin this chapter with some questions What ences your daily food choices? How important are factors such as taste, appearance, convenience, cost, or value? Is nutrition one of the factors you consider? Are your food choices influencing your quality of life and long-term health? By making optimal dietary choices, we can bring the goal of a long, healthy life within reach This is the primary theme of this chapter and throughout this book.The ultimate goal of this book is to help you find the best path to good nutrition The information presented is based on emerging science that is translated into everyday actions that improve health After completion of your nutri-tion course, you should understand the knowledge behind the food choices you make and recommend to others

influ-We call this achievement of making food choices that are right for you “nutrition literacy.”

1.1 Why Do You Choose the Food You Eat?

In your lifetime, you will eat about 70,000 meals and 60 tons of food Many factors—

some internal, some external—influence our food choices This chapter begins with

a discussion of these factors and ends with a conversation specifically about eating well as a college student In between, we examine the powerful effect of dietary habits in determining overall health and take a close look at the general classes of nutrients—as well as the calories—supplied by the food we eat We also discuss the major characteristics of the North American diet, the food habits that often need

improvement, and the key “Nutrition and Weight Status” objectives in the Healthy People 2020 report A review of the scientific process behind nutrition recommenda-

tions is also included, along with an introduction to our “Newsworthy Nutrition”

feature that you will see throughout the book

Understanding what drives us to eat and what affects food choice will help you understand the complexity of factors that influence eating, especially the effects of our routines and food advertising (Fig.  1-1) You can then appreciate why foods may have different meanings to different people and thus why food habits and preferences of others may differ from yours

WHAT INFLUENCES YOUR FOOD CHOICES?

Food means so much more to us than nourishment—it reflects much of what we think about ourselves In the course of our lives, we spend the equivalent of 4 years eating The Bureau of Labor Statistics estimated that in 2011, Americans spent the equivalent of 19 days eating and drinking If we live to be 80 years old, that will add

up to 4.1 years of eating and drinking Overall, our daily food choices stem from

a complicated mix of biological and social influences (see Fig. 1-1) Let’s examine some of the key reasons we choose what we eat

Flavor, texture, and appearance are the most important factors determining our

food choices Creating more flavorful foods that are both healthy and profitable is

a major focus of the food industry These foods are often referred to as “healthy”

choices or “better for you” products The challenge to the food industry is to match the “taste” of the foods we prefer with the nutrition and health characteristics of these products

Early influences that expose us to various people, places, and events have a tinuing impact on our food choices Many ethnic diet patterns begin as we are intro-duced to foods during childhood Parents can lay a strong foundation knowing that early exposure to food choices during infancy, toddler, and preschool years is important in influencing later health behaviors Developing healthy patterns dur-ing childhood will go a long way to ensure healthy preferences and choices when

con-we are teenagers and adults

Chapter 1: Nutrition, Food Choices, and Health 5

Routines and habits are tied to some food choices Food habits, food

availabil-ity, and convenience strongly influence choices Most of us eat from a core group

of foods with about 100 basic items accounting for 75% of our total food intake

Recent surveys indicate that the most commonly purchased foods in America

are milk (about 30 gallons yearly), ready-to-eat cereal, bottled water (about

25 gallons per year), soft drinks (nearly 50 gallons per year), and bread It is no

surprise that milk and cereal are both on the top-five list because many Americans

eat them together as their daily breakfast Bread is also on the list because it is

typically consumed at every meal in America, making it one of the most common

forms of grain eaten Bottled water has become the drink of choice for business

meetings and other large-group gatherings, including outdoor activities Despite

the popularity of water and milk, Americans still drink nearly twice as many

car-bonated soft drinks per year as either water or milk The large amount of sugar

in many soft drinks is of particular concern because studies have found an

asso-ciation between consumption of sugar-sweetened drinks and obesity in children

(see Chapter 15)

Advertising is a major media tool for capturing the food interest of the consumer

Consumers have more food choices than ever and these choices are well

adver-tised in newspapers, magazines, billboards, radio, television, and now the

Inter-net The food industry in the United States spends billions on advertising Some

of this advertising is helpful, as it promotes the importance of food components

such as calcium and fiber in our diets However, the food industry also advertises

highly sweetened cereals, cookies, cakes, and soft drinks because they bring in the

greatest profits Researchers at Yale University found that in 2009, the 20 largest

FIGURE 1-1 ◀ Food choices are affected by many factors Which have the greatest impact on your food choices?

Food flavor, texture,

and appearance

preferences

Psychological needs

Food customs and culture

Social network

of family and friends

Lifestyle

Food cost Food availability

Education, occupation, and income

▲ Cereal and milk are two of the most commonly purchased foods in America largely because they are eaten together for breakfast every day by many.

fast-food restaurant chains spent $3.8 billion on advertising, primarily television ads Food advertising and marketing have been shown to have a definite effect on weight gain in children and adolescents A 2012 Federal Trade Commission (FTC) report found that although food marketing to youth dropped from $2.1 billion in

2006 to $1.79 billion in 2009 (Fig 1-2), much of the decline was the result of less spending on expensive TV advertising and more spending on cheaper online and mobile media (see Further Reading 9) Recent studies in several Western countries indicate that the association between TV advertising of foods and drinks, and child-hood obesity is especially prevalent in the United States (see Further Readings 3 and 10) Concern for the negative effect of advertising and marketing on the diets and health of children has led to several strategies, including the Children’s Food and Beverage Advertising Initiative (CFBAI), a self-regulatory program launched

by the Council of Better Business Bureaus in 2006 CFBAI participants are 16 aged-food companies and quick-serve restaurants that have pledged to limit their advertising to children to foods meeting science-based nutrition criteria or to not engage in child-directed advertising (see Further Reading 13) Research also indi-cates that mass media influences the onset of eating disorders through its depiction

pack-of extremely thin models as stereotypes pack-of attractive bodies The eating disorders that may result from this type of marketing lead to body distortion and dissatisfac-tion Eating disorders will be introduced in the Eating Well in College section at the end of this chapter and discussed at length in Chapter 11

Restaurant dining plays a significant role in our food choices Restaurant food is often calorie-dense, in large portions, and of poorer nutritional qual-ity compared to foods made at home Fast-food and pizza restaurant menus typically emphasize meat, cheese, fried foods, and carbonated beverages In response to recent consumer demands, restaurants have placed healthier items

on their menus and many are listing nutritional content on their menus tory posting of the calorie content of restaurant items will go into effect soon as

Manda-a result of the heManda-alth cManda-are reform bill thManda-at President BManda-arManda-ack ObManda-amManda-a signed into law in March 2010 The law requires chain restaurants with 20 or more locations

to post the calorie content of their offerings on menus or menu boards with other nutritional information available upon request Food and Drug Administration (FDA) released the proposed regulations in November 2012 While many restau-rants have placed calorie information on their menus, most have delayed their calorie disclosures until menu labeling regulations are approved by the FDA

Time and convenience have become significant influences affecting food choices These stem from a lifestyle that limits the amount of time spent in food preparation (see Further Reading 4) In the 2011 Academy of Nutri-tion and Dietetics Trends Survey, 62% of American adults indicated that

it took too much time to keep track of their diet (see Further Reading 2)

Restaurants and supermarkets have responded to our demanding work schedules and long hours away from home by supplying pre-pared meals, microwavable entrees, and various quick-prep frozen products

Economics play a role in our food choices The 2012 Food and Health Survey indicates that after taste, cost is now the number two reason why people choose the food they do

While the average American now spends less on food than in the past, young adults and those with higher incomes spend the most on food As income increases,

so do meals eaten away from home and preferences for foods such as cookies, chocolate, cheese, and meat

Also keep in mind that as calorie intake increases, so does the food bill Tips for eating well on a college stu-dent’s budget are discussed in the Nutrition and Your Health feature at the end of the chapter

FIGURE 1-2 ▲ This chart shows the marketing expenditures used

to promote food and beverages to children and teens in the United

States in 2009 From Further Reading 9.

Source: Reading 9: 9 Federal Trade Commission: A Review of Food Marketing

to Children and Adolescents, Follow-Up Report, December 2012

Can healthy choices be legislated?

Public health authorities would like

to influence health behaviors by

banning or taxing unhealthy foods

or ingredients However,

indus-tries and many concerned citizens

oppose the expanding reach of the

government This struggle gained

national attention in the summer

of 2014 Mounting evidence for

the link between consumption of

sugar-sweetened beverages and

obesity had prompted the proposal

of a ban on the sale of sugary

drinks in containers larger than

16 ounces in some establishments

With the backing of then-Mayor

Michael Bloomberg, this ban was

approved by the New York City

Board of Health and would have

taken effect in 2013 However,

the beverage industry staunchly

opposed the ban and the New York

Supreme Court invalidated the law

In June 2014, the New York Court

of Appeals ruled that this ban

over-reached the health

depart-ment’s regulatory authority Whose

responsibility is it to determine

which foods are good for you?

Chapter 1: Nutrition, Food Choices, and Health 7

Last but not least, nutrition—or what we think of as “healthy foods”—also

directs our food purchases North Americans who tend to make health-related food

choices are often well-educated, middle-class professionals These same people

are generally health-oriented, have active lifestyles, and focus on weight control

The recent National Health Interview Survey showed that 74% of women in the

study habitually or always read the nutrition labels, whereas only 58% of the men

read labels on food products Label reading was associated with a lower body mass

index (BMI, body weight relative to height), especially in women Women who

read labels had a BMI of 1.48 points lower than women who did not read nutrition

labels This translates to a difference of 8.6 pounds for a woman of average height

(see Further Reading 16)

WHY ARE YOU SO HUNGRY?

Two drives, hunger and appetite, influence our desire to eat These drives

dif-fer dramatically Hunger is primarily our physical, biological drive to eat and is

controlled by internal body mechanisms For example, as foods are digested and

absorbed by the stomach and small intestine, these organs send signals to the liver

and brain to reduce further food intake

Appetite, our primarily psychological drive to eat, is affected by many of the

external food choice mechanisms we discussed in the last section, such as

environ-mental and psychological factors and social customs (see Fig. 1-1) Appetite can be

triggered simply by seeing a tempting dessert or smelling popcorn popping at the

movie theater Fulfilling either or both drives by eating sufficient food normally

brings a state of satiety, a feeling of satisfaction that temporarily halts our desire to

continue eating

A region of the brain helps regulate satiety Imagine a tug-of-war in the brain

The feeding center and the satiety center work in opposite ways to promote

ade-quate availability of nutrients at all times When stimulated, cells in the feeding

center signal us to eat As we eat, cells in the satiety center are stimulated and we

stop eating For example, when we haven’t eaten for a while, stimulation of the

feeding center signals us to eat When the nutrient content in the blood rises after

a meal, the satiety center is stimulated, and we no longer have a strong desire to

seek food Admittedly, this concept of a tug-of-war between the feeding and

sati-ety centers is an oversimplification of a complex process The various feeding and

satiety messages from body cells to the brain do not single-handedly determine

what we eat We often eat because food comforts us (see Further Reading 20)

Almost everyone has encountered a mouthwatering dessert and devoured it, even

on a full stomach It smells, tastes, and looks good We might eat because it is the

right time of day, we are celebrating, or we are seeking emotional comfort to

over-come the blues After a meal, memories of pleasant tastes and feelings reinforce

appetite If stress or depression sends you to the refrigerator, you are mostly

seek-ing comfort, not food calories Appetite may not be a physical process, but it does

influence food intake We will discuss more about this mechanism, including the

effect of meal size and composition on satiety, in Chapter 7 on energy balance and

weight control

PUTTING OUR FOOD CHOICES INTO PERSPECTIVE

The next time you pick up a candy bar or reach for a second helping, remember the

internal and external influences on eating behavior You should now understand

that daily food intake is a complicated mix of biological and social influences Body

cells, nutrients in the blood, hormones, brain chemicals, and our social and family

customs all influence food choices When food is abundant, appetite—not hunger—

most likely triggers eating Satiety associated with consuming a meal may reside

primarily in our psychological frame of mind Also, because satiety regulation is

hunger The primarily physiological (internal) drive to find and eat food, mostly regulated by internal cues to eating.

appetite The primarily psychological (external) influences that encourage

us to find and eat food, often in the absence of obvious hunger.

satiety State in which there is no longer a desire to eat; a feeling of satisfaction.

C R I T I C A L T H I N K I N G

Sarah is majoring in nutrition and

is well aware of the importance

of a healthy diet She has recently been analyzing her diet and is confused She notices that she eats

a great deal of high-fat foods, such as peanut butter, cheese, chips, ice cream, and chocolate, and few fruits, vegetables, and whole grains She also has become hooked on her daily cappuccino with lots of whipped cream What three factors may be influencing Sarah’s food choices? What advice would you give her on how to have her diet match her needs?

1.2 How Is Nutrition Connected

to Good Health?

Fortunately, the foods we eat can support good health in many ways depending on their components You just learned, however, that lifestyle habits and other factors may have a bigger impact on our food choices than the food components them-selves Unfortunately, many North Americans suffer from diseases that could have been prevented if they had known more about the foods and, more importantly, had applied this knowledge to plan meals and design their diet We will now look at the effect these choices are having on our health both today and in the future

WHAT IS NUTRITION?

Nutrition is the science that links foods to health and disease It includes the cesses by which the human organism ingests, digests, absorbs, transports, and excretes food substances

pro-NUTRIENTS COME FROM FOODWhat is the difference between food and nutrients? Food provides the energy (in

the form of calories) as well as the materials needed to build and maintain all body cells Nutrients are the substances obtained from food that are vital for growth and maintenance of a healthy body throughout life For a substance to be considered an

essential nutrient, three characteristics are needed:

• First, at least one specific biological function of the nutrient must be identified

in the body

• Second, omission of the nutrient from the diet must lead to a decline in certain biological functions, such as production of blood cells

• Third, replacing the omitted nutrient in the diet before permanent damage occurs will restore those normal biological functions

WHY STUDY NUTRITION?

As we mentioned in the preface, we are all nutrition experts because we all eat several times a day Nutrition knowledge can be confusing, however, and seem like

a moving target Recommendations may seem to differ depending on their source,

nutrients Chemical substances in

food that contribute to health, many

of which are essential parts of a diet

Nutrients nourish us by providing

calo-ries to fulfill energy needs, materials

for building body parts, and factors to

regulate necessary chemical processes

in the body.

essential nutrient In nutritional terms,

a substance that, when left out of a

diet, leads to signs of poor health The

body either cannot produce this

nutri-ent or cannot produce enough of it to

meet its needs If added back to a diet

before permanent damage occurs, the

affected aspects of health are restored.

not perfect, body weight can fluctuate We become accustomed to a certain amount

of food at a meal Providing less than that amount leaves us wanting more One way to use this observation for weight-loss purposes is to train your eye to expect less food by slowly decreasing serving sizes to more appropriate amounts Your appetite then readjusts as you expect less food Keep track of what triggers your eating for a few days Is it primarily hunger or appetite? The Rate Your Plate activ-ity in this chapter also asks you to keep track of what influences your food intake

on a daily basis

1 What are the factors that influence our food choices?

2 How do hunger and appetite differ in the way they influence our desire to eat?

3 What factors influence satiety?

CONCEPT CHECK 1.1

✔

▲ Many foods are rich sources of nutrients.

Chapter 1: Nutrition, Food Choices, and Health 9

and there are so many choices when shopping for food or eating out We just

learned that nutrition is only one of many factors that influence our eating habits

There is a lot to learn, and we know that you are interested in what you should be

eating and how the food you eat affects you Studying nutrition will help you erase

any misconceptions you have about food and nutrition and make informed choices

about the foods you eat and their relationship to health

Nutrition is a lifestyle factor that is a key to developing and maintaining an

optimal state of health for you A poor diet and a sedentary lifestyle are known

to be risk factors for life-threatening chronic diseases such as cardiovascular

Together, these and related disorders account for two-thirds of all deaths in

North America (Fig. 1-3) (see Further Reading 11) Not meeting nutrient needs in

younger years makes us more likely to suffer health consequences, such as bone

fractures from the disease osteoporosis, in later years At the same time,

tak-ing too much of a nutrient—such as a vitamin A supplement—can be harmful

Another dietary problem, drinking too much alcohol, is associated with many

health problems

U.S government scientists have calculated that a poor diet combined with a lack

of sufficient physical activity contributes to hundreds of thousands of fatal cases of

cardiovascular disease, cancer, and diabetes each year among adults in the United

States Thus, the combination of poor diet and too little physical activity may be

the second leading cause of death in the United States In addition, obesity, which

the American Medical Association recently declared as a disease, is considered the

second leading cause of preventable death in North America (smoking is the first)

When they occur together, obesity and smoking cause even more health problems

▲ Major health problems can be avoided

by a healthy diet, moderate calories, and adequate physical activity.

Cardiovascular

(heart) disease A general term that refers to any disease of the heart and circulatory system This disease is generally char-acterized by the deposition of fatty material in the blood vessels (hardening of the arteries), which in turn

can lead to organ damage and death Also termed coronary heart disease (CHD), as the vessels of the heart are the primary sites of the disease.

Cholesterol A waxy lipid found in all body cells; it has a structure containing multiple chemical rings Cholesterol is

found only in foods of animal origin.

Chronic Long-standing, developing over time When referring to disease, this term indicates that the disease process,

once developed, is slow and lasting A good example is cardiovascular disease.

Diabetes A group of diseases characterized by high blood glucose Type 1 diabetes involves insufficient or no release

of the hormone insulin by the pancreas and therefore requires daily insulin therapy Type 2 diabetes results from either insufficient release of insulin or general inability of insulin to act on certain body cells, such as muscle cells Persons with type 2 diabetes may or may not require insulin therapy.

Hypertension A condition in which blood pressure remains persistently elevated Obesity, inactivity, alcohol intake, excess

salt intake, and genetics may each contribute to the problem.

Kilocalorie (kcal) Unit that describes the energy content of food Specifically, a kilocalorie (kcal) is the heat energy needed to

raise the temperature of 1000 grams (1 liter) of water 1 degree Celsius Although kcal refers to a 1000-calorie

unit of measurement, it is commonly referred to as calories Calories is a familiar term for the energy content

of a food, so we will use it in this book.

Osteoporosis Decreased bone mass related to the effects of aging (including estrogen loss during menopause in women),

genetic background, and poor diet.

Risk factor A term used frequently when discussing the factors contributing to the development of a disease A risk

factor is an aspect of our lives, such as heredity, lifestyle choices (e.g., smoking), or nutritional habits.

*Many bold terms are also defined in the page margins within each chapter and in the glossary at the end of this book.

glucose A six-carbon sugar that exists

in a ring form; found as such in blood and in table sugar bound to fructose;

also known as dextrose, it is one of the

simple sugars.

Obesity and chronic diseases are often preventable An important key to good health and more health care savings is to realize that the cost of prevention, usually when we are children and young adults, is a small fraction of the cost of treating these diseases when we are older.

The good news is that the increased interest in health, fitness, and nutrition shown

by Americans has been associated with long-term decreasing trends for heart disease,

cancer, and stroke (the three leading causes of death) that continued in 2011

Mortal-ity from heart disease, the leading cause of death, has been declining steadily since

1980 As you gain understanding about your nutritional habits and increase your knowledge about optimal nutrition, you will have the opportunity to dramatically reduce your risk for many common health problems Recent research has shown that

a healthy diet along with other healthy lifestyle factors can protect women from den cardiac death A healthy diet was defined as one with a high proportion of veg-etables, fruits, nuts, omega-3 fats, and fish (see Further Reading 6) For additional help, the U.S federal government provides two websites that contain links to many sources

sud-of health and nutrition information (www.healthfinder.gov and www.nutrition.gov)

Other useful sites are www.webmd.com and www.eatright.org.

stroke A decrease or loss in blood flow

to the brain that results from a blood

clot or other change in arteries in the

brain This in turn causes the death of

brain tissue Also called a

cerebrovas-cular accident.

FIGURE 1-3 ▶ Fifteen leading causes

of death in the United States

From Centers for Disease Control and

Prevention, National Vital Statistics Report,

Preliminary Data for 2011, October 10, 2012

(see Further Reading 11) Canadian statistics are

Cancer ∗ Chronic lower respiratory disease

Stroke ∗ Accidents Alzheimer’s disease∗Diabetes mellitus∗

Kidney disease∗

Essential hypertension ∗ Parkinson’s disease Pneumonitis due to solids and liquids

Pneumonia/Influenza

Suicide Blood-borne infections (septicemia) Chronic liver disease and cirrhosis

carbohydrate A compound containing

carbon, hydrogen, and oxygen atoms

Sugars, starches, and fibers are forms

of carbohydrates.

lipid A compound containing much

carbon and hydrogen, little oxygen,

and sometimes other atoms Lipids do

not dissolve in water and include fats,

oils, and cholesterol.

protein Food and body compounds

made of amino acids; proteins contain

carbon, hydrogen, oxygen, nitrogen,

and sometimes other atoms, in a

specific configuration.

vitamin Compound needed in very small

amounts in the diet to help regulate and

support chemical reactions in the body.

mineral Element used to promote

chemical reactions and form body

structures.

water The universal solvent; chemi cally,

H2O The body is composed of about

60% water.

kilocalorie (kcal) Heat energy needed

to raise the temperature of 1000 grams

(1 liter) of water 1 degree Celsius; also

written as Calories.

1 How do we define nutrition?

2 What are the three leading causes of death in which diet plays a part?

CONCEPT CHECK 1.2

✔

1.3 What Are the Classes and Sources

of Nutrients?

To begin the study of nutrition, let’s start with an overview of the six classes of

nutrients You are probably already familiar with the terms carbohydrates,

lipids (fats and oils), proteins, vitamins, and minerals These nutrients, plus

water, make up the six classes of nutrients found in food.

Nutrients can then be assigned to three functional categories: (1) those that

primar-ily provide us with calories to meet energy needs (expressed in kilocalories [kcal]);

(2) those important for growth, development, and maintenance; and (3) those that act to keep body functions running smoothly Some function overlap exists among

macronutrient A nutrient needed in gram quantities in a diet.

micronutrient A nutrient needed in milligram or microgram quantities in

a diet.

simple sugar Carbohydrate composed

of only one (monosaccharide) or two (disaccharide) sugar units.

complex carbohydrate Carbohydrate composed of many sugar units (poly- saccharide) Examples include glyco- gen, starch, and fiber.

starch A complex carbohydrate made

of multiple units of glucose attached together in a form the body can

digest.

Chapter 1: Nutrition, Food Choices, and Health 11

these categories (Table 1-2) The energy-yielding nutrients (carbohydrates, lipids, and protein) along with water are needed in relatively large amounts, so they are

called macronutrients Vitamins and minerals are needed in such small amounts in the diet that they are called micronutrients.

CARBOHYDRATES

Chemically, carbohydrates can exist in foods as simple sugars and complex

carbo-hydrates Simple sugars, frequently referred to as sugars, are relatively small

mol-ecules These sugars are found naturally in fruits, vegetables, and dairy products

Table sugar, known as sucrose, is an example of a simple sugar that is added to many foods we eat Glucose, also known as blood sugar or dextrose, is an example of a

simple sugar in your blood Complex carbohydrates are formed when many

sim-ple sugars are joined together For examsim-ple, plants store carbohydrates in the form of

starch, a complex carbohydrate made up of hundreds of glucose units Breads,

cere-als, grains, and starchy vegetables are the main sources of complex carbohydrates

During digestion, complex carbohydrates are broken down into single sugar

mole-cules (such as glucose) and absorbed via cells lining the small intestine into the stream (see Chapter 3 for more on digestion and absorption) However, the bonds between the sugar molecules in certain complex carbohydrates, called fiber, cannot be

blood-broken down by human digestive processes Fiber passes through the small intestine undigested to provide bulk for the stool (feces) formed in the large intestine (colon)

Aside from enjoying their taste, we need sugars and other carbohydrates in our diets primarily to help satisfy the calorie needs of our body cells Carbohy-drates provide a major source of calories for the body, on average 4 kcal per gram

Glucose, a simple sugar that the body can derive from most carbohydrates, is a major source of calories for most cells When insufficient carbohydrate is consumed, the body is forced to make glucose from proteins—not a healthy change Chapter 4 focuses on carbohydrates

Lipids dissolve in certain chemical solvents (e.g., ether and benzene) but not in

water In this book, the more familiar terms fats and oils will generally be used,

rather than lipids Generally, fats are lipids that are solid at room temperature, and oils are lipids that are liquid at room temperature We obtain fats and oils from animal and plant sources Animal fats, such as butter or lard, are solid at room tem-perature Plant oils, such as corn or olive oil, tend to be liquid at room temperature

cell The structural basis of plant and animal organization Cells have the ability to take up compounds from and excrete compounds into their surroundings.

bond A linkage between two atoms, such as that formed by the sharing of electrons.

fiber Substances in plant foods not digested by the processes that take place in the human stomach or small intestine These add bulk to feces Fiber naturally found in foods is also

called dietary fiber.

Nutrient Classes That Provide Energy

Nutrient Classes That Promote Growth, Development, and Maintenance Nutrient Classes That Regulate Body Processes

1.3 What Are the Classes and Sources

of Nutrients?

To begin the study of nutrition, let’s start with an overview of the six classes of

nutrients You are probably already familiar with the terms carbohydrates,

lipids (fats and oils), proteins, vitamins, and minerals These nutrients, plus

water, make up the six classes of nutrients found in food.

Nutrients can then be assigned to three functional categories: (1) those that

primar-ily provide us with calories to meet energy needs (expressed in kilocalories [kcal]);

(2) those important for growth, development, and maintenance; and (3) those that

act to keep body functions running smoothly Some function overlap exists among

macronutrient A nutrient needed in gram quantities in a diet.

micronutrient A nutrient needed in milligram or microgram quantities in

a diet.

simple sugar Carbohydrate composed

of only one (monosaccharide) or two (disaccharide) sugar units.

complex carbohydrate Carbohydrate composed of many sugar units (poly- saccharide) Examples include glyco- gen, starch, and fiber.

starch A complex carbohydrate made

of multiple units of glucose attached together in a form the body can

digest.

used for cooking and that water is then discarded Minerals are critical players in nervous system functioning, water balance, structural (e.g., skeletal) systems, and many other cellular processes but produce no calories as such for the body.

The 16 or more essential minerals required in the diet for good health are divided

into two groups: major minerals and trace minerals because dietary needs and

con-centrations in the body vary enormously If daily needs are less than 100 milligrams, the mineral is classified as a trace mineral; otherwise, it is a major mineral Miner-als that function based on their electrical charge when dissolved in water are also

called electrolytes; these include sodium, potassium, and chloride Many major

minerals are found naturally in dairy products and fruits, whereas many trace erals are found in meats, poultry, fish, and nuts Minerals are covered in Chapter 9

min-WATER

Water makes up the sixth class of nutrients Although sometimes overlooked as a nutrient, water (chemically, H2O) has numerous vital functions in the body It acts

as a solvent and lubricant, as a vehicle for transporting nutrients and waste, and

as a medium for temperature regulation and chemical processes For these reasons, and because the human body is approximately 60% water, the average man should consume about 3 liters—equivalent to 3000 grams or about 13 cups—of water and/or other fluids every day Women need closer to 2200 grams or about 9 cups per day Fluid needs vary widely, however, based on differences in body mass and environmental conditions Because thirst is a late sign of dehydration, urine color can be used as another measure of hydration status Urine color should be no more yellow than lemonade

Water is not only available from the obvious sources, but it is also the major ponent in some foods, such as many fruits and vegetables (e.g., lettuce, grapes, and

com-melons) The body even makes some water as a by-product of metabolism Water

is examined in detail in Chapter 9

OTHER IMPORTANT COMPONENTS IN FOOD

Another group of compounds in foods from plant sources, especially within the

fruit and vegetable groups, is what scientists call phytochemicals Although these

plant components are not considered essential nutrients in the diet, many of these substances provide significant health benefits Considerable research attention is focused on various phytochemicals in reducing the risk for certain diseases For example, evidence from animal and laboratory studies indicates that compounds in blueberries and strawberries prevent the growth of certain cancer cells Although certain phytochemicals are now available as dietary supplements, research sug-gests that their health benefits are best obtained through the consumption of whole foods Foods with high phytochemical content are sometimes called “superfoods”

because of the health benefits they are thought to confer There is no legal

defini-tion of the term superfood, however, and there is concern that it is being overused in

marketing certain foods Table 1-3 lists some noteworthy phytochemicals with their common food sources Tips for boosting the phytochemical content of your diet will

be discussed in Chapter 2

Some related compounds under study are also found in animal products, such

as sphingolipids (meat and dairy products) and conjugated linoleic acid (meat and cheese) These are not phytochemicals per se because they are not from plant sources, but they have been shown to have health benefits

SOURCES OF NUTRIENTS

Now that we know the six classes of nutrients, it is important to understand that the quantities of the various nutrients that people consume in different foods vary widely On a daily basis, we consume about 500 grams, or about 1 pound, of

inorganic Any substance lacking

car-bon atoms car-bonded to hydrogen atoms

in the chemical structure.

electrolytes Substances that separate into ions in water and, in turn, are able to conduct an electrical current These include sodium, chloride, and potassium.

solvent A liquid substance in which

other substances dissolve.

metabolism Chemical processes in the body by which energy is provided in useful forms and vital activities are sustained.

phytochemical A chemical found in plants Some phytochemicals may con- tribute to a reduced risk of cancer or cardiovascular disease in people who consume them regularly.

To promote heart health, most people would benefit from using more plant oils in place of solid fats (see Chapter 5)

Certain fats are essential nutrients that must come from our diet These key fats that the body cannot produce, called essential fatty acids, perform several impor-tant functions in the body: they help regulate blood pressure and play a role in the synthesis and repair of vital cell parts However, we need only about 4 table-spoons of a common plant oil (such as canola or soybean oil) each day to supply these essential fatty acids A serving of fatty fish, such as salmon or tuna, at least twice a week is another healthy source of fats The unique fatty acids in these fish complement the healthy aspects of common vegetable oils This will be explained

in greater detail in Chapter 5, which focuses on lipids

PROTEINS

Proteins are the main structural material in the body For example, proteins tute a major part of bone and muscle; they are also important components in blood,

consti-body cells, enzymes, and immune factors Proteins can also provide calories for the

body—on average, 4 kcal per gram Typically, however, the body uses little protein

for the purpose of meeting daily calorie needs Proteins are formed when amino

acids are bonded together Some of these are essential nutrients.

Protein in our diet comes from animal and plant sources The animal products meat, poultry, fish, dairy products, and eggs are significant sources of protein in most diets Beans, grains, and some vegetables are good plant protein sources and are important to include in vegetarian diets

Most North Americans eat up to two times as much protein as the body needs

to maintain health This amount of extra protein in the diet reflects the standard of living and the dietary habits of most North Americans It is generally not harmful for healthy persons with no evidence of heart or kidney disease, diabetes, or fam-ily history of colon cancer or kidney stones The excess is used for calorie needs and carbohydrate production but ultimately can be converted to and stored as fat

Chapter 6 focuses on proteins

VITAMINSThe main function of vitamins is to enable many chemical reactions to occur in

the body Some of these reactions help release the energy trapped in carbohydrates, lipids, and proteins Remember, however, that vitamins themselves contain no usable calories for the body

The 13 vitamins are divided into two groups: four are fat-soluble because they dissolve in fat (vitamins A, D, E, and K); nine are water-soluble because

they dissolve in water (the B vitamins and vitamin C) The two groups of vitamins have different sources, functions, and characteristics Water-soluble vitamins are found mainly in fruits and vegetables, whereas dairy products, nuts, seeds, oils, and breakfast cereals are good sources of fat-soluble vitamins Cooking destroys water-soluble vitamins much more readily than it does fat-soluble vitamins Water- soluble vitamins are also excreted from the body much more readily than are fat-soluble vitamins Thus, the fat-soluble vitamins, especially vitamin A, have the ability to accumulate in excessive amounts in the body, which then can lead to tox-icity Vitamins are discussed in Chapter 8

MINERALSMinerals are structurally simple, inorganic substances that do not contain carbon

atoms Minerals such as sodium and potassium typically function independently

in the body, whereas minerals such as calcium and phosphorus combine to tion in tissue, such as bone mineral Because of their simple structure, minerals are not destroyed during cooking, but they can still be lost if they dissolve in the water

func-enzyme A compound that speeds the

rate of a chemical reaction but is not

altered by the reaction Almost all

enzymes are proteins (some are made

of genetic material).

amino acid The building block for

proteins containing a central carbon

atom with nitrogen and other atoms

attached.

chemical reaction An interaction

between two chemicals that changes

both chemicals.

▲ Salmon is a fatty fish that is a healthy

source of essential fatty acids.

Chapter 1: Nutrition, Food Choices, and Health 13

used for cooking and that water is then discarded Minerals are critical players in nervous system functioning, water balance, structural (e.g., skeletal) systems, and many other cellular processes but produce no calories as such for the body

The 16 or more essential minerals required in the diet for good health are divided

into two groups: major minerals and trace minerals because dietary needs and

con-centrations in the body vary enormously If daily needs are less than 100 milligrams, the mineral is classified as a trace mineral; otherwise, it is a major mineral Miner-als that function based on their electrical charge when dissolved in water are also

called electrolytes; these include sodium, potassium, and chloride Many major

minerals are found naturally in dairy products and fruits, whereas many trace erals are found in meats, poultry, fish, and nuts Minerals are covered in Chapter 9

min-WATER

Water makes up the sixth class of nutrients Although sometimes overlooked as a nutrient, water (chemically, H2O) has numerous vital functions in the body It acts

as a solvent and lubricant, as a vehicle for transporting nutrients and waste, and

as a medium for temperature regulation and chemical processes For these reasons, and because the human body is approximately 60% water, the average man should consume about 3 liters—equivalent to 3000 grams or about 13 cups—of water and/or other fluids every day Women need closer to 2200 grams or about 9 cups per day Fluid needs vary widely, however, based on differences in body mass and environmental conditions Because thirst is a late sign of dehydration, urine color can be used as another measure of hydration status Urine color should be no more yellow than lemonade

Water is not only available from the obvious sources, but it is also the major ponent in some foods, such as many fruits and vegetables (e.g., lettuce, grapes, and

com-melons) The body even makes some water as a by-product of metabolism Water

is examined in detail in Chapter 9

OTHER IMPORTANT COMPONENTS IN FOOD

Another group of compounds in foods from plant sources, especially within the

fruit and vegetable groups, is what scientists call phytochemicals Although these

plant components are not considered essential nutrients in the diet, many of these substances provide significant health benefits Considerable research attention is focused on various phytochemicals in reducing the risk for certain diseases For example, evidence from animal and laboratory studies indicates that compounds in blueberries and strawberries prevent the growth of certain cancer cells Although certain phytochemicals are now available as dietary supplements, research sug-gests that their health benefits are best obtained through the consumption of whole foods Foods with high phytochemical content are sometimes called “superfoods”

because of the health benefits they are thought to confer There is no legal

defini-tion of the term superfood, however, and there is concern that it is being overused in

marketing certain foods Table 1-3 lists some noteworthy phytochemicals with their common food sources Tips for boosting the phytochemical content of your diet will

be discussed in Chapter 2

Some related compounds under study are also found in animal products, such

as sphingolipids (meat and dairy products) and conjugated linoleic acid (meat and cheese) These are not phytochemicals per se because they are not from plant sources, but they have been shown to have health benefits

SOURCES OF NUTRIENTS

Now that we know the six classes of nutrients, it is important to understand that the quantities of the various nutrients that people consume in different foods vary widely On a daily basis, we consume about 500 grams, or about 1 pound, of

inorganic Any substance lacking

car-bon atoms car-bonded to hydrogen atoms

in the chemical structure.

electrolytes Substances that separate into ions in water and, in turn, are able to conduct an electrical current These include sodium, chloride, and potassium.

solvent A liquid substance in which

other substances dissolve.

metabolism Chemical processes in the body by which energy is provided in useful forms and vital activities are sustained.

phytochemical A chemical found in plants Some phytochemicals may con- tribute to a reduced risk of cancer or cardiovascular disease in people who consume them regularly.

protein, fat, and carbohydrate In contrast, the typical daily mineral intake totals about 20 grams (about 4 teaspoons), and the daily vitamin intake totals less than

300 milligrams (1/15 of a teaspoon) Although we require a gram or so of some minerals, such as calcium and phosphorus, we need only a few milligrams or less of other minerals each day For example, we need about 10 milligrams of zinc per day, which is just a few specks of the mineral

The nutrient content of the foods we eat also differs from the nutrient tion of the human body This is because growth, development, and later mainte-nance of the human body are directed by the genetic material (DNA) inside body cells This genetic blueprint determines how each cell uses the essential nutrients to perform body functions These nutrients can come from a variety of sources Cells are not concerned about whether available amino acids come from animal or plant sources The carbohydrate glucose can come from sugars or starches The food that you eat provides cells with basic materials to function according to the directions

composi-supplied by the genetic material (genes) housed in body cells Genetics and

nutri-tion will be discussed in Chapter 3

1 What are the six classes of nutrients?

2 What are the three general functions of nutrients in the body?

CONCEPT CHECK 1.3

✔

genes A specific segment on a

chro-mosome Genes provide the blueprints

for the production of all body proteins.

Food Sources Phytochemical

Orange, red, and yellow fruits and vegetables (egg yolks

Cruciferous vegetables (broccoli, cabbage, kale) Indoles

Soybeans, other legumes, cucumbers, other fruits and

Citrus fruit, onions, apples, grapes, red wine, tea,

Blueberries, strawberries, raspberries, grapes, apples,

Red, blue, and purple plants (blueberries, eggplant) Anthocyanosides

▲ Blueberries are sometimes considered

“superfoods” because they are rich in

health-promoting phytochemicals.

Chapter 1: Nutrition, Food Choices, and Health 15

1.4 What Math Concepts Will Aid Your

Study of Nutrition?

CALORIES

We obtain the energy we need for involuntary body functions and voluntary

physi-cal activity from various physi-calorie sources: carbohydrates (4 kphysi-cal per gram), fats (9 kphysi-cal

per gram), and proteins (4 kcal per gram) Foods generally provide more than one

calorie source Plant oils, such as soybean or canola oil, are one exception; these are

100% fat at 9 kcal per gram

Alcohol is also a potential source of calories, supplying about 7 kcal per gram It

is not considered an essential nutrient, however, because it is not required for human

function Still, alcoholic beverages, such as beer—also rich in carbohydrate—are a

contributor of calories to the diets of many adults

The body releases the energy from the chemical bonds in carbohydrate, protein,

and fat (and alcohol) in order to:

• Build new compounds

• Perform muscular movements • Promote nerve transmission. • Maintain electrolyte balance within cells

Chapter 7 describes how that energy is released from the chemical bonds in

energy-yielding nutrients and then used by body cells to support the processes just

described

The energy in food is often expressed in terms of calories on food labels As

defined earlier, a calorie is the amount of heat energy it takes to raise the

tempera-ture of 1 gram of water 1 degree Celsius (18C, centigrade scale) (Chapter 7 has a

diagram of the bomb calorimeter that can be used to measure calories in foods.) A

calorie is a tiny measure of heat, so food energy is more conveniently expressed in

terms of the kilocalorie (kcal), which equals 1000 calories (If the “c” in calories is

capitalized, this also signifies kilocalories.) A kcal is the amount of heat energy it

takes to raise the temperature of 1000 grams (1 liter) of water 18C The abbreviation

kcal is used throughout this book On food labels, the word calorie (without a capital

“C”) is also used loosely to mean kilocalorie Any values given on food labels in

calo-ries are actually in kilocalocalo-ries (Fig. 1-4) A suggested intake of 2000 calocalo-ries per day

on a food label is technically 2000 kcal

CALCULATING CALORIES

Use the 4-9-4 estimates for the calorie content of carbohydrate, fat, and protein

introduced over the last few pages to determine calorie content of a food Consider

these foods:

alcohol Ethyl alcohol or ethanol (CH3CH2OH) is the compound in alco- holic beverages.

7 kcal per gram

▲ Calorie content of energy nutrients and alcohol The weights illustrate their relative energy potential per gram.

8-ounce Piña Colada

Carbohydrate 57 grams 3 4 5 228 kcal

FIGURE 1-4 ▲ Use the nutrient values on the Nutrition Facts panel to calculate calorie content of a food Based on

carbohydrate, fat, and protein content, a serving of this food (Whole Wheat Bread) contains 81 kcal ([15 3 4] 1 [1 3 9] 1 

[3 3 4] 5 81) The label lists 80, suggesting that the calorie value was rounded down.

Nutrition Facts

Serving Size 1 slice (36g) Servings Per Container 19

Amount Per Serving

Calories 80 Calories from Fat 10

Vitamin A 0% Vitamin C 0% Calcium 0% Iron 4%

*Percent Daily Values (DV) are based on a 2,000

** Intake of trans fat should be as low as possible.

calorie diet Your daily values may be higher or lower depending on your calorie needs:

Calories: 2,000 2,500 Total Fat Less than 65g 80g Sat Fat Less than 20g 25g Cholesterol Less than 300mg 300mg Sodium Less than 2,400mg 2,400mg Total Carbohydrate 300g 375g Dietary Fiber 25g 30g

I N G R E D I E N T S : WHOLE WHEAT, WATER, ENRICHED WHEAT FLOUR [FLOUR, MALTED BARLEY, NIACIN, REDUCED IRON, THIAMINE MONONITRATE (VITAMIN B1) AND RIBOFLAVIN (VITAMIN B2)], CORN SYRUP, PAR- TIALLY HYDROGENATED COTTONSEED OIL, SALT, YEAST.

WHOLE WHEAT BREAD

Joe ate 15% of the adult Recommended Dietary Allowance for iron (RDA  5 

8 milligrams) at lunch How many milligrams did he eat?

0.15 3 8 milligrams 5 1.2 milligrams

You can also use the 4-9-4 estimates to determine what portion of total calorie intake

is contributed by the various calorie-yielding nutrients Assume that one day you consume 290 grams of carbohydrates, 60 grams of fat, and 70 grams of protein This consumption yields a total of 1980 kcal ([290 3 4] 1 [60 3 9] 1 [70 3 4] 5 1980)

The percentage of your total calorie intake derived from each nutrient can then be determined:

% of kcal as carbohydrate 5 (290 3 4) 4 1980 5 0.59 (3 100 5 59%)

% of kcal as fat 5 ( 60 3 9) 4 1980 5 0.27 (3 100 5 27%)

% of kcal as protein 5 ( 70 3 4) 4 1980 5 0.14 (3 100 5 14%)Check your calculations by adding the percentages together Do they total 100%?

PERCENTAGES

You will use a few mathematical concepts in studying nutrition Besides ing addition, subtraction, multiplication, and division, you need to know how to calculate percentages and convert English units of measurement to metric units

perform-The term percent (%) refers to a part of the total when the total represents 100 parts

For example, if you earn 80% on your first nutrition examination, you will have answered the equivalent of 80 out of 100 questions correctly This equivalent also could be 8 correct answers out of 10; 80% also describes 16 of 20 (16/20 5 0.80 or 80%) The decimal form of percents is based on 100% being equal to 1.00 It is difficult

to succeed in a nutrition course unless you know what a percentage means and how

to calculate one Percentages are used frequently when referring to menus and ent composition The best way to master this concept is to calculate some percent-ages Some examples follow:

What is 6% of 45? 6% 5 0.06, so 0.06 3 45 5 2.7 What percent of 99 is 3? 3/99 5 0.03 or 3% (0.03 3 100)

Chapter 1: Nutrition, Food Choices, and Health 17

1.5 How Do We Know What We Know

About Nutrition?

How do we know what we know about nutrient needs? In a word, research Like

other sciences, the research that sets the foundation for nutrition knowledge has

developed using the scientific method, a testing procedure designed to detect and

eliminate error

THE SCIENTIFIC METHOD

The first step of the scientific method is the observation of a natural phenomenon

(Fig. 1-5) Scientists then suggest possible explanations, called hypotheses, about

its cause At times, historical events have provided clues to important relationships

in nutrition science, such as the link between the need for vitamin C and the

devel-opment of the disease scurvy (see Chapter 8) Another approach is for scientists

to study diet and disease patterns among various populations, a research method

called epidemiology.

Thus, hypotheses about the role of diet in various health problems can be

suggested by historical and epidemiological findings Proving the role of

particu-lar dietary components, however, requires controlled experiments The data

gath-ered from experiments may either support or refute each hypothesis If the results

of many experiments support a hypothesis, scientists accept the hypothesis as a

theory Often, the results from one experiment suggest a new set of questions.

The most rigorous type of controlled experiment follows a randomized,

double-blind, placebo-controlled study design In this type of study, a group of participants—

the experimental group—follows a specific protocol (e.g., consuming a certain food

hypotheses Tentative explanations by

a scientist to explain a phenomenon.

scurvy The deficiency disease that results after a few weeks to months of consuming a diet that lacks vitamin C; pinpoint sites of bleeding on the skin are an early sign.

epidemiology The study of how disease rates vary among different population groups.

theory An explanation for a enon that has numerous lines of evidence to support it.

phenom-double-blind study An experimental design in which neither the partici- pants nor the researchers are aware of each participant’s assignment (test or placebo) or the outcome of the study until it is completed An independent third party holds the code and the data until the study has been completed.

THE METRIC SYSTEM

The basic units of the metric system are the meter, which indicates length; the

gram, which indicates weight; and the liter, which indicates volume Appendix F

in this textbook lists conversions from the metric system to the English system

(pounds, feet, and cups) and vice versa Here is a brief summary:

A gram (g) is about 1/30 of an ounce (28 grams to the ounce)

5 grams of sugar or salt is about 1 teaspoon

A pound (lb) weighs 454 grams

A kilogram (kg) is 1000 grams, equivalent to 2.2 pounds

To convert your weight to kilograms, divide it by 2.2

A 154-pound man weighs 70 kilograms (154/2.2 5 70)

A gram can be divided into 1000 milligrams (mg) or 1,000,000 micrograms (mg or mcg)

10 milligrams of zinc (approximate adult need) would be a few grains of zinc

Liters are divided into 1000 units called milliliters (ml)

One teaspoon equals about 5 milliliters (ml), 1 cup is about 240 milliliters, and

1 quart (4 cups) equals almost 1 liter (L) (0.946 liter to be exact)

A centimeter is 1/100 of a meter 2.54 centimeters equals 1 inch

If you plan to work in any scientific field, you will need to learn the metric

sys-tem For now, remember that a kilogram equals 2.2 pounds, an ounce weighs 28 grams,

2.54 centimeters equals 1 inch, and a liter is almost the same as a quart In addition, know

the fractions that the following prefixes represent: micro (1/1,000,000), milli (1/1000),

centi (1/100), and kilo (1000).

1 What are the energy (calorie) values for each of the “energy nutrients”?

CONCEPT CHECK 1.4

✔