Chapter 1
Chapter Summary
The Nutrients in Foods
Most foods are mostly water, but they also contain other parts that, with water, comprise the
nutrients in foods. Many of these nutrients are essential (about 40) while others are nonessential.
Energy is derived from carbohydrates, fats, and proteins (and alcohol). The six classes of
nutrients are: carbohydrates, fats, proteins, vitamins, minerals, and water. The energy from
foods is used to perform work (internal or external) or to generate heat. Excess energy is stored
as fat.
Vitamins and minerals do not supply energy, but are used to regulate many (most) bodily
functions. Vitamins are divided into two classes, fat soluble (A, D, E, and K) and water soluble
(B vitamins and C).
Minerals also perform many regulatory functions in the body. Some form part of the body’s
structures (bone minerals).
Water, a crucial nutrient, comprises about 60% of body weight. Water acts as a medium for all
cellular activity. Additionally, all gasses, nutrients, and wastes are transported through an
aqueous solution. About two to three quarts (liters) of water are lost, and must be replaced,
daily.
Nutrition and Health Promotion
Nutrition is complex. It is the relationship between food and the body and the study of what
happens to health, development, and performance when the body receives too few, too many,
or the wrong balance of nutrients. To enjoy the best of health you must be sure to select foods
that contain all the nutrients you need without an excess of calories. Many of the leading
causes of death have been linked to diet.
A National Agenda for Improving Nutrition and Health
Researchers have provided a dramatic demonstration of how personal choices affect health. In
effect, you can make yourself younger or older by the way you choose to live. Recognizing diet’s
vital influence on health, the U.S. Department of Health and Human Services’ Healthy People
2020 Initiative provides objectives for reducing disease risk through diet.
A basic understanding of nutrition can go a long way in helping protect health—from trimming
fat and calories from supersized fast-food meals to stocking cupboards at home for healthful
eating. Food choices affect health profoundly. Unwise choices can contribute to the increasing
problem of overweight and obesity seen among Americans of all ages.
Understanding Our Food Choices
The reasons underlying individual food choices are as many and varied as the individuals
themselves. A person may eat in response to hunger or appetite, choosing certain foods
because of advertising, personal preference, habit or cultural tradition, social pressure, values
or personal beliefs, availability, economy, convenience, psychological benefits, or nutritional
value.
How Do You Tell If It’s Nutrition Fact or Nutrition Fiction?
Health fraud, or quackery, robs Americans of more that $30 billion annually through
worthless, and often harmful, products. Fortunately, many of the pseudoscientific claims in
print are harmless. However, some fads and frauds are not. Among those most likely to be
taken in and harmed by nutrition fads and frauds are the elderly, people seeking quick weight
loss schemes, and people with chronic diseases or nonspecific medical conditions.
Consumers can learn strategies to help judge the validity of sources of nutrition information.
Many professional organizations provide guidance in judging their quality and reliability.
Chapter 2
Chapter Summary
The ABCs of Eating for Health
Six concepts to remember when planning a healthy diet are adequacy, balance, calorie control,
moderation, variety, and nutrient density.
Diet Planning Principles:
• Adequacy – enough of each type of food
• Balance – not too much of any type of food
• Calorie control – not too many or too few calories
• Moderation – not too much fat, salt, or sugar
• Variety – as many different foods as possible
Nutrient Recommendations
The DRI (Dietary Reference Intakes) represent suggested nutrient intakes for healthy people in
the United States and Canada. Other nations have their own similar standards. The DRI
include the RDA (Recommended Dietary Allowances), AI (Adequate Intakes), EAR (Estimated
Average Requirements), UL (Tolerable Upper Intake Levels), EER (Estimated Energy
Requirements), and AMDR (Acceptable Macronutrient Distribution Ranges). The AMDR provide
acceptable ranges for energy composition for a balanced diet.
The Challenge of Dietary Guidelines
The dietary guidelines provide information for leading a healthy lifestyle that includes a
nutritious diet and adequate activity. The key recommendations include:
•
Balancing calories to manage weight
•
Foods and food components to reduce – sodium (<2300 mg/day; <1500 mg for those at risk
for hypertension), saturated fat (<10% calories), cholesterol (<300 mg/day), trans fat (low as
possible), empty calories (from solid fats/added sugars), refined grains, alcohol
•
Foods and nutrients to increase – vegetables (especially dark green, red, orange, beans,
peas), fruits, whole grains (≥50% of grain intake), fat-free/low-fat dairy, seafood, oils (in
place of solid fats), potassium, fiber, calcium, vitamin D
•
Building healthy eating patterns – proper calorie intake, food safety
Introducing the MyPlate Diet-Planning Tool
USDA’s MyPlate incorporates the principles of wise diet planning—adequacy, balance, calorie
control, moderation, and variety—and is flexible enough to allow for individual preferences. By
using guidelines that help distinguish nutritious foods from their less nutritious counterparts
and being mindful about portion sizes, you can be a savvy diner in almost any situation.
Using MyPlate to Achieve a Healthy Lifestyle. The new MyPlate emphasizes healthful
choices designed to fit more easily into the personal dietary choices of all people who use the
USDA’s website, www.ChooseMyPlate.gov. Unlike the previous graphic, MyPlate represents the
proportions of food groups to eat in a way that is easy for consumers to visualize. MyPlate
emphasizes six components of health and diet. These include:
•
•
•
•
Activity,
Variety – be sure to include a variety of groups as well as a variety of choices within each
group,
Proportionality – vegetables and fruits should fill up at least half the plate at each meal,
Moderation – emphasizes the need to limit empty calories from solid fats and added sugars,
•
•
Personalization – allows each person to figure out how much of each food group to eat to
obtain the right amounts of energy (calories) and nutrients, and
Gradual Improvement – provides steps to help each person make better choices to improve
the diet.
Use the Simplicity of MyPlate to Build a Healthful Diet. To determine how much to eat to
maintain weight:
•
•
•
Step 1: Estimate your daily energy needs using Table 2-4 or the online tool
Step 2: Build your daily eating plan using the MyPlate plan for your calorie level (Table 2-5)
Step 3: Let MyPlate guide your food choices on a daily basis
You must learn to recognize appropriate portion sizes in order to follow the eating plan. You
should choose primarily nutrient-dense foods from each group and include heart-healthy oils
(while avoiding solid fats) in order to ensure nutritional adequacy of the diet without exceeding
calorie needs.
Using MyPlate to Meet Nutrient Needs. Vitamins, minerals, and fiber come mainly from
grains, fruits, vegetables, and dairy (non- or low-fat) groups. Nutrient-dense, low-saturated fat
protein foods provide protein, iron, and zinc. Heart-healthy oils provide vitamin E and essential
fats.
Using MyPlate to Moderate Energy Intakes. Table 2-7 includes tips for choosing nutrientdense—rather than energy-dense—foods from each group, such as whole foods, especially
plant foods and non-fat dairy.
Gaining Calorie Control: The Daily Limit for Empty Calories. If you are able to obtain all
essential nutrients without meeting your energy needs, the remnant of your calorie budget is
termed the daily limit for empty calories, and may be “spent” on either nutritious foods or
empty calories, such as those from added sugars, added fats, foods that are not in their most
nutrient-dense form (such as whole milk rather than non-fat milk or sweetened rather than
non-sweetened applesauce), or alcohol.
More Tools for Diet Planning
Food Labels. The Nutrition Facts panel of food labels is another important tool you can use to
eat healthfully. Food labels help you easily compare similar products. The label provides
information about nutrients, addressing present health concerns: calories, calories from fat,
total fat, saturated fat, trans fat, cholesterol, sodium, total carbohydrate, dietary fiber, sugars,
protein, vitamin A, vitamin C, calcium, and iron. Foods carrying nutrient content or health
claims must meet strict requirements governing the use of such claims.
Exchange Lists. The food exchange lists (originally designed for diabetics) provide a method for
making choices within a particular good group. The list describes what a standard serving is
and how many servings are contained in the food a person is choosing. The exchange lists
allow people to determine how many servings from a group are contained in the food they eat if
it does not fit easily into an exact serving size. It is particularly useful for people who are
concerned with diet adequacy and caloric content.
A Tapestry of Cultures and Cuisines
The Spotlight feature examines some of the more prevalent food practices in mainstream
America to see how they originated and how they fit into a healthful eating plan. Among these
cultures and cuisines are Mexican, Chinese, Italian, Indian, African American, and Jewish
American.
Many nutrition experts advocate adopting aspects of the Mediterranean diet, in particular: Get
daily physical activity and eat an abundance of fruits, vegetables, whole grains, and legumes
combined with moderate amounts of dairy products and relatively smaller amounts of meat,
poultry, and fish.
Chapter 3 Summary
Introduction to the Human Body
The body’s millions of cells must be supplied with energy, oxygen, water, and essential
nutrients (which are obtained from foods) in order to survive. These cells are part of the body’s
overall organization: body systems are composed of organs, which are composed of tissues,
which are composed of cells.
The Digestive System
The digestive system is responsible for moving food through the body (gastrointestinal tract),
mixing it with digestive juices and enzymes, digesting it, absorbing water and nutrients from it,
and distributing the absorbed water/nutrients into the circulatory system.
The Gastrointestinal Tract. The gastrointestinal (GI) tract has a protective outer layer called
the mesentery, an inner layer called the mucosa, and layers of longitudinal and circular
muscles in between. The muscles move food along and mix it with secretions, while the mucosa
secrete substances such as enzymes and protective mucus.
In the mouth, food is subjected to mechanical digestion (mastication), exposed to the enzyme
salivary amylase, and formed into a bolus, which is swallowed and travels down the esophagus
to the stomach via peristalsis. The stomach stores food that is waiting to be processed, mixes
food with gastric secretions (thick and thin mucus, intrinsic factor, and hydrochloric acid) to
form chyme, and releases the chyme into the small intestine at an appropriate rate.
The small intestine is the principal organ of digestion and absorption. As chyme moves along
the small intestine, bile emulsifies fat, and pancreatic and intestinal enzymes further break
down food constituents into glucose, glycerol, fatty acids, amino acids, etc. The multi-folded
surface of the small intestine with its millions of villi provides a large area so that the cells of
the mucosa can absorb these products of digestion into the lymph (fats and fat-soluble
vitamins) and blood (carbohydrates, proteins, water-soluble vitamins, and minerals).
The remains of the chyme pass through the ileocecal valve into the large intestine (colon),
which absorbs additional minerals and water and forms the chyme into a paste (fecal material)
which is periodically excreted. Bacteria that live in the large intestine digest some fiber and
release flatus and vitamin K.
Accessory Organs of Digestion. The liver—a busy metabolic organ—produces bile that is
secreted into the gallbladder, where it is stored and concentrated. The gallbladder then releases
the bile into the small intestine via the common bile duct when signaled by the hormone
cholecystokinin. The pancreas performs endocrine functions—secretion of the blood glucoseregulating hormones, insulin and glucagon, into the blood—and exocrine functions—secretion
of digestive enzymes into the small intestine. Pancreatic enzymes break down carbohydrates,
proteins, and fats.
Metabolism
Newly-absorbed water-soluble nutrients are delivered from the GI tract to the liver for
processing (into glucose, glycogen, and fat) via a large vein. Fat-soluble nutrients absorbed into
lymph travel throughout the body (as chylomicrons) and deliver fats to body cells before
arriving at the liver for processing (into lipoproteins and other products). The products of liver
metabolism (glucose, lipoproteins, and amino acids) are then released into the blood and
utilized by body cells; leftover fat is stored in fat cells.
The body stores surplus energy in the form of glycogen (in the liver and muscles) and fat (in fat
cells throughout the body) so that energy is available for body cells between meals. Amino acids
are available from a liver and blood pool; many vitamins are stored in the liver and fat cells;
and calcium, sodium, and other minerals stored in bone can be released to maintain blood
levels.
Two major types of energy metabolism are catabolism and anabolism. Catabolic reactions
usually release energy, and involve breaking down compounds into smaller units (e.g., glycogen
to glucose, fat into glycerol and fatty acids). Anabolic reactions usually require energy, and
involve synthesizing compounds from smaller units (e.g., glycogen from glucose, fat from
glycerol and fatty acids).
Gut Feelings: Common Digestive Problems
The Spotlight feature discusses the causes, symptoms, and alleviation strategies for hiccups,
intestinal gas, lactose intolerance, constipation, and hemorrhoids.
Chapter 4 Summary
The Body’s Need for Carbohydrates
The primary role of carbohydrates is to provide energy for the body. In fact, the brain and
nervous system rely almost exclusively on carbohydrates (in the form of blood glucose) for their
energy needs. Since the body cannot manufacture carbohydrates, they must be supplied
through the diet. Additionally, carbohydrates contribute to certain body structures. Therefore,
carbohydrates are essential to life.
Carbohydrates Basics
At least half our food energy is derived from carbohydrate, principally from starch but also
from the simple sugars. Carbohydrates are classified as complex carbohydrates or simple
carbohydrates. Although carbohydrate bashing is a popular pastime, it is excess calories that
are fattening. If you are in the habit of serving carbohydrate-rich foods laden with fat, it is the
fat, not the carbohydrate, that raises the calorie count the most.
The Simple Carbohydrates: Monosaccharides and Disaccharides
The most common of the single sugars is glucose; the sweetest, fructose. Galactose is the third.
Each of the three double sugars (sucrose, lactose, and maltose) contains a molecule of glucose
paired with fructose, galactose, or another glucose. Sucrose or table sugar contains both
glucose and fructose. The source of energy from concentrated sweets such as sodas, cakes, and
candy is sucrose (or a blend of fructose and glucose, the same two molecules that are joined in
sucrose). Lactose, or milk sugar, is made up of a molecule each of glucose and galactose.
Lactose is easily digested except by people with lactose intolerance. The third double sugar,
maltose, is made up of two molecules of glucose.
We are encouraged to use the concentrated sweets—the so-called empty-calorie foods—only in
moderation, so as not to displace needed nutrients. The same does not apply to the naturally
occurring sugars found in fruits and dairy products.
The Complex Carbohydrates: Starch
The polysaccharides starch, glycogen, and fiber are composed of chains of glucose units.
Starch is the storage form of glucose in the plant. Sources of starch in the diet include seeds,
grains, and starchy vegetables. Dietary fiber is indigestible by humans.
Whole-grain breads are produced with flour made from the germ, bran, and endosperm of the
wheat kernel, whereas enriched breads contain flour made from the endosperm only.
The Complex Carbohydrates: Fiber
Researchers note the beneficial effects of both insoluble and soluble fibers in the diet for
reducing the risk of diseases such as atherosclerosis, colon cancer (possibly), diabetes,
diverticulosis, and obesity. It is important to eat a variety of high-fiber foods to reap the
benefits derived from both types of fiber.
Guidelines for Choosing Carbohydrates
It is recommended that people consume 45%-65% of their total calories from carbohydrates,
preferably from complex carbohydrates such as whole grains. The Dietary Guidelines
recommend consuming enough fiber-rich foods to provide 14 g fiber per 1000 calories while
reducing the intake of calories from added sugars. The USDA’s MyPlate provides a framework
from which to select carbohydrates in the diet.
How the Body Handles Carbohydrates
Nutrition status affects our well-being even at the level of the body’s cells. The body strives to
maintain its blood glucose within a normal range for optimal health and functioning. The
hormones insulin and glucagon function to maintain normal blood glucose levels in the body.
Glycogen is made in the liver and muscles from excess glucose in the bloodstream. It can be
broken down by the liver to maintain a constant blood glucose level.
Hypoglycemia and Diabetes
The body normally deals with low blood sugar (hypoglycemia) by converting amino acids to
glucose and utilizing fat stores. True hypoglycemia results from excessive insulin secretion by
the pancreas, and manifests in symptoms of glucose deprivation to the brain—irritability,
weakness, dizziness, and rapid heartbeat.
Hyperglycemia (elevated blood sugar) is the hallmark of diabetes mellitus, a condition in which
the pancreas secretes little or no insulin (type 1) or the body cells resist insulin and do not
respond by taking up glucose from the blood (type 2). Diabetics are advised to consume a highcomplex carbohydrate diet similar to that prescribed for the population at large, but must
control their portions and eat on a schedule so as to maintain their blood glucose within the
recommended level. Type 1 diabetics (and some type 2 diabetics) must coordinate insulin
injections with meals to maintain blood glucose levels. Type 2 diabetes is associated with
obesity.
Sugar and Health
Many misconceptions about sugar (simple/refined sweeteners) abound. Perhaps the biggest
problem with sugar is that it is an “empty-calorie” food. That is, it contains calories and
virtually nothing else. If a person consumes a lot of sugar, it may certainly crowd out other
nutrient-dense foods, or may contribute to the over-consumption of total calories and therefore
obesity. Additionally, sugar has been linked to increases in dental caries (cavities). A judicious
diet includes some simple sweeteners, but no more than 10% of total calories from sugars
(hopefully).
Sweet Talk—Alternatives to Sugar
This chapter’s Spotlight feature answers questions regarding the many artificial and alternative
sweeteners available on the market today. The artificial sweeteners are nonnutritive sugar
replacements such as aspartame, saccharin, stevia, and sucralose. The alternative sweeteners,
which provide some energy, contain and include fructose and the sugar alcohols—including
sorbitol and xylitol. The FDA authorizes use of the health claim on food labels that sugar
alcohols do not promote tooth decay.
Chapter 5 Summary
A Primer on Fats
Lipids in the body function to maintain the health of the skin and hair; to protect body organs
from heat, cold, and mechanical shock; and to provide a continuous energy supply. The
breakdown of 1 pound of body fat supplies 3,500 calories to meet energy needs. In foods, fats
and oils act as a solvent for the fat-soluble vitamins and the compounds that give foods their
flavors and aromas.
A Closer View of Fats
About 95% of the lipids in the diet are triglycerides; the phospholipids and sterols make up the
other 5%. The fatty acids may be classified as saturated, monounsaturated, or
polyunsaturated. Many combinations of fatty acids are possible in fats and oils.
Linoleic acid (an omega-6 fatty acid) and linolenic acid (an omega-3 fatty acid) are the most
important of the polyunsaturated fatty acids in foods. The body is unable to synthesize them;
therefore, they are essential fatty acids. Deficiency symptoms of the essential fatty acids
include skin rash, and in children, poor growth. The essential fatty acids belong to families of
omega-3 and omega-6 fatty acids; non-essential omega-3 fatty acids such as EPA and DHA are
thought to be health-protective.
Characteristics of Fats in Foods
Solid fats (which are mostly animal in origin) have a high percentage of saturated or trans fats,
whereas liquid oils are mostly unsaturated. Food fats containing unsaturated fatty acids spoil
easily. Hydrogenation makes these acids less susceptible to spoilage; but in partial
hydrogenation, trans-fatty acids, which may have an adverse effect on health, are formed.
The Other Members of the Lipid Family: Phospholipids and Sterols
Phospholipids and a related molecule called lecithin are molecules consisting of fats (fatty
acids) combined with a phosphate atom. These molecules are used to build the walls of all of
the cells in our bodies. Additionally, they serve as emulsifiers that allow fat to be transported
back and forth through the cell membrane.
Sterols are fats that have been changed or altered within the body to perform certain functions.
Perhaps the best known sterol is cholesterol, found in the blood (as a fat transporter) and in
the cell walls. It is also the major constituent of bile, a substance stored in the gallbladder that
helps break down fats in the small intestine. Cholesterol is also found in the skin as a
precursor of vitamin D. Yet another use of sterols is in the production of the sex hormones
(estrogen and testosterone).
How the Body Handles Fat
During digestion, the triglycerides are emulsified by bile and then broken apart by enzymes to
monoglycerides, glycerol, and fatty acids, which then pass into the intestinal cells. After
absorption, all three classes of lipids are transported by lipoproteins in the body fluids.
“Good” versus “Bad” Cholesterol
Cholesterol is made in the body by the liver, and may be used to make bile, transported to body
tissues by LDL-cholesterol, or abnormally deposited in artery walls. It is thought that
circulating LDL first reacts with unstable oxygen to become oxidized LDL-cholesterol, and then
is engulfed by macrophages, which swell up with cholesterol (as foam cells), burst, and deposit
cholesterol debris on artery walls to form fatty streaks. These streaks develop into
atherosclerotic plaques.
HDL, on the other hand, predicts low heart disease risk (hence the term “good cholesterol”).
A diet high in saturated fat and cholesterol has been implicated as a causative factor in heart
disease. Authorities recommend that you choose a diet that is low in saturated fat and
cholesterol and moderate in total fat as a preventive measure:
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•
•
Keep fat intake within 20%-35% of total calories.
Eat no more than 10% of calories as saturated fat.
Limit daily cholesterol intake to no more than 300 milligrams.
Fat in the Diet
Foods that contain fat are found in the meat and milk groups and in fats themselves. Most of
the saturated fat found in the diet comes from meat and other animal fats. Organ meats,
shellfish, eggs, meats, and other animal fats contribute cholesterol to the diet. No plant
product contains cholesterol. Vegetable and fish oils generally contain more polyunsaturated
fats than do other animal fats.
Fat Can Be Healthy
The Mediterranean diet is rich in fruits, vegetables, grains, fish, and beans. It is high in
beneficial phytochemicals and naturally low in saturated fat because little meat and butter is
consumed. Olive oil contains heart-healthy, monounsaturated oleic acid, which helps keep
HDL high while lowering LDL and boasts a good omega-3 to omega-6 ratio. Other food sources
of protective omega-3 fats include oily coldwater fish, ground flaxseed, flaxseed and canola oils,
soy products, pecans, and walnuts; however plant sources are not as helpful as fish or algal
omega-3s.
The Trans Fatty Acid Controversy—Is Butter Better?
Research suggest that trans fats from margarine made with hydrogenated oils increase blood
LDL while lowering blood HDL. When hydrogens are added to unsaturated fatty acids, they
become more saturated and sometimes take on the trans configuration—with H atoms on
opposite sides of the point of unsaturation instead of side by side. Trans fats are found in any
food made with hydrogenated oils, such as shortening, baked goods, or commercially fried
foods. Since January 2006, trans fats (in grams) have been required to be listed on processed
food labels.
Despite the health effects of trans fats, butter is not preferable because its saturated fat also
raises LDL levels. Consumers should rely on the Nutrition Facts labels to choose heart-healthy
spreads and other foods.
Understanding Fat Substitutes
The present boom in both low-fat and fat-free products has to do with the country’s expanding
health consciousness. Manufacturers use several techniques to replace the fat in their
products, including the development of fat substitutes such as Simplesse and olestra.
Diet and Heart Disease
The Spotlight considers the relationship between nutrition and heart disease. The chapter
concludes with guidance for a heart-healthy lifestyle:
•
•
•
•
Achieve an overall healthy eating pattern. Consume a variety of fruits, vegetables, and grain
products, including whole grains; include low-fat milk products, fish, legumes, poultry, and
lean meats.
Achieve a healthy body weight.
Achieve a desirable cholesterol level.
Achieve a desirable blood pressure level.
Chapter 6 Summary
What Proteins Are Made Of
Proteins are composed of amino acids, which are linked in chains. Nonessential amino acids
can be synthesized in the body. The nine essential amino acids cannot be synthesized in the
body or be made in amounts sufficient to meet physiological need. Since all body cells contain
protein, routine maintenance and repair of body tissue requires a continual supply of amino
acids to synthesize proteins. Growth of new tissue requires additional protein.
The Functions of Body Proteins
The major role of dietary protein is to supply amino acids for the synthesis of proteins needed
in the body, although dietary protein can also serve as an energy source. Proteins act as
enzymes, as well as perform many other functions in the body. They help regulate water and
acid-base balance. Antibodies and some hormones are made of proteins. In the cell membrane,
protein “pumps” enable the cell to take up and retain specific compounds while excluding
others.
How the Body Handles Proteins
Food proteins are broken down into amino acids by the digestive system, and then reassembled
into needed proteins within the body cells. Protein digestion begins in the stomach and
continues in the small intestine, where the resulting amino acids are absorbed and then
released into the bloodstream. The body cells must have all the essential acids required in
order to make a specific protein. If any are missing, the process halts and the amino acid
strand is dismantled so that the amino acids can be utilized by other cells.
Protein Quality of Foods
A complete protein supplies all the essential amino acids; a high-quality protein not only
supplies them but also provides them in the appropriate proportions. Animal protein sources
are generally of higher quality than vegetable protein sources, but diets composed of plant
foods provide plenty of protein, as long as a variety of nutrient-dense and complementary
protein foods are chosen.
Recommended Protein Intakes
The AMDR for protein is 10%-35% of total caloric intake. The RDA for protein for the healthy
adult is 0.8 grams of protein per kilogram of desirable body weight.
Protein and Health
Kwashiorkor is a disease in which protein is lacking. It typically occurs in children after
weaning, with the severest symptoms observed after the age of 2. Protein deficiency also can
occur simply because calories are inadequate (marasmus). The deficiencies of protein and
calories, which often go hand in hand, are together called protein-energy malnutrition (PEM)
and are a worldwide malnutrition problem.
Misconceived notions abound regarding protein in the diet; the most obvious of these is that
more is better. However, the higher a person’s intake of animal protein sources such as meat,
the more likely it is that fruits, vegetables, and grains will be crowded out of the diet, making it
inadequate in other nutrients. Many health organizations now recommend a diet that
emphasizes vegetables, fruits, legumes, and whole grains in order to protect against cancer,
heart disease, stroke, diabetes, and obesity. Most Americans consume higher intakes of protein
than recommended.
In the USDA’s MyPlate, the foods that supply protein in abundance are found in the Dairy
Group and the Protein Group. The Vegetables Group and Grains Group also contribute some
protein.
The Vegetarian Diet
The chapter addresses the forms of vegetarianism and discusses the nutrient considerations
and benefits of planning plant-based menus.
Food Allergy—Nothing to Sneeze At
A food allergy is the response of the immune system to a food component that is recognized as
an allergen. This allergen provokes the release of IgE antibodies, which signal mast cells to
release chemicals (e.g., histamine) that produce the characteristic allergy symptoms. The
prevalence of food allergy is greatest in the first few years of life and is believed to be the result
of the child’s immature immune system. The immature digestive system may allow more intact
allergen proteins to enter the bloodstream. Early exposure to certain foods can also play a role
in development of food allergy in children.
Wonder Bean—The Benefits of Soy
Recent findings show that substances such as phytoestrogens and isoflavones, found in
soybeans, can lower cholesterol and help prevent disease. Numerous studies attest to the
role soy foods may play in reducing risk for certain forms of cancer, heart disease, and
osteoporosis, in controlling diabetes, and in easing a woman’s transition through
menopause.
Chapter 7 Summary
Turning Back the Clock
Though vitamin deficiency diseases were familiar to people in ancient times, they were not
connected with consumption of certain foods until the 16th century or later. Over time, people
identified which foods were lacking in the diets of people with deficiency diseases, and then
began to analyze food constituents in the mid-19th century. It was not until the 20th century,
however, that scientists were able to identify the particular substances—named vitamines—
that would prevent these diseases if consumed.
The Two Classifications of Vitamins
Vitamins fall into two categories: those that dissolve in water, or water soluble; and those that
dissolve in fat, or fat soluble. To date, scientists have identified 13 vitamins, each with its own
special roles to play. There are nine water-soluble vitamins: eight B vitamins and vitamin C.
Each of the major food groups supplies a number of vitamins. The body excretes water-soluble
vitamins if the blood levels rise too high. As a result, they rarely reach toxic levels in the body.
In contrast, the four fat-soluble vitamins—A, D, E, and K—are stored in the liver and in body
fat, making it possible for megadoses of the fat-soluble vitamins to build up to toxic levels in
the body.
Color Your Plate with Vitamin-Rich Foods—and Handle Them with Care
This chapter’s Savvy Diner feature looks at the importance of adding a variety of colorful fruits
and vegetables to the diet and discusses the effects of cooking and processing on a food’s
nutrient content. In storing and cooking vitamin-rich foods, the principles to remember are to
exclude air, chill, minimize vitamin losses in water, and avoid overcooking.
The Antioxidant Vitamins
Antioxidants fight oxygen or rather keep oxygen from inappropriately reacting with body parts
and reduce the risk of creating free radicals that can cause severe damage in the body. The
body uses its own defenses to along with nutrient antioxidants to protect itself from these
potentially damaging molecules. The antioxidant nutrients include vitamin C, vitamin E, and
the carotenoid beta-carotene.
Vitamin C acts as an antioxidant, helps to enhance the absorption of iron from plant foods,
and promotes the formation of the protein collagen. Deficiency of vitamin C causes scurvy. The
best food sources of vitamin C are citrus fruits, strawberries, cantaloupe, broccoli, and other
members of the cabbage family. The antioxidant vitamins (vitamin C, vitamin E, and the
carotenoids—including beta-carotene) and many phytochemicals found in plant foods serve the
body by protecting it from damaging compounds known as free radicals that can promote heart
disease and cancer, among other conditions.
The best-substantiated role of vitamin E in human beings is as an antioxidant that protects
vitamin A and the polyunsaturated fatty acids (PUFA) from destruction by oxygen. The human
requirement for vitamin E is known to vary with polyunsaturated fatty acid intake; since the
vitamin occurs with PUFA in foods, it is normally supplied in the needed amounts.
Vitamin A as a part of visual pigments is essential for vision. It is involved in maintaining the
integrity of mucous membranes throughout the internal linings of the body, and thus in
promoting resistance to infection. It helps maintain the skin and is essential for the remodeling
of bones during growth or mending. The recommended intake for vitamin A is easily met by
consuming the vitamin’s precursor form—beta-carotene—from food sources such as dark
green, leafy vegetables, carrots, cantaloupe, or broccoli.
Vitamins for Healthy Blood
Many vitamins and minerals serve blood-related functions in the body. These include vitamins
B12, B6, folate, and K. These vitamins help reduce the risk of several diseases, including neural
tube defects, heart disease, and anemia.
Folate is involved in pathways leading to the synthesis of new cells and plays a crucial role in a
healthy pregnancy.
Vitamin B12 works closely with folate, enabling it to make new red blood cells.
Vitamin B6 facilitates protein metabolism.
Vitamin B6 is most abundant in meats, vitamin B12 is found only in animal products, and folate
is supplied by green, leafy vegetables, legumes, and foods fortified with folic acid.
Vitamin K promotes normal blood clotting; deficiency causes hemorrhagic disease. The vitamin
is synthesized by intestinal bacteria and is available from foods such as leafy green vegetables
and milk.
Vitamins for Healthy Bones
Bones are made up of a complex matrix of living tissue into which minerals—principally
calcium and phosphorus—are deposited. Peak bone mineral mass is achieved around age
thirty and then bone mineral content begins to decrease. Besides calcium, several other
vitamins (and minerals) are needed for the growth and maintenance of a healthy skeleton.
These include, vitamins D, K, and A, and beta-carotene.
Vitamin D promotes intestinal absorption of calcium, mobilization of calcium from bone stores,
and retention of calcium by the kidneys, and it is therefore essential for the mineralization of
bones and teeth. Deficiency of vitamin D causes rickets in children and osteomalacia in adults.
The recommended adult intake is best met by consuming fortified products such as milk or
breakfast cereals.
Accumulating evidence supports a role for vitamin K in maintenance of bone health.
Vitamins and Energy Metabolism
Many vitamins are essential for energy metabolism. Metabolism involves the maintenance of a
supply of energy, or ATP, that is available for the various energy-requiring processes of the
body. The key vitamins include: thiamin, riboflavin, niacin, B6, folate, pantothenic acid, biotin,
and B12.
The B vitamins serve as coenzymes, assisting many enzymes in the body. Thiamin, riboflavin,
niacin, and pantothenic acid are especially important in the reactions that release energy from
carbohydrate and fats. Biotin is involved in a number of body processes, including energy
metabolism. Deficiency diseases involving the B vitamins include beriberi (thiamin), pellagra
(niacin), and anemia (folate or vitamin B12).
Thiamin is widely distributed in foods; a balanced and varied diet of nutritious foods will best
ensure an adequate intake. Riboflavin is concentrated in milk products and leafy green
vegetables. Niacin is found wherever protein is found and can also be made from the amino
acid tryptophan. Pantothenic acid and biotin are widespread in the food supply.
Vitamin-Like Compounds
The conditionally essential nutrient choline is needed for metabolism of homocysteine and
manufacture of lecithin and other compounds. Choline has a DRI; sources are many and
include milk, eggs, and peanuts. The so-called “nonvitamins” are required by other organisms
but not essential in the human diet. Examples of nonvitamins include inositol and carnitine.
Phytonutrients in Foods: The Phytochemical Superstars
Phytochemicals, nonnutritive substances in plants, are an exciting new area of research with
health-protective benefits. These chemicals give plants their bright coloring. These substances
found in various fruits and vegetables are thought to provide protection from certain diseases
including heart disease, some cancers, and cataracts, among others.
Choosing a Vitamin-Mineral Supplement
It is estimated that over half the U.S. population take vitamin and mineral supplements
regularly, a $20 billion business. However, certain populations may benefit from appropriate
supplementation when warranted. Most healthy people should be able to meet their nutritional
needs through a healthful diet.
Medicinal Herbs
Herbs used as medicines have been a part of human development throughout history.
Consumption of medicinal herbs is on the rapid rise in the U.S. This may be due to several
factors including “returning to nature,” cost, distrust in the medical system, or desire for
alternative medicine. However, care should be exercised when taking these substances, as they
are not regulated and can cause problems or toxicity if not used judiciously.
Nutrition and Cancer Prevention
Though research has been unable to consistently and clearly demonstrate links between a
particular diet and cancer, diet is considered one of the many lifestyle/behavioral factors that
affect cancer risk. Authorities recommend the following for cancer prevention: maintain a
healthy weight, avoid or limit energy-dense beverages and foods, consume produce rich in
beta-carotene and vitamin C as well as cruciferous vegetables and whole grains, limit red and
processed meat, salt, and sodium-processed food intakes, and meet recommended intakes for
calcium and fiber (but not with supplements). Other positive behaviors include exercising
regularly and avoiding alcohol and tobacco products.
Chapter 8 Summary
The Minerals
The discovery of the functions of minerals in the body is a relatively recent one. Minerals do not
contribute energy to the body but work in diverse ways to facilitate chemical reactions and
other body processes.
The Two Classifications of Minerals
The minerals are divided into two categories, major and trace minerals. The division is based
on the amounts in the body and what is needed in the diet. Both play vital roles within the
body and can be toxic is high amounts.
Minerals for Healthy Bones
Bones are made up of a complex matrix of living tissue into which minerals—principally
calcium and phosphorus—are deposited. Peak bone mineral mass is achieved around age
thirty and then bone mineral content begins to decrease. Besides calcium, several other
vitamins and minerals are needed for the growth and maintenance of a healthy skeleton. These
include, vitamins D, K, and A, beta-carotene, and the minerals calcium, phosphorus,
magnesium, and fluoride.
Calcium, the most abundant body mineral, is found mostly in the bones (99%), where it
provides structural support and a calcium bank that can be drawn from as necessary to
maintain body fluid levels. The 1% of calcium in fluids is necessary for nerve transmission,
muscle contractions, and cell membrane integrity, and is also an enzyme cofactor. Dietary
sources include dairy products, green vegetables, and fortified foods such as juice.
Phosphorus, the next most abundant mineral, is found mostly (85%) within bones as calcium
phosphate, but also as part of DNA, RNA, and phospholipids. Phosphorus also serves to
activate many B vitamin-based enzymes. It is present in almost all foods; good sources include
animal foods and carbonated beverages.
Magnesium, important in muscle relaxation, tooth enamel integrity, and metabolism, is found
in nuts, legumes, grains, dark-green vegetables, seafood, chocolate, and cocoa.
Fluoride improves the crystalline structures of bones and teeth so they are more resistant to
bone loss and decay, respectively. The usual source is fluoridated water.
Minerals for Healthy Blood
Many vitamins and minerals serve blood-related functions in the body. Besides several
vitamins, the minerals iron, zinc, and copper are particularly important to blood functioning
and oxygen carrying.
Iron, as part of hemoglobin within red blood cells, is responsible for oxygen transport within
the circulatory system. A deficiency results in anemia—a reduction in the number and size of
blood cells—accompanied by weakness, fatigue, and pallor. The nonheme form of iron is less
absorbable than the heme form (found in animal flesh); nonheme iron absorption can be
increased by vitamin C or decreased by binders (phytates, oxalates, and tannins). Iron toxicity
(known as iron overload when caused by the body’s over-absorption of iron) is dangerous.
Zinc participates in the regulation of cell division and growth, energy metabolism, and free
radical disposal, and in taste perception, wound healing, and sexual maturation, among other
roles. Dietary sources include high-protein animal foods and whole grains.
Copper plays many roles, and is involved in red blood cell and collagen production, wound
healing, and nerve sheath maintenance. Whole grains, nuts, seeds, legumes, and shellfish
provide copper.
Minerals and Energy Metabolism
Many minerals are essential for energy metabolism. Metabolism involves the maintenance of a
supply of energy, or ATP, that is available for the various energy requiring processes of the
body. The key minerals include: iron, zinc, iodine, chromium, and sulfur.
Chromium, found in many whole foods, is needed for carbohydrate and lipid metabolism and
enhances insulin’s effects. Sulfur is incorporated into many dietary and body proteins, where it
helps them hold their shapes.
Iodine is required for the thyroid hormones that regulate basal metabolism. A deficiency or
excess causes enlargement of the thyroid gland—goiter. Deficiency during pregnancy can result
in an infant born with cretinism, marked by severe mental and physical retardation. Since
iodine in foods varies based on soil content where the food originates, iodized salt is still
considered an important source in the U.S.
Selenium, an antioxidant and another constituent of thyroid hormones, is provided by whole
grains, meat, seafood, and produce grown in selenium-containing soil.
Water, Minerals, and Fluid Balance
Water is by far the nutrient most needed by the human body. It is a part of every cell, tissue
and organ and accounts for 60 percent of body weight. Water performs many tasks vital to life.
Many important minerals are involved in helping to maintain the balance of water (fluids)
within the appropriate places within the body. These include sodium, chloride, potassium (the
electrolytes), and phosphorus.
Sodium, Potassium, and Chloride
Sodium, potassium, and chloride all function as electrolytes, but serve other roles in the body
as well. Sodium is infamous for its connection with hypertension, so the Dietary Guidelines
recommend limiting its intake while increasing intake of potassium, which is associated with
lower blood pressure. Potassium is critical for maintaining a steady heartbeat; chloride, found
with potassium inside cells, is part of the hydrochloric acid that provides acidity to stomach
juice and aids protein digestion.
Choose and Prepare Foods with Less Salt
The Savvy Diner feature provides tips for reducing dietary sodium by making wise choices
when grocery shopping, cooking, and dining at restaurants. For example, limiting intakes of
processed foods, salty snacks, and condiments and using herbs in preference to salt as a
seasoning are suggested.
Diet and Blood Pressure—Beyond Just The Salt Shaker
The Nutrition Action feature discusses the causes, treatment, and prevention of hypertension.
If you would like to reduce your risk of developing high blood pressure, you can do so by:
•
•
•
•
•
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Adopting an eating pattern rich in fruits, vegetables, legumes, and low-fat dairy products—
similar to the DASH diet;
Maintaining a healthy weight;
Keeping sodium intake at or below recommended levels;
Pursuing an active daily lifestyle;
Drinking in moderation, if at all;
Not smoking.
Osteoporosis—The Silent Stalker of the Bones
The chapter’s Spotlight provides an overview of osteoporosis risk factors, diagnosis, prevention,
and treatments. To build bone mass and lower risk for osteoporosis:
•
•
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Maximize peak bone mass; consume the recommended amount of calcium (and vitamin D)
for your age.
Consume alcohol only in moderation, if at all, and avoid cigarettes all together.
Exercise regularly, since exercise can reduce the risk of developing osteoporosis by making
bones stronger and increasing their ability to absorb calcium.
Chapter 9 Summary
Water
Adults consume 1 ½ to 3 quarts of water daily. Most comes from sources other than “straight”
water, including the foods people eat. People consume a variety of water sources including
juice, milk, soft drinks, and tap and various forms of bottled water.
Juices
Juices have become a major source of beverages for many people. Juices come in many
varieties and offer both benefits, such as antioxidants and phytochemicals, and possible
drawbacks like added calories and loss of other nutrients found in fresh fruit.
Milk
Cow’s milk is a nutrient-dense beverage, especially when it has the fat removed and is fortified
with vitamins A and D.
Caffeinated Beverages: Coffee, Tea, Cocoa, and Soft Drinks
Caffeine is consumed in the form of many beverages, with the most provided by coffee,
although other sources do/can provide significant amounts. The health/disease effects of
caffeine are still being investigated. Although the final answer is not in, a small amount of
caffeine does not seem problematic for most people and may confer some benefits. Most
recommendations list no more than 150 milligrams a day as an acceptable level.
Coffee. Popular worldwide, coffee consumption is associated with reduced type 2 diabetes risk.
The mechanism is unknown, but is not believed to be caffeine. Coffee antioxidants also have
anti-inflammatory properties that are protective at a dose of 1-3 cups of coffee per day.
Tea. Tea leaves are processed by steaming and drying (green tea), fermentation (black tea), or
wintering and partial fermentation (oolong tea). The phytochemicals, antioxidants, and caffeine
in tea have been linked with reduced risks of many chronic conditions, including heart disease,
cancer, and neurodegenerative disease. The more tea consumed, the greater these effects
become.
Cocoa. Cocoa provides minerals, fat, protein, antioxidants, phytochemicals, and caffeine. Dark
chocolate consumption may reduce cardiovascular risk.
Soft Drinks. Soft drinks are a major contributor to empty calorie intake in the U.S., providing
>1/3 of the refined sugars in the diet (much as high-fructose corn syrup). Research links soft
drink consumption with increased energy intakes, weight gain, poor overall nutrition, and
increased chronic disease risk.
Functional Beverages
Energy Drinks. Energy drinks are non-alcoholic drinks promising a host of possible energyenhancing effects. Most contain a variety of ingredients, all of which may not be safe, especially
in combination. The primary ingredients, as in soft drinks, are sugar and caffeine.
Sports Drinks. “Sport drinks” first appeared in 1965 and were developed by a researcher at
the University of Florida as a fluid and electrolyte replenishment beverage for football players.
Since then, other products have pushed this to a $2.6 billion yearly business. These drinks
may enhance athletic performance by delaying fatigue and aiding postexercise recovery.
Athletes should select a sports drink with 6% carbohydrate as glucose, sucrose, and fructose
(but not all fructose); sodium; and no carbonation or caffeine.
“Enhanced” Waters. Various substances like vitamins, caffeine, antioxidants, fiber, and
various sugars have been added to water to purportedly enhance the effect that “plain” water
has. These “enhanced” waters are generally no more healthful than other sugar-sweetened
beverages.
Alcohol
Alcohol is a general term used to describe a group of organic chemicals with common
properties. The most commonly ingested form of alcohol is ethyl alcohol or ethanol (EtOH),
providing 7 calories/gram. Alcohol is a sedative and central nervous system (CNS) depressant.
Impairment after alcohol consumption is directly correlated to the amount of alcohol in the
blood. As a college student, you can make the choice to drink responsibly by “knowing when to
say when” if you drink. You can reduce your risk of alcohol-related problems by using common
sense and avoiding alcohol in dangerous situations.
Absorption and Metabolism of Alcohol. About 20% of alcohol is absorbed in the stomach,
and the remaining 80% is absorbed through the small intestine. Alcohol absorbed through the
small intestine passes into the portal vein, where it is transported to the liver. Alcohol is
metabolized more slowly than it is absorbed. It takes approximately 1 hour to metabolize a
standard drink. Rate of alcohol metabolism depends, in part, on the amount of alcohol
dehydrogenase formed and varies among individuals.
Factors Influencing Absorption and Metabolism. Presence of food in the stomach slows
absorption of alcohol. Women metabolize alcohol differently than men, which sends 30% or
more alcohol into their bloodstream than men of the same weight from the same amount of
alcohol.
Effects of Alcohol. Even small concentrations of alcohol can affect the central nervous system
and slow reactions. The body responds to alcohol in stages, and a person can build up
metabolic and functional tolerances to alcohol. Once a person’s body has adapted to alcohol
intake by developing tolerances, more and more alcohol must be consumed to achieve the
desired effect, often leading to addiction.
Impact of Alcohol on Nutrition. Light drinkers in good health and otherwise well nourished
often suffer nothing more than weight gain from the excess calories alcohol provides. Alcohol
can negatively affect nutritional status, depending on the amount of alcohol consumed and a
person’s nutritional or health status. Nutritional deficiencies can develop in drinkers who
substitute alcohol for food.
Health Benefits of Alcohol. Health benefits or risks depend on amount of alcohol consumed
and age of the drinker. Deaths reduced by moderate alcohol consumption are generally in age
groups with high rates of coronary heart disease—in other words, in age groups 45 years and
older.
Health Risks of Alcohol. Most deaths due to alcohol consumption occur in people younger
than 45 years. Alcohol can be dangerous when taken in combination with other drugs
(prescription or over-the-counter) or when someone gets behind the wheel of a car, even if it’s
after just a “few” drinks. Dependency on alcohol can develop, especially if a blood relative has
problems with alcohol abuse. As with other drugs, there is a beneficial dose of alcohol and a
dose that will cause harm. Among young adults, risks (alcohol abuse and dependence, alcoholrelated violent behavior and injuries) of alcohol consumption outweigh any benefits that may
accrue later in life.
Other Risks. Excessive alcohol use may result in night blindness, increased risk for breast and
other cancers, liver damage, hypertension, increased stroke risk, pancreatitis, gastrointestinal
symptoms, brain damage, decreased production of sex hormones, anemia, and emotional and
social problems.
Weighing the Pros and Cons of Alcohol Consumption. One way is to investigate the common
causes of morbidity and mortality for individuals of your age and gender, determine how likely
it is that moderate alcohol use will reduce risks, and compare this to the likelihood that use
will pose risks of its own.
What Is Alcohol Abuse or Alcoholism? Alcoholism is a dependency on alcohol involving
psychological and physical cravings for the drug and loss of ability to control drinking. NA and
AA use a scale to grade alcohol addiction. Use refers to drinking without negative
consequences, misuse to drinking which results in negative consequences, abuse to continued
drinking in spite of negative results, and addiction to compulsive drinking.
Fetal Alcohol Syndrome
The Spotlight at the end of the chapter discusses problems that occur when women drink while
pregnant. Fetal alcohol syndrome is just one example of how alcohol affects health
consequences of others in addition to the drinker.
Chapter 10 Summary
The escalating epidemic of obesity results in thousands of preventable deaths each year. Many
factors, including genetics, influence body weight, but excess energy intake and physical
inactivity are the leading causes of overweight and obesity. Both underweight and overweight
increase the risk of incurring various illnesses as well as various social and psychological
stigmas.
A Closer Look at Obesity
The WHO considers obesity an epidemic with many contributing factors: genetics, large portion
sizes, availability of energy-dense foods, sedentary lifestyles, and a built environment that fails
to facilitate fitness.
Problems Associated with Weight
Underweight renders a person more vulnerable to physical stressors. Overweight increases
risks of hypertension, heart disease, and diabetes in those who are genetically predisposed,
and has also been associated with gallbladder disease and breast cancer.
What Is a Healthy Weight?
To determine health risks associated with overweight and obesity, health professionals use
three factors: body mass index, waist circumference, and current health status. The latter may
include heart disease, type 2 diabetes, high blood cholesterol, high blood pressure, cigarette
smoking, osteoarthritis, gallstones, or sleep apnea. An initial goal for treatment of overweight
and obese people with risk factors is to reduce body weight by about 10% at a rate of about 1
to 2 pounds per week. An overweight person who wants to lose weight needs to understand the
concept of total energy needs as well as successful weight-loss strategies.
Energy Balance
Unhealthy weight results from an unbalanced energy budget (food energy in vs. energy
expended on basal metabolism and activity). While the majority of energy used by the body
fuels basal metabolism—accounting for 60%—the person’s physical activity level is important
as well, and can help determine whether that person will have a healthy or unhealthy weight.
Causes of Obesity
In general, two schools of thought address the problem of obesity’s causes. One attributes it to
inside-the-body causes (genetics: set-point theory, hormones, fat-cell theory); the other, to
environmental factors (external cue theory). Eating behavior may be a response not only to
hunger or appetite but also to complex human sensations such as yearning, craving, or
compulsion. No doubt, the causes of obesity are complex and many causes may contribute to
the problem in a single person. Given this complexity, it is obvious that there is no panacea for
successful weight maintenance. The top priority should be prevention, but where prevention
has failed, the treatment of obesity must involve a three-pronged approach, including adopting
healthful eating habits, moderate levels of exercise, and behavior change.
Weight Gain and Loss
Weight change may be related to any of the body’s components, including fat and lean tissues,
water, and bone minerals. Excess energy is stored within the body as limited quantities of
glycogen and virtually unlimited quantities of fat. During a fast, glycogen is soon exhausted,
and then the body metabolizes fat plus muscle tissue, because the nervous system cannot use
fat for fuel. If the fast continues, the body adapts by manufacturing ketone bodies, which the
brain can use when glucose is unavailable.
Medications to assist obese persons with weight loss include, among others, Adipex-P/ Fastin,
which induces satiety and increases calorie expenditure, and Xenical (OTC form: alli), which
reduces the body’s absorption of fat. Treatments for severe obesity include surgery to reduce
stomach volume and nutrient absorption from the small intestine.
Successful Weight-Loss Strategies
The problem with going on a rigid diet with a goal of, say, a 15-pound weight loss in 3 weeks is
that it’s a quick fix—the dieter attempts to gain a temporary solution to what is typically a
chronic problem. People are attracted to fad diets because of the dramatic weight loss that
occurs within the first few days. Such people would be disillusioned if they realized that the
major part of this weight loss is a loss of body protein, along with quantities of water and
important minerals. A more healthful alternative is to develop habits gradually that you can
live with permanently and that will help you shed pounds and keep them off over the long run.
Instead of measuring your success by the needle on the scale, gauge your progress by the
strides you make in adopting good eating and exercise habits as well as healthful attitudes
about yourself and your body. Criteria for success are permanent changes in eating and
exercise habits and maintenance of the goal weight over time. To succeed, you should
personalize your weight-loss plan, aim for gradual weight loss, and adopt a physically active
lifestyle.
Weight-Gain Strategies
Healthful weight gain consists of building up muscle mass through weight training and
increased calorie intake.
Breaking Old Habits
Behavior modification strategies can assist with weight loss and maintenance by helping you
make needed lifestyle changes. When you are ready to change, you can follow the steps of the
behavior modification process to set personal goals, make a commitment to change, develop
and implement a plan for change, and periodically evaluate progress toward the goals.
The Eating Disorders
The term eating disorder involves a wide spectrum of conditions, including anorexia nervosa,
bulimia nervosa, and binge-eating disorder. Although the various conditions differ in their
origin and consequences, they appear to have similarities among them—all of the conditions
exhibit an excessive preoccupation with body weight, a fear of body fatness, and a distorted
body image. Some researchers suspect that a complex interplay among environmental, social,
and perhaps genetic factors triggers the development of eating disorders, mostly in women.
Chapter 11
Chapter Summary
Getting Started on Lifetime Fitness
The benefits of regular exercise make up an impressive list. Exercise is one of the most effective
strategies against multiple chronic health disorders. Despite evidence of the benefits, the
majority of Americans are not meeting the recommended guidelines for physical activity.
The Components of Fitness
Improving fitness involves learning about and employing concepts relating to overload, the usedisuse principle, and aerobic and anaerobic exercise. Exercise frequency, intensity, and
duration can be increased to improve fitness. Fitness requires a reasonable weight for a
person’s height and enough of each of the measurable components of fitness—flexibility,
muscle strength, muscle endurance, and cardiovascular endurance—to meet life’s demands.
For total fitness, an exercise program that incorporates strength training, stretching, and
cardiovascular endurance activity is best. Cardiovascular endurance helps maintain a healthy
heart and circulatory system and exercises that promote cardiovascular endurance are the best
for making short-term fitness gains and long-term health improvements. Strength training also
helps with weight loss by increasing lean muscle mass and thus increasing a person’s basal
metabolic rate.
Energy for Physical Activity
Both aerobic and anaerobic energy systems support physical activity by providing energy for
muscle cells. The oxygen required for aerobic energy systems is more amply supplied by a wellconditioned cardiovascular system. Cardiovascular fitness is achieved through regular aerobic
activity that increases the heart rate to within the target range for at least 20 minutes each
session.
Fuels for Physical Activity
Your energy-producing pathways require the muscle fuels: glucose and fatty acids. Your
muscles, and to some extent your liver, supply carbohydrate to your muscles from their
carbohydrate (glycogen) supplies. The fatty acids come mostly from fat inside the muscles but
partly from fat that is released from the body’s fat stores, and the blood delivers these fatty
acids to the muscles.
A diet rich in complex carbohydrate and low in fat not only provides the best balance of
nutrients for health but also supports physical activity best. Training can increase the amount
of glycogen a muscle can conserve during exercise. Likewise, exercise training improves the
body’s ability to deliver fat to working muscles, and trained muscles have an increased ability
to use the fat for energy when oxygen is present—sparing the valuable glycogen. Finally, how
well your muscles metabolize fuels for energy depends on your supply of vitamins and
minerals.
Protein Needs for Fitness
The body of an athlete may use slightly more protein, especially during the initial stages of
training. However, muscles grow in response to hormonal signals and the demands of work,
not increases in dietary protein.
Food for Fitness
Knowledge of what fuels muscles use may lead the athletic competitor to consume a diet
especially high in complex carbohydrates just before an event. The best choices for the meal
before a competitive event are foods that are high in carbohydrate and low in fat, protein, and
fiber.
Fluids and Physical Activity
Sufficient fluid intake is critical to the prevention of heat stroke and to the health and
performance of anyone who exercises. Replenishing fluid lost during exercise is easily
accomplished by drinking fluid before, during, and after exercise.
Vitamins and Minerals for Physical Activity
B vitamins to facilitate energy release and antioxidants to curtail the oxidation resulting from
increased oxygen use during exercise are both important vitamin classes for athletes. Iron,
which is needed to deliver oxygen to working muscles, is an especially important mineral for
athletes. Calcium is important for maintaining bone density.
Athletes and Supplements—Help or Hype?
Myths abound concerning fitness and nutrition. However, the scientific evidence to support
most of the claims that special ergogenic aids will make an athlete run farther or jump higher
is lacking. With common sense and an awareness of fitness components and concepts, people
can learn to exercise safely and enjoy its many benefits.
Chapter 12 Summary
Pregnancy: Nutrition for the Future
Growth is a major factor influencing the nutritional needs of developing infants and children.
The growth rate is faster during prenatal life and the first year. During pregnancy, changes in
both mothers’ and infants’ bodies necessitate increased intakes of the growth nutrients. A
pregnant woman who begins at a healthy weight should gain about 25 to 35 pounds from foods
of high nutrient density. Normal weight gain and adequate nutrition support the health of the
mother and the development of the fetus. Low weight gain in pregnancy is associated with
increased risk of delivering a low-birth-weight baby. Alcohol, smoking, drugs, herbal remedies,
dieting, and unbalanced nutrient intakes should be avoided during pregnancy.
Healthy Infants
Breast milk or formula provides the rapidly growing infant with needed nutrients in quantities
suitable to support the infant’s growth. The advantages of breast milk over formula are that it
protects the infant against disease and allergy development and is premixed to the correct
proportions. Additions to a baby’s diet are selected according to the baby’s changing nutrient
needs and readiness to handle new foods. Among the first nutrients needed in amounts beyond
those provided by breast milk are iron and vitamin C. Feeding a balanced diet, avoiding emptycalorie foods, and encouraging infants to learn to like a variety of foods can promote normal
weight gain, tooth development, and health.
Early and Middle Childhood
After the age of one, a child’s growth rate slows, and with it, the appetite. However, all essential
nutrients continue to be needed in adequate amounts from foods with a high nutrient density.
When children go to school, their nutrition needs are partly met by school lunch programs.
Another influential factor in the lives of children is television, with many advertisements for
sugary foods; others include vending machines and fast foods, which often limit choices to
foods of low quality.
Sound nutrition practices may prevent future health problems to some extent—among these
problems are obesity, iron-deficiency anemia, cardiovascular disease, and diabetes. In recent
years, the percentage of children who are overweight has more than tripled. Genetic
susceptibility to obesity, lifestyle, family eating patterns, large portion sizes, lack of positive role
models, and inactivity all contribute to overweight and obesity in this population.
The Importance of Teen Nutrition
The teen years mark the transition from a time when children eat what they are fed to a time
when they choose for themselves what to eat. Specific nutrition-related problems among U.S.
adolescents include undernutrition, overweight, iron-deficiency anemia, low dietary calcium
intakes, high blood cholesterol levels, dental caries, and eating disorders.
Nutrition in Later Life
Aging is an inevitable, natural process programmed into our genes at conception. Many of the
changes are inevitable, but a healthful lifestyle that combines regular physical activity with
adequate intakes of all essential nutrients can forestall degeneration and improve the quality of
life into the later years.
Although caloric needs may decrease with age, the need for certain nutrients such as calcium,
vitamin D, vitamin C, vitamin B12, and vitamin B6 may actually increase with the effects of
aging. A narrower food pyramid for adults over age 70 shows a recommended eating pattern
that reflects the lower caloric needs of most healthy older adults and emphasizes the need for
adequate fluid intake. The enjoyment of food is enhanced if loneliness—a major problem of
older people living alone—can be alleviated. Eating with others often restores the appetite and
health that may seem to be failing due to degenerative disease.
As a person gets older, the chances of suffering a chronic illness or disability become greater.
Individually or in combination, the social, economic, psychological, cultural, and
environmental factors associated with aging may interact with the physiological changes and
further affect nutrition status in older adults. Old age need not be a time of despair, isolation,
and ill health. Preparation for enjoyable later years should include financial planning, the
establishment of lasting social contacts, the learning of skills and activities that can be
pursued into later life, the maintenance of a program of regular physical activity, and the
cultivation of healthy nutrition status throughout life.
Looking Ahead and Aging Wisely
Adults should prepare financially, socially, and health-wise for the future, so that they can
reach old age with a healthy mind and body. Avoiding social isolation is especially important.
Addressing Weight Problems in Children and Adolescents
A growing population of overweight children in the U.S. is developing chronic diseases such as
type 2 diabetes, CVD, and gallbladder disease. Social trends, including fast-food dining and
sedentary activities for children, have contributed to overweight in children. Modeling for and
teaching healthy eating and exercise habits to children can help them to grow without
excessive weight gain, and maintain a healthy body composition later in life.
Chapter 13 Summary
Foodborne Illnesses and the Agents That Cause Them
The Food and Drug Administration’s (FDA’s) top item of concern with regards to the food
supply is foodborne illness, because it is a frequent threat to people who consume food that
has been contaminated by toxic microorganisms during production, processing, packaging,
transport, storage, or preparation. Common microbes responsible for foodborne illness include
Campylobacter jejuni, Salmonella, and Staphylococcus aureus; some of the more deadly but less
common include Clostridium botulinum and Escherichia coli O157:H7. Herbs sold in
supplemental form as well as some common foods may contain natural toxicants. Food
poisoning can be fatal, and consumers must learn to avoid common food safety mistakes.
Safe Food Storage and Preparation
Consumers should keep cold foods cold, wash hands and surfaces often, keep hot foods hot,
and prevent cross-contamination. More specificially, safe food preparation tips include using
proper temperatures for storage, not allowing cooked food to come in contact with raw foods or
with the same surfaces on which it was prepared raw, cooking at high enough temperatures to
kill organisms, and using hot, soapy water for cleaning utensils, among others.
Pesticides and Other Chemical Contaminants
Chemical contaminants are increasingly present in the environment. Unlike pesticides, they
are not regulated, but find their way into foods by accident. Among the most serious
contamination problems of recent years have been those involving heavy metals such as lead
and mercury. Pesticides are poisonous substances, but are used intentionally to protect foods
against insects or other harmful pests. The Environmental Protection Agency (EPA), FDA, and
other agencies are charged with establishing residue tolerances for pesticides and monitoring
their presence in foods.
Food Additives
From a safety standpoint, food additives rank among the least hazardous substances in food.
Intentional food additives enhance the color, flavor, texture, or stability of foods or even
improve the nutritional value of certain items. The FDA requires that additives be safe and
imposes a specific set of testing procedures on manufacturers. Many food additives appear on
the GRAS (generally recognized as safe) list that is reviewed periodically as new facts or
concerns arise. Major classes of food additives include the artificial colors, artificial flavors and
flavor enhancers, artificial sweeteners, antimicrobial agents, antioxidants, and nutrient
additives. The FDA also regulates incidental additives in foods. These substances find their way
into food by accident as the result of some phase of production, processing, or storage.
Should You Buy Organically Grown Produce or Meats?
In order to minimize exposure to pesticides, some consumers opt for organically grown foods,
which are now regulated by the United States Department of Agriculture (USDA). The USDA
has created a national reference standard to define what is and what is not organic. Organic
crops must be raised without genetically modified seeds, pesticides, petroleum-based fertilizers,
or sewage sludge-based fertilizers; organically raised animals receive organic feed, access to the
outdoors, and no antibiotics or growth hormones.
New Technologies on the Horizon
Public health organizations striving to feed a fast-growing world population while ensuring a
safe food supply debate the benefits and risks associated with new ways of doing so. New food
technologies under consideration as alternatives to help improve the safety of our food supply
and to maintain the nutritional value of the foods available in the marketplace include
irradiation and genetic engineering. Irradiation involves exposing food to low doses of radiation,
which destroys insects and several types of bacteria. With genetic engineering, scientists can
alter a plant’s genes in an effort to make a particular trait more desirable. Despite many
concerns, some scientists are hopeful that careful use of genetic engineering will confer longterm benefits, such as the development of insect- and disease-resistant plants that allow
farmers to grow crops with fewer chemicals.
Spotlight: Global Food Insecurity
The phenomenon of hunger is today being discussed in terms of food security. Food insecurity
was once viewed as a problem of overpopulation and inadequate food production, but now
many people recognize it as a problem of poverty. Poverty is much more than an economic
condition and exists for many reasons, including overpopulation, greed, unemployment, and
the lack of productive resources such as land, tools, and credit. The chapter concludes that the
practical suggestions offered throughout the book for attaining the ideals of personal nutrition
are the very suggestions that support the health of the whole earth.