Chapter Five:
Understanding Nutrition
and Your Diet
© 2013 McGraw-Hill Higher Education. All rights reserved.
Nutrients
•
Nutrients = elements in food that are
required for the growth, repair, and
regulation of body processes
1. Carbohydrates
2. Fats
3. Protein
4. Vitamins
5. Minerals
6. Water
7. Fiber
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Energy from Food
Calorie = unit of energy
 1 calorie = amount of energy needed
to raise the temperature of 1 gram of
water by 1 degree Celsius
 In common usage, “calorie” refers to
“kilocalorie” (1,000 calories)
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Carbohydrates
Major energy source: 4 calories/gram
 Types

Monosaccharides
 Disaccharides
 Polysaccharides


Recommended intake: 45-65% of
total calories from carbohydrates
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Carbohydrates

Simple sugars

Average American adult consumes about
156 pounds of sweeteners each year



Sugar, corn sweetener, syrup, honey
Sodas, candy, bakery and processed goods
Sugar substitutes







Saccharin
Aspartame
Sucralose, tagatose
Sorbitol, xylitol
Acesulfame potassium
Neotame
Stevia
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Fats



Functions: Insulation, carrier of
vitamins, storage of long-term energy,
and satiety
Energy source: 9 calories/gram
Types





Saturated
Monounsaturated
Polyunsaturated
Trans
Recommended intake: 20-35% of
total calories
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Types of Fats

Saturated fats




Solid at room temperature
Primarily found in animal fats
Negative effects on heart health
Monounsaturated and polyunsaturated fats




Liquid at room temperature
Vegetable oils
Positive effects on heart health
Omega-3 polyunsaturated fats found in fish are
considered especially healthful
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Fatty Acid Profiles of
Common Fats and Oils
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Types of Fats: Trans Fats
Altered form of unsaturated fat
(hydrogen added)
 Associated with unhealthy changes in
cell membranes
 Raises levels of “bad” cholesterol and
lowers levels of “good” cholesterol
 Found in margarine, snack foods, and
some deep fried fast foods


Check food labels
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Types of Fats: Cholesterol
White fatlike substance found in
cells of animal origin
 Functions: Synthesizes cell
membranes; starting material in
formation of hormones and bile
 The liver can synthesize cholesterol
 Excess cholesterol in the body can
clog arteries and increase risk of
cardiovascular disease

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Fats
Low-fat foods



Fat substitutes
Low-fat does not
necessarily mean
low-calorie
Higher price tag
Low-fat dairy and
salad dressings have
less saturated fat



Simplesse, Olestra
Fats cannot be
broken down and
absorbed by body
Unpleasant side
effects
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Fats: General
Recommendations





20-35% of total daily calories from fat
Less than 10% of calories from
saturated fat
Less than 300 mg/day of cholesterol
Keep trans-fatty acid consumption as
low as possible
Get most fats from sources of
unsaturated fats



Fish
Nuts
Vegetable oils
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Protein
Functions: Growth and maintenance
of tissue, acid-base balance
 Energy source: 4 calories/gram
 Amino acids = building blocks of
protein


11 can be built by the body
 Nonessential

amino acids
9 must be obtained from food
 Essential
amino acids
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Protein

Complete protein sources supply all
essential amino acids


Incomplete protein sources supply
some but not all essential amino acids


Animal foods, soybeans
Plant foods
Recommended intake: 10-35% of
total calories
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Vitamins




Organic compounds needed in small
amounts for normal growth,
reproduction, and maintenance of health
Serve as co-enzymes
Provide no energy: 0 calories/gram
Types

Water soluble


B-complex vitamins and vitamin C
Fat soluble

Vitamins A, D, E, K
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Vitamins: Should I Take a
Supplement?

Following dietary recommendations would
allow most Americans to meet their
nutrient needs without supplements


Caution with using supplements



Many people eat too many nutrient-deficient
foods
Hypervitaminosis = toxicity
Megadoses of any vitamin can be harmful
Recommendations for certain groups

Folic acid, vitamin B-12, vitamin D
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Phytochemicals


Phytochemicals = physiologically active
components of foods that may
deactivate carcinogens
Many phytochemicals function as
antioxidants


May protect cells from damage caused by
unstable molecules (“free radicals”)
Examples



Carotenoids
Polyphenols
Allyl sulfides
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Minerals
Inorganic materials that act as
structural elements and regulators of
numerous body processes
 Provide no energy: 0 calories/gram
 Types

Macronutrients: “Major minerals” found in
high amounts in the body
 Micronutrients: “Trace elements” found in
small amounts in the body

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Water and Fluids

Average adult loses about 10 cups of water
per day




Urination, bowel movements, breathing,
perspiration
Functions: Provide medium for nutrients,
waste transport, temperature control
For every pound of body weight, you need
about 0.5 ounce of fluid
Sources: Beverages, fruits, vegetables
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Fiber



Cellulose-based plant material that
cannot be digested
Provides no energy: 0 calories/gram
Types:



Benefits




Soluble (gel-forming)
Insoluble (absorbs water)
Moves stool through digestive tract
Lowers blood cholesterol levels
Steadies blood sugar levels
Recommended: 21-38 grams/day

Most American adults: 11 grams/day
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The Digestive System: The
Absorption of Nutrients
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Tools for Planning a
Healthy Diet

The USDA Food Guide:
MyPlate

The Dietary Guidelines for
Americans
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MyPlate
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10 Tips to a Great Plate
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MyPlate Food Groups –
Fruits

Fruit Recommendations


¼ of the plate should be filled with fruit
The specific amount of fruit depends on gender and age. See table
5.2.
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MyPlate Food Groups –
Vegetables

Vegetable Recommendations


¼ of the plate should be filled with vegetables
The specific amount of vegetables depends on gender and age. See
table 5.2.
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MyPlate Food Groups – Dairy

Dairy Recommendations


3 cups of fat-free or low-fat milk per day, or the equivalent in
another dairy product
The specific amount of dairy for children depends on age. See table
5.2.
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MyPlate Food Groups –
Protein

Protein Recommendations



5-6 ounces of protein should be consumed every day.
Choose lean, low-fat foods.
See table 5.2 for gender- and age-specific recommendations.
© 2013 McGraw-Hill Higher Education. All rights reserved.
MyPlate Food Groups –
Grains

Grain Recommendations


See table 5.2 for gender- and age-specific recommendations.
1 ounce is equivalent to



1 slice bread
1 cup dry cereal
½ cup cooked rice, pasta, cereal
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Oils

Oils (vegetable oils, fish, nuts, seeds)
24 grams or 6 teaspoons/day for a
2,000-calorie diet (see Table 5.2)
 1 teaspoon equivalents:

1
teaspoon vegetable oil or margarine
 1 tablespoon low-fat mayonnaise
 2 tablespoons light salad dressing

Discretionary calories
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Dietary Guidelines for
Americans

Focus on Nutrient Density


Consume nutrient-dense foods within
and among the food groups
Weight management
Balance calories from foods and
beverages with calories expended
 Make small decreases in calorie intake to
prevent gradual weight gain over time

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Dietary Guidelines for
Americans

Physical activity

Regular moderate physical activity
2
hours and 30 minutes of moderateintensity aerobic activity spread over 3 days
per week

Decrease sedentary activities
© 2013 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Food groups to encourage
Fruits
 Vegetables
 Dairy
 Seafood

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Dietary Guidelines for
Americans

Foods to Limit


Fats, Sugars, Sodium, and Alcohol
Fats

Most fat calories should come from
polyunsaturated and monounsaturated
fats
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Dietary Guidelines for
Americans

Sugar consumption


Choose and prepare foods with little added
sugar
Sodium Intake
Sodium: Consume less than 2,300 mg/day
(about 1 teaspoon of salt)
 Too much sodium is linked to hypertension

© 2013 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Alcoholic beverages

Those who choose to drink should do so
sensibly and in moderation
 Up
to 1 drink/day for women
 Up to 2 drinks/day for men

Food safety

Take steps to avoid microbial foodborne
illness
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Vegetarian Diets

Reliance on plant sources for most of the
nutrients the body needs




Ovovegetarian: Includes eggs
Lactovegetarian: Includes dairy
Ovolactovegetarian: Includes eggs and dairy
Vegan: Excludes all animal products



Requires more planning
Need to maintain adequate intake of vitamin B-12,
calcium, iron, zinc, vitamin D
Semivegetarian: Great reduction (but not
elimination) of meat products

Pescovegetarian: Includes fish, eggs, dairy products
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Nutrition and the Older Adult
Older adults may find food less
tasteful, harder to chew
 Lower energy requirements
 Psychosocial factors

Social isolation
 Depression
 Alcohol consumption
 Limited transportation

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Food Labels


Required by the FDA
since 1973
New in 2006



Amount of trans fat
Proteins derived from major food
allergen sources
New in 2008

The “Country of Origin”
legislation requires fresh or
frozen meats, fish, fruits, and
vegetables to identify country of
origin.
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Nutrition
Facts Label
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Fast Foods

Fat density of fast foods
40-70% of calories in fast foods is fat
 Recommended intake: 20-35% of total
daily calories from fat


Most people underestimate the calorie
content in a fast food meal
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Functional Foods

Foods capable of contributing to the
improvement or prevention of specific
health problems
Probiotics: Living bacteria that help
prevent disease and strengthen the
immune system (e.g., yogurt)
 Garlic, olive oil, high-fiber foods, calciumrich foods, antioxident-rich foods
 Foods enriched with folic acid

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Dietary Supplements





Products that supplement the total daily
intake of nutrients in the diet
Ingested in tablet, capsule, softgel, gelcap,
and liquid form
Not in themselves used as conventional
foods or as the only items in a meal or diet
Must be deemed safe for human use
Cannot claim to cure or prevent illnesses
 Exceptions:
Folic acid, calcium
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Food Allergies

Allergy = reaction in which the immune
system attacks an otherwise harmless
food or ingredient



Different from a food intolerance, which is
usually caused by an enzyme deficiency
Common food allergens include peanuts,
milk, soy products, shellfish, and wheat
Allergic reactions can develop slowly over
several exposures

Symptoms range from mildly unpleasant to
life threatening
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Food Safety

Preventing
foodborne
illness

Safe handling,
cooking, and
storage of
foods
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Food Safety

Food irradiation


Use of radiation to kill foodborne
pathogens
Safe farming techniques
More humane treatment of farm animals
 Improved food quality
 Reduced exposure to antibiotic-resistant
bacteria, prions (cause of “mad cow
disease”), and chemicals

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Food Safety

Organic foods
No use of growth
hormone or antibiotics
 Not genetically
engineered or irradiated
 No use of chemical
fertilizers or sewage
sludge
 Diseases, pets, and
weeds treated or
controlled primarily with
nonchemical means

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Food Safety

Food additives
Provide color or flavor
 Improve nutritional content, texture,
or shelf life
 FDA tested
 Questionable additives: aspartame,
stevia, and some food colorings


Genetically modified foods

Altered to improve yields and reduce
costs
© 2013 McGraw-Hill Higher Education. All rights reserved.
Chapter Five:
Understanding Nutrition and Your Diet
© 2013 McGraw-Hill Higher Education. All rights reserved.