Nutrition
Chapter Eight
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Nutritional Requirements:
Components of a Healthy Diet
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Essential nutrients are substances the body must
get from food because it cannot manufacture them
at all or fast enough to meet its needs
There are 45 essential nutrients broken down into
6 classifications:
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Proteins
Carbohydrates
Fats
Vitamins
Minerals
Water
A kilocalorie is the amount of energy required to raise
1 liter of water 1 degree Celsius
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Proteins—The Basis of Body
Structure
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Proteins form key parts of the body’s main
structural components—muscles and bones—
and of blood, enzymes, cell membranes, and
some hormones
The building blocks of protein are amino acids
Types of Protein
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Complete (meat sources)
Incomplete (plant sources)
Adequate daily protein intake for adults is .83
grams/kg of body weight
1 gram of protein = 4 kcals
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Fats—Essential in Small
Amounts
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Fats, also known as lipids, supply energy, insulate the
body, support and cushion organs, absorb fat-soluble
vitamins, add flavor and texture to foods
Types of fats
 Saturated (see Figure 8.2)
 Unsaturated
 Monounsaturated
 Polyunsaturated
Recommended intake:
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<30% of total calories
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<10% saturated
<20% unsaturated
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Trans Fatty Acids
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Trans fats is an unsaturated fatty acid produced
during the process of hydrogenation
Hydrogenation is a process which hydrogen is
added to unsaturated fats, turning liquid fats into
solids
Many prepared foods use this process
In large amounts, trans fats can lower HDL (good
cholesterol) levels and promote the risk of heart
disease
For heart health, it is important to limit your
consumption of both saturated and trans fats by
examining ingredients in food products
1 gram of fat = 9 kcals
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Types of fatty acids and their
possible effects on health
Figure 8.3
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Fats and Health
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Many studies have examined the role of dietary
fats on blood cholesterol levels and the risk of
heart disease
Most Americans consume more saturated fats that
trans fats, which can raise LDL (low density
lipoprotein/bad cholesterol) and lower HDL (high
density lipoprotein/good cholesterol
Monounsaturated fatty acids and polyunsaturated
fatty acids improve cholesterol levels and have a
number of heart healthy effects
In addition to heart disease risk, dietary fats from
red meat can raise the risk of cancer, especially
colon cancer
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Carbohydrates—An Ideal
Source of Energy
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The primary function of dietary carbohydrate is to
supply energy to body cells.
Caloric value:
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4 calories/gram
There are two main types:
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Simple (one or two sugar units/molecule)
Complex (more than two sugar units/molecule)
Recommended levels:
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225-325 grams based on a 2000 calorie intake/day
Carbohydrates are broken down into glucose, its
simplest form
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Refined Carbohydrates vs.
Whole Grains
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Whole grains have higher nutritional values
compared to refined carbohydrates in the
following:
 fiber, vitamins, minerals, and other beneficial
compounds
Whole grains (unrefined carbs) take longer to
chew and digest, resulting in:
 making people feel full sooner
 entering the bloodstream more slowly
 reducing the possibility of overeating
 slower rise of blood sugar
See the box, “Take Charge”
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Glycemic Index
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Glycemic index is a measure of how the ingestion
of a particular food affects blood glucose levels
Foods with a high glycemic index cause quick and
dramatic rise in blood sugar levels
Diets rich in high glycemic index foods are linked
to increased risk of diabetes and heart disease,
as well as increasing caloric intake
High fiber foods and unrefined carbohydrates
tend to have a lower glycemic index
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What is Fiber?
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Dietary fiber are indigestible carbohydrates that are intact
in plant sources
Fiber passes through the intestinal tract and provides bulk
for feces, assisting with bowel elimination
Types of fiber
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Sources of Dietary Fiber
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Soluble fiber: slows the body’s absorption of glucose, binding
cholesterol-containing compounds in the intestines
Insoluble fiber: binds with water, allowing fecal matter to
become bulkier and softer
All plant food contain fiber, however, fruits, legumes, and oats
contain higher amounts
RDA for Fiber
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38 grams for adult men
25 grams for adult women
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Vitamins—Organic
Micronutrients
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Vitamins are organic (carbon-containing)
substances needed in small amounts to help
promote and regulate chemical reactions and
processes in body cells.
Types of Vitamins:
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fat-soluble (A, D, E, and K)
water-soluble (C and the eight B-complex vitamins:
thiamin, riboflavin, niacin, vitamin B-6, folate, vitamin B12, biotin, and pantothenic acid)
Sources of Vitamins
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Vitamins are abundant in fruits, vegetables, and grains;
they are also added to some processed foods
See Table 8.2
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Minerals—Inorganic
Micronutrients
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Minerals are 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 (those needed in small
amounts) include:
 copper, fluoride, iodide, iron, selenium, and
zinc
See Table 8.3
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Water
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The human body is composed of about 60% water;
you can live only a few days without water
Water is used in digestion and absorption in food
and is the medium for most chemical reactions that
take place in the body
The recommended amounts needed are:
 Women need to drink about 9 cups of fluid per
day
 Men need to drink about 13 cups of fluid per day
Since water is lost everyday through urine, feces,
sweat, and evaporation, consuming adequate
amounts are needed daily
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Other Substances in Food:
Antioxidants
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Antioxidants are substances 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 radicals are chemically unstable, electron-seeking
compounds 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
Antioxidants also fall into a broader category of phytochemicals,
substances found in plant food that help prevent chronic
diseases
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Nutritional Guidelines:
Planning Your Diet
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Various tools have been created by scientific and
government groups to help people design healthy
diets
The following are considered guidelines to use as a
reference:
 Dietary Reference Intakes (DRIs)
 Dietary Guidelines for Americans
 MyPyramid
 DASH
* Include appropriate figures/tables to follow
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The Vegetarian Alternative
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Types of vegetarian diets
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Vegan = vegetarian who eats no animal products
Lacto-vegetarian = vegetarian who includes milk
and cheese products in the diet
Lacto-ovo-vegetarian = vegetarian who includes
milk and cheese products and eggs in the diet
Partial vegetarian, semivegetarian, or
pescovegetarian = vegetarian who includes eggs,
dairy products, and small amounts of poultry and
seafood in the diet
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Dietary Challenges for
Special Population Groups
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Some populations face special dietary
challenges, including:
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Women lacking nutrient density foods, calcium, iron
Men needing more fruits, vegetables, grains
College students should improve overall quality of food
choices
Older adults need nutrient density foods, fiber, vitamin
B-12
People with special health concerns should discuss this
with their physician or dietitian
Athletes need increased energy and fluid requirements
See the box, “Take Charge”
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Nutritional Planning: Making
Informed Choices About Food
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Read Food labels
Read Dietary
supplement labels
Be Aware of Food
additives
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Be Vigilant for
Foodborne illness
Understand
Environmental
Contaminants and
Organic Foods
Identify Irradiated
Foods
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Food Additives
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Most widely used are sugar, salt, corn
syrup, citric acid, baking soda, vegetable
colors, mustard, pepper
Concerns about some additives:
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Monosodium glutamate (MSG) causes some
people to experience episodes of sweating and
increased blood pressure
Sulfites cause severe reactions in some people
Check food labels
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Guidelines for Fish
Consumption
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To avoid harmful effects of mercury, guidelines have been set
for women who are or who may become pregnant, as well as
nursing mothers:
 Do not eat shark, swordfish, king mackerel, tilefish
 Eat up to 12 ounces per week of a variety of fish and
shellfish; limit consumption of albacore tuna to 6 ounces
per week
 Check advisories about locally caught fish; if no
information is available, limit to 6 ounces per week
Follow the same guidelines for children, but in smaller
servings
To avoid exposure to PCBs in farmed fish, some experts
recommend a limit of 8 ounces of farmed salmon per month
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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
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