Chapter Eight (c) 2013 McGraw-Hill Higher Education. All rights reserved.
Mar 26, 2015
Chapter Eight
(c) 2013 McGraw-Hill Higher Education. All rights reserved.
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 six 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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The Digestive System
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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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Refer to Table 8.2 for popular foods and the amount of protein
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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, and add flavor and texture to foods
Types of fats: Saturated Unsaturated
Monounsaturated Polyunsaturated
Hydrogenation Trans fatty acids
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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The Parts of a Whole Grain Kernel
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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 (increase levels of high-density lipoprotein (HDL)) and have a number of heart healthy effects Omega-3
Primary fish Dark green leafy vegetables Walnuts and flaxseeds Canola oil
Omega -6 Corn and soybean oil
In addition to heart disease risk, dietary fats from red meat can raise the risk of cancer, especially colon cancer
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Types of Fatty Acid
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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 nondigestible
carbohydrates that are intact in plant sources Functional Fiber is the term for nondigestible
carbohydrates has been isolated or synthesized in a lab and then added to food as a supplement.
Fiber passes through the intestinal tract and provides bulk for feces, assisting with bowel elimination
Types of fiber Soluble (viscous) 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
Recommendations: 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 ChooseMyPlate (new 2010 USDA Dietary
Guidelines) DASH
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Nutrient Density of 12-ounce Portions of Selected Beverages
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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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MyPlate Food Intake Patterns
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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 Athletes need increased energy and fluid
requirements People with special health concerns should
discuss this with their physician or dietitian23
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Nutritional Planning: Making Informed Choices About Food
Read food labels Read dietary
supplement labels Food additives Foodborne illness
pathogens
Irradiated foods Environmental
contaminants and organic foods
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Food Additives
Most widely used are sugar, salt, corn syrup, citric acid, baking soda, vegetable colors, mustard, and 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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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
(c) 2013 McGraw-Hill Higher Education. All rights reserved.