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Nutritional Requirements:
Components of a Healthy Diet
• 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:
–
–
–
–
–
–
Proteins
Carbohydrates
Fats
Vitamins
Minerals
Water
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Nutritional Requirements:
Components of a Healthy Diet
• Six classes of essential nutrients, three supply
energy:
– Fat = 9 calories per gram
– Protein = 4 calories per gram
– Carbohydrate = 4 calories per gram
• One kilocalorie represents the amount of heat it takes to
raise the temperature of 1 liter of water 1 degree
centigrade
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Figure 8.1 The Digestive System
page 216
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Proteins—The Basis of Body
Structure
• 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
– Complete (meat sources)
– Incomplete (plant sources)
• Adequate daily protein intake for adults is .8 grams per kg
of body weight
• AMDR for protein for adults is 10-35% of total daily calories
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Fats—Essential in Small
Amounts
• 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
– Unsaturated
• Monounsaturated
• Polyunsaturated
• Recommended intake:
– Men
• 17 g of linoleic acid and 1.6 g of alpha-linoleic acid
– Women
• 12 g of linoleic acid and 1.1 g of alpha-linoleic acid
• AMDR for total fat is 20-35% of total calories
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Figure 8.2 Chemical Structures of Saturated
and Unsaturated Fatty Acids
page 219
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Trans Fatty Acids
• Trans fat is an unsaturated fatty acid produced during the
process of hydrogenation
• Hydrogenation is a process in 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
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Fats and Health
• 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 than trans
fats, both of which can raise LDL (low density
lipoprotein/bad cholesterol)
• Monounsaturated fatty acids and polyunsaturated fatty
acids improve cholesterol levels and have a number of
heart healthy effects
– Omega-3 and 6
• In addition to heart disease risk, dietary fats from red
meat can raise the risk of cancer, especially colon
cancer
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Figure 8.3 Types of fatty acids and their possible
effects on health
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Carbohydrates—An Ideal Source of
Energy
• The primary function of dietary carbohydrate is to supply
energy to body cells.
• Caloric value:
– 4 calories/gram
• There are two main types:
– Simple (one or two sugar units/molecule)
– Complex (more than two sugar units/molecule)
– Recommended levels:
• 225-325 grams based on a 2000 calorie intake/day
• AMDR recommends 45-65% of total daily calories
• Carbohydrates are broken down into glucose, its simplest
form
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Refined Carbohydrates vs. Whole
Grains
• 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
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Glycemic Index and Glycemic
Response
• 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?
• Dietary fiber is the term for 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
– 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
• Sources of Dietary Fiber
– All plant food contain fiber; however, fruits, legumes, and oats contain
higher amounts
• RDA for Fiber
– 38 grams for adult men
– 25 grams for adult women
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Vitamins—Organic
Micronutrients
• 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:
– fat-soluble (A, D, E, and K)
– water-soluble (C and the eight B-complex vitamins: thiamin,
riboflavin, niacin, vitamin B-6, folate, vitamin B-12, biotin, and
pantothenic acid)
• Sources of Vitamins
– Vitamins are abundant in fruits, vegetables, and grains; they are
also added to some processed foods
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Minerals—Inorganic
Micronutrients
• 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
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Water
• 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
• Recommendedations:
– Women need to drink about 9 cups (2.2 liters) of fluid
per day
– Men need to drink about 13 cups (3.7 liters) of fluid per
day
• Water is lost every day through urine, feces, sweat, and
evaporation.
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Other Substances in Food:
Antioxidants
• Antioxidants are substances that protect 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 foods that help prevent chronic diseases
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Nutritional Guidelines: Planning
Your Diet
• 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)
• Recommended Dietary Allowance (RDA)
• Adequate Intake (AI)
–
–
–
–
Daily values
Dietary Guidelines for Americans
MyPyramid
DASH
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Figure 8.5 USDA’s MyPyramid
page 233
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The Vegetarian Alternative
• Types of vegetarian diets
– Vegans = vegetarian who eats no animal products
– Lacto-vegetarians = vegetarian who includes milk and
cheese products in the diet
– Lacto-ovo-vegetarians = vegetarian who includes milk,
cheese products, and eggs in the diet
– Partial vegetarians, semivegetarians, or
pescovegetarians = vegetarian who includes eggs, dairy
products, small amounts of poultry and seafood in the
diet
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Dietary Challenges for Special
Population Groups
• Some populations face special dietary challenges,
including:
– Women lacking nutrient-dense foods, calcium, iron
– Men needing more fruits, vegetables, grains
– College students should improve overall quality of food
choices
– Older adults need nutrient-dense 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
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Nutritional Planning: Making
Informed Choices About Food
• Read food labels
• Read dietary
supplement labels
• Food additives
• Foodborne illness
• Irradiated foods
• Environmental
contaminants and
organic foods
– pathogens
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Food Additives
• Most widely used are sugar, salt, corn syrup,
citric acid, baking soda, vegetable colors,
mustard, pepper
• Concerns about some additives:
– 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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Figure 8.4 Nutrient density of 12-ounce portions
of selected beverages—page 232
Note that regular soda is the leading source of both
added sugars and calories in the American diet, but
it provides few nutrients except sugar.
(c) 2011 McGraw-Hill Higher Education. All rights reserved.
25
Guidelines for Fish Consumption
• 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
• Assessing and changing your diet
• Staying committed to a healthy diet
• Try additions and substitutions to bring
your current diet closer to your goals
• Plan ahead for challenging situations
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Chapter Eight
NUTRITION
Chapter 8
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