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Chapter 8
NUTRITION
Nutritional Requirements:
Components of a Healthy Diet
 Essential nutrients = substances the body must get
from food because it cannot manufacture them at all
or fast enough to meet its needs
 Proteins
 Carbohydrates
 Fats
 Vitamins
 Minerals
 Water
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Energy from Food
 Three classes of essential nutrients supply
energy. Which ones?
 Kilocalorie = a measure of energy content in
food; the amount of heat it takes to raise the
temperature of 1 liter of water 1°C; commonly
referred to as “calorie”
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Sources of Energy in the Diet
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Proteins—The Basis of Body
Structure
 Protein = a compound made of amino acids that
contains carbon, hydrogen, oxygen, and
nitrogen
 Of twenty common amino acids in foods, nine
are essential
 Proteins form key parts of the body’s main
structural components—muscles and bones—
and of blood, enzymes, cell membranes, and
some hormones
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Fats—Essential in Small
Amounts
 Fats supply energy, insulate the body,
support and cushion organs, absorb fatsoluble vitamins, add flavor and texture to
foods
 Essential fats are key regulators of body
process such as the maintenance of blood
pressure and the progress of a healthy
pregnancy
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Types and Sources of Fats
 Saturated fat = a fat with no carbon-carbon double
bonds; usually solid at room temperature
 Found primarily in animal foods and palm and coconut
oils
 Monounsaturated fat = a fat with one carbon-carbon
double bond; usually liquid at room temperature
 Found in certain vegetables, nuts, and vegetable oils
 Polyunsaturated fat = a fat with two or more carboncarbon double bonds; usually liquid at room temperature
 Found in certain vegetables, nuts, and vegetable oils
and in fatty fish
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Fats and Health
 Fats also affect triglyceride levels,
inflammation, heart rhythm, blood pressure,
and cancer risk
 Best choices = monounsaturated fats and
polyunsaturated omega-3 fats
 Limit intake of saturated and trans fats
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Fats and Health
 Fats affect blood cholesterol levels
 Low-density lipoprotein (LDL) = “bad”
cholesterol
 High-density lipoprotein (HDL) = “good”
cholesterol
 Saturated and trans fats raise levels of LDL;
trans fats also lower levels of HDL
 Unsaturated fats lower levels of LDL
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Carbohydrates—An Ideal
Source of Energy
 The primary function of dietary carbohydrate is to
supply energy to body cells.
 Some cells, such as those in the brain, nervous
system, and blood, use only carbohydrates for fuel
 During high-intensity exercise, muscles get most of
their energy from carbohydrates
 During digestion, carbohydrates are broken into
single sugar molecules such as glucose for
absorption; the liver and muscles take up glucose
and store it in the form of glycogen
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Simple and Complex
Carbohydrates
 Simple carbohydrates contain one or two sugar
units in each molecule
 Found naturally in fruits and milk and added to many other
foods
 Include sucrose, fructose, maltose, and lactose
 Complex carbohydrates consist of chains of many
sugar molecules
 Found in plants, especially grains, legumes, and tubers
 Include starches and most types of dietary fiber
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Whole Grains
 Before they are processed, all
grains are whole grains consisting
of an inner layer of germ, a middle
layer called the endosperm, and an
outer layer of bran
 During processing, the germ and
bran are often removed, leaving
just the starchy endosperm
 Refined carbohydrates usually
retain all the calories of a whole
grain but lose many of the nutrients
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Refined Carbohydrates Versus
Whole Grains
 Whole grains are higher than refined carbohydrates
in fiber, vitamins, minerals, and other beneficial
compounds
 Whole grains take longer to digest
 Make people feel full sooner
 Cause a slower rise in glucose levels
 Choose foods that have a whole grain as the first
item on the ingredient list on the food label
 Whole wheat, whole rye, whole oats, oatmeal, whole-
grain corn, brown rice, popcorn, barley, etc.
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Reading a Food Label
1. Serving Size
 The first place to start when you look at the Nutrition Facts label
 Serving sizes are standardized to make it easier to compare
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similar foods;
They are provided in familiar units, such as cups or pieces,
followed by the metric amount, e.g., the number of grams.
The size of the serving on the food package influences the
number of calories and all the nutrient amounts listed on the top
part of the label.
Pay attention to the serving size, especially how many
servings there are in the food package. Then ask yourself,
"How many servings am I consuming"? (e.g., 1/2 serving, 1
serving, or more)
In the sample label, one serving of macaroni and cheese equals
one cup. If you ate the whole package, you would eat two cups.
That doubles the calories and other nutrient numbers, including
the %Daily Values as shown in the sample label.
2. Calories (and calories from fat)
 Calories provide a measure of energy
 The calorie section of the label can help you
manage your weight.
 Only about 30% of your calories should come
from fat.
 Remember: the number of servings you
consume determines the number of calories
you actually eat (your portion amount).
 A guide: 40 Calories is low, 100 Calories is
moderate and 400 Calories or more is high
3. The nutrients
Limit These Nutrients
Eating too much fat,
saturated fat, trans fat,
cholesterol, or sodium may
increase your risk of certain
chronic diseases, like heart
disease, some cancers, or
high blood pressure.
Get Enough of These
Eating enough of
these nutrients can
improve your health
and help reduce the
risk of some diseases
and conditions.
Remember: You can use the Nutrition Facts label not only to help limit those
nutrients you want to cut back on but also to increase those nutrients you need
to consume in greater amounts.
5. Understanding the Footnote on the
Bottom of the Nutrition Facts Label
This statement must be on all food labels.
6. The Percent Daily Value (%DV)
5%DV or less is low and
20%DV or more is high
Plain vs Fruit Yogurt
Glycemic Index
 Consumption of carbohydrates causes insulin and
glucose levels in the blood to rise and fall
 Glycemic index = a measure of how the ingestion of
a particular food affects blood glucose levels
 Foods with a high glycemic index cause quick and
dramatic changes in glucose levels
 Diets rich in high glycemic index foods are linked to
increased risk of diabetes and heart disease
 High glycemic: Bread, Pasta, Rice, Baked goods
 Low glycemic: Fruits, Vegetables, Whole grains
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Acceptable Macronutrient
Distribution Ranges: Summary
 Protein = 10–35% of total daily calories
 Fat = 20–35% of total daily calories
 Carbohydrate = 45–65% of total daily
calories
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Fiber—A Closer Look
 Dietary fiber = nondigestible carbohydrates and
lignin that are present naturally in plants
 Functional fiber = nondigestible carbohydrates
isolated from natural sources or synthesized in a
lab and added to a food or supplement
 Total fiber = dietary fiber + functional fiber
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Types of Fiber
 Soluble (viscous) fiber = fiber that dissolves in water
or is broken down by bacteria in the large intestine
 Slows the body’s absorption of glucose
 Binds cholesterol-containing compounds
 Insoluble fiber = fiber that doesn’t dissolve in water
 Makes feces bulkier and softer
 Helps prevent constipation, hemorrhoids, and diverticulitis
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Sources of Fiber
 All plant foods contain fiber, but processing can
remove it
 Good sources of fiber:
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Fruits (especially whole, unpeeled fruits)
Vegetables
Legumes
Oats (especially oat bran)
Whole grains and wheat bran
Psyllium (found in some cereals and laxatives)
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Vitamins—Organic
Micronutrients
 Vitamins = organic (carbon-containing) substances
needed in small amounts to help promote and
regulate chemical reactions and processes in body
cells.
 Four vitamins are fat-soluble (A, D, E, and K)
 Nine vitamins are water-soluble (C and the eight Bcomplex vitamins: thiamin, riboflavin, niacin, vitamin
B-6, folate, vitamin B-12, biotin, and pantothenic
acid)
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Vitamins
 Vitamins are abundant in fruits, vegetables, and grains;
they are also added to some processed foods
 If you consume too much or too little of a particular
vitamin, characteristic symptoms of excess or deficiency
can develop
 Vitamins commonly lacking in the American diet:
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Vitamin A
Vitamin C
Vitamin B-6
Vitamin E
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Minerals—Inorganic
Micronutrients
 Minerals = inorganic (non-carbon-containing)
compounds needed in small amounts for regulation,
growth, and maintenance of body tissues and
functions
 There are about 17 essential minerals:
 Major minerals (those that the body needs in amounts
exceeding 100 mg per day) include calcium, phosphorus,
magnesium, sodium, potassium, and chloride
 Essential trace minerals include copper, fluoride, iodide, iron,
selenium, and zinc
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Minerals
 If you consume too much or too little of a particular
mineral, characteristic symptoms of excess or
deficiency can develop
 Minerals commonly lacking in the American diet:
 Iron = low intake can cause anemia
 Calcium = low intake linked to osteoporosis
 Potassium = low intake linked to elevated blood pressure
and bone mineral loss
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Water—A Vital Component
 Human body is composed of about 60% water; you
can live only a few days without water
 Foods and fluids you consume provide 80–90% of
your daily water intake
 Adequate intake to maintain hydration:
 Women need to drink about 9 cups of fluid per day
 Men need to drink about 13 cups of fluid per day
 Drink in response to thirst; consume additional fluids
for heavy exercise
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Other Substances in Food:
Antioxidants
 Antioxidant = a substance that protects against the
breakdown of body constituents by free radicals;
actions include binding oxygen, donating electrons to
free radicals, and repairing damage to molecules
 Free radical = a chemically unstable, electron-seeking
compound that can damage cell membranes and mutate
genes in its search for electrons
 Many fruits and vegetables are rich in antioxidants such
as vitamin C, vitamin E, selenium, and carotenoids
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Should You Take Supplements?
 The Food and Nutrition Board recommends
supplements only for certain groups:
 Folic acid for women capable of becoming pregnant (400
µg/day)
 Vitamin B-12 for people over age 50 (2.4 mg/day)
 Other possible situations for supplements:
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Vitamin C for smokers
Iron for menstruating women
Vitamin K for newborns
People with certain special health concerns
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Leading Sources of Calories
in the American Diet
1. Regular soft drinks (7.1% of total calories)
2. Cake, sweet rolls, doughnuts, pastries (3.6%)
3. Hamburgers, cheeseburgers, meat loaf (3.1%)
4. Pizza (3.1%)
5. Potato chips, corn chips, popcorn (2.9%)
6. Rice (2.7%)
7. Rolls, buns, English muffins, bagels (2.7%)
8. Cheese or cheese spread (2.6%)
9. Beer (2.6%)
10. French fries, fried potatoes (2.2%)
Source: Block, G. 2004. Foods contributing to energy intake in the U.S.: Data from NHANES III and NHANES 1999–2000. Journal of Food
Composition and Analysis 17: 439–447.
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Alternative Food Plans:
Healthy Eating Pyramid
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Alternative Food Plans:
Canada’s Food Guide
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Dietary Challenges for Special
Population Groups: Athletes
 Energy intake—adequate calories and nutrients
 Carbohydrates—60 to 65% of total daily calories for
most athletes, up to 70% for endurance athletes
 Protein (grams per day per kilogram of body weight)
 Endurance athletes: 1.2 to 1.4 grams
 Heavy strength training: 1.6 to 1.7 grams
 Fluids—remain hydrated
 14 to 22 oz of fluid two hours before strenuous event
 6 to 12 oz every 15–20 minutes during exercise
 Replace fluids after event (check body weight)
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A Personal Plan: Applying
Nutritional Principles
 Assess your current diet
 Set goals for change
 Try additions and substitutions to bring your
current diet closer to your goals
 Plan ahead for challenging situations
Make smart choices about nutrition! See the
following recommendations.
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What Type of Food Should People Choose?
The type of food that people eat is just as important as the
amount.
 Eat at least one dark green and one orange vegetable each
day.
 Have vegetables and fruit more often than juice.
 Make at least half of your grain products whole grain each
day.
 Drink skim, 1% or 2% milk each day.
 Have meat alternatives such as beans, lentils and tofu often.
 Eat at least two Food Guide Servings of fish each week.
 Include a small amount of unsaturated fat each day.
 Satisfy your thirst with water.
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Lowering fat
 It is best to reduce the total amount of fat in your diet and
reduce the amount of saturated and trans fats you
consume.
 Higher fat foods are often higher in saturated and trans
fats. These kinds of fats put people at higher risk of
cardiovascular disease.
 Saturated fats are found in fatty meats, higher fat milk
products, butter, lard, shortening, hard margarines and
tropical oils such as coconut and palm oil.
 Trans fats are found in many deep-fried foods, fast foods,
salty snacks and baked goods made with shortening or
partially hydrogenated vegetable oils.
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Lowering salt
 Most people get more sodium than they need,
especially if they eat packaged, processed foods and
meals made outside of the home.
 Some of the foods that can be high in sodium include
snack foods, such as crackers, nachos, potato chips
and pretzels, cheese, gravies and sauces, processed
luncheon meats, canned or dried soups and frozen
meals.
 People should compare the Nutrition Facts table on
similar products and choose the one that has a lower
number for the % Daily Value of sodium.
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Lowering sugar
 Baked goods and desserts, such as cakes, candies,
chocolate, cookies, doughnuts, ice cream, muffins,
pastries and pies, and sweetened cold and hot
beverages, such as energy drinks, fruit flavoured
drinks, soft drinks, sports drinks, hot chocolate and
specialty coffees, can be high in sugar and should be
limited.
When cooking, try roasting, grilling, baking, stir-frying,
steaming or poaching - all methods that require little
or no added fat. For tips on preparing foods with little
or no added fat, sugar or salt.
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Remember
 Think before you eat!
 Move! (energy balance)
 Make a plan for yourself – it is your body, your
health!
 Enjoy your life but do it in a smart way!
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