Download Chapter Five

Chapter 5
Understanding Nutrition
and Your Diet
© 2009 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
© 2009 McGraw-Hill Higher Education. All rights reserved.
Carbohydrates
Major energy source: 4 calories/gram
 Types

Monosaccharides
 Disaccharides
 Polysaccharides


Recommended intake: 45-65% of
total calories from carbohydrates
© 2009 McGraw-Hill Higher Education. All rights reserved.
Carbohydrates

Simple sugars

Average American adult consumes
about 140 pounds of sweeteners
each year
 Sugar,
corn sweetener, syrup, honey
 Sodas, candy, bakery and processed
goods
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
Composition of Dietary Fats
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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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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

© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
Fats
Low-fat foods



Low-fat does not
necessarily mean
low-calorie
Higher price tag
Low-fat dairy and
salad dressings have
less saturated fat
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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

© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
Dietary Reference Intakes

Dietary Reference Intakes (DRIs) =
recommended nutrient intakes




Estimated Average Requirement (EAR)
Recommended Dietary Allowance (RDA)
Tolerable Upper Intake Level (UL)
Acceptable Macronutrient Distribution Range
(AMDR)—percent of total daily calories
 45-65%
as carbohydrate
 20-35% as fat
 10-35% as protein
© 2009 McGraw-Hill Higher Education. All rights reserved.
Tools for Planning a
Healthy Diet

The USDA Food Guide:
MyPyramid

The Dietary Guidelines for
Americans
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid
© 2009 McGraw-Hill Higher Education. All rights reserved.
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid

Personalized approach
Amounts recommended from each food
group vary based on age, gender, and
activity level
 Visit www.mypyramid.gov


Balance food intake and physical
activity
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid Food Groups

Fruits




2 cups/day for a 2,000-calorie diet
Eat a variety of fruits
Favor whole fruits over fruit juices
Vegetables


2½ cups/day for a 2,000-calorie diet
Eat a variety of vegetables





Dark green vegetables
Orange vegetables
Legumes
Starchy vegetables
Other vegetables
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid Food Groups

Milk and milk products
3 cups/day for a 2,000-calorie diet
 Favor fat-free or low-fat products
 Vegans and those who are lactose
intolerant should choose other sources of
calcium

© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid Food Groups

Meat, poultry, fish, eggs, dry
beans, and nuts
5 1/2 ounce-equivalents for a 2,000calorie diet
 1 ounce equivalents:

1
ounce cooked meat, poultry, fish
 1 egg
 1/4 cup legumes or tofu
 1 tablespoon peanut butter
 1/2 ounce nuts or seeds

Choose lean and low-fat foods
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid Food Groups

Breads, cereals, rice, and pasta
6 ounces/day for a 2,000-calorie diet
 3 or more ounces/day should be whole
grains


1 ounce equivalents:
1
slice bread
 1 cup dry cereal
 1/2 cup cooked rice, pasta, cereal
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid Food Groups

Oils (vegetable oils, fish, nuts, seeds)
24 grams or 6 teaspoons/day for a
2,000-calorie diet
 1 teaspoon equivalents:

1
teaspoon vegetable oil or margarine
 1 tablespoon low-fat mayonnaise
 2 tablespoons light salad dressing

Discretionary calories
© 2009 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Adequate nutrients within calorie
needs


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

© 2009 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Physical activity

Regular moderate physical activity
 30
minutes/day to reduce risk of chronic
disease
 60 minutes/day to prevent gradual,
unhealthy weight gain
 60-90 minutes/day to sustain weight loss

Decrease sedentary activities
© 2009 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Food groups to encourage




Fruits
Vegetables
Milk
Fats




Total fat: 20-35% of total calories
Saturated fat: <10% of total
calories
Cholesterol: <300 mg/day
Limit trans fats
© 2009 McGraw-Hill Higher Education. All rights reserved.
Dietary Guidelines for
Americans

Carbohydrates
Choose whole grains often
 Limit added sugars


Sodium and potassium
Sodium: Consume less than 2,300 mg/day
(about 1 teaspoon of salt)
 Potassium: Consume potassium-rich foods
such as fruits and vegetables

© 2009 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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
MyPyramid for
Ovolactovegetarians
© 2009 McGraw-Hill Higher Education. All rights reserved.
Food Labels
Required by the FDA
since 1973
 New in 2006

Amount of trans fat
 Proteins derived from
major food allergen
sources

© 2009 McGraw-Hill Higher Education. All rights reserved.
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 by as
much as 500 calories
© 2009 McGraw-Hill Higher Education. All rights reserved.
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

© 2009 McGraw-Hill Higher Education. All rights reserved.
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
Cannot claim to cure or treat diseases
 Americans
spent over $19 billion on
supplements (in 2005)
© 2009 McGraw-Hill Higher Education. All rights reserved.
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
© 2009 McGraw-Hill Higher Education. All rights reserved.
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

© 2009 McGraw-Hill Higher Education. All rights reserved.
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

© 2009 McGraw-Hill Higher Education. All rights reserved.
Food Safety

Food additives
Provide color or flavor
 Replace sugar or fat
 Improve nutritional content, texture,
or shelf life
 FDA tested


Genetically modified foods

Altered to improve yields and reduce
costs
© 2009 McGraw-Hill Higher Education. All rights reserved.
Chapter Five:
Understanding Nutrition and Your Diet
© 2009 McGraw-Hill Higher Education. All rights reserved.