Transcript Ch03 Nutrition

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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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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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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:
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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)
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Daily values
Dietary Guidelines for Americans
MyPyramid
DASH
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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
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.
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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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