Transcript Chapter 5

Chapter 5
Nutrition
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1
Understanding Nutritional
Guidelines
• Dietary Reference Intakes (DRIs):
umbrella term for four sets of dietary
recommendations
– Suggested intake levels of essential nutrients for
optimal health
• Recommended Dietary Allowance (RDA):
represents the average daily amount of any
one nutrient to protect against nutritional
deficiency
• Acceptable Macronutrient Distribution
Range (AMDR): intake levels of essential
nutrients that provide adequate nutrition and
reduce risk of chronic disease
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2
Understanding Nutritional
Guidelines
• Dietary Guidelines for Americans:
scientifically based diet and exercise
recommendations
• USDA MyPlate: graphic nutritional tool that
translates DRIs and Dietary Guidelines into
healthy food choices
• Daily Values: standards used on food labels
to indicate how a particular food contributes
to the recommended daily intake of major
nutrients in a 2,000-calorie diet
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3
Types of Nutrients
• Essential nutrients: needed to build,
maintain, and repair tissues and regulate
body functions
• Macronutrients: needed in large amounts
– Water, carbohydrates, proteins, fats
• Micronutrients: needed in small amounts
– Vitamins, minerals
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Water—The Unappreciated
Nutrient
• Function:
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Digests, absorbs, transports nutrients
Helps regulate body temperature
Carries waste out of the body
Lubricates our body parts
• Fluid balance: right amount of fluid inside
and outside each cell; maintained by
electrolytes
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5
Water—The Unappreciated
Nutrient
• In most places in U.S. tap water is of equal
or superior quality to bottled water
• RDA:
– 1 to 1.5 milliliters per calorie spent
– 2 to 3 liters, or 8 to 12 cups of fluid
– Water needs can vary depending on several
factors, such as foods consumed and activity
level
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6
Carbohydrates—Your
Body’s Fuel
– The body’s main source of energy
– Fuel most of the body’s cells during daily activities
– Used by muscle cells during high-intensity
exercise
– Only source of energy for brain cells, red-blood
cells, and some other types of cells
• Types:
– Simple carbohydrates (sugars)
– Complex carbohydrates (starches and dietary
fibers)
• RDA:
– 130 grams for males and females (aged 1–70)
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Simple and Complex
Carbohydrates
• Simple carbohydrates:
– Easily digestible and composed of one or two units
of sugar
• Glucose, fructose, galactose, lactose, maltose,
sucrose
• Glucose travels to liver where it can be stored
as glycogen for future energy needs
• Too many simple carbohydrates leaves you with
a “sugar high”, followed by a feeling of depletion,
and a craving for more sugar
– Added sugars have even more dramatic effect
– High fructose corn syrup (HFCS)
• Artificial sweeteners touted as alternative
– Safety concerns; effect on appetite and insulin
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Simple and Complex
Carbohydrates
• Complex carbohydrates:
– Composed of multiple sugar units including
starches and dietary fiber
– Sources:
• Whole grains (whole wheat, brown rice, oatmeal,
corn)
• Vegetables; some fruit
– Whole grains preferred over refined
carbohydrates (white flour products)
• Provide more nutrients
• Slow digestive process
• Make you feel full longer
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Fiber
• Dietary fiber: complex carbohydrate found in
plants that cannot be broken down by the
digestive tract
• Fiber allows for passage of food quickly
through the intestines, which helps prevent
hemorrhoids and constipation
• Soluble fiber dissolves in water and lowers
cholesterol
• Insoluble fiber passes through digestive
tract unchanged; serves as natural laxative
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Fiber
• RDA:
– 25 grams/day for women (aged 19-50)
– 38 grams/day for men (aged 14-50)
• Fiber is best obtained through diet, not pills or
supplements
• Sources of fiber:
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Fruits
Vegetables
Dried beans
Peas and other legumes
Cereals
Grains
Nuts
Seeds
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Protein—Nutritional Muscle
• Function:
– Build and maintain muscles, bones, and other
body tissues
– Form enzymes that facilitate chemical reactions
– Constructed from 20 different amino acids
• Essential amino acids must be supplied by foods
• Types:
– Complete proteins
– Incomplete proteins
• RDA:
– 0.36 grams per pound of body weight
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Protein—Nutritional Muscle
• Complete protein sources
– Animal proteins: meat, fish, poultry, milk, cheese,
eggs
• Incomplete protein sources
– Vegetable proteins: grains, legumes, nuts, seeds,
other vegetables
• Complementary proteins: proteins that in
combination provide essential amino acids
• Mutual supplementation: nutritional strategy
of combining two incomplete protein sources
to provide a complete protein
– For example, beans and rice
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Fats—A Necessary Nutrient
• Principal form of stored energy in the body
– Provide essential fatty acids
– Role in the production of other fatty acids and
Vitamin D
– Provide the major material for cell membranes and
for the myelin sheaths that surround nerve fibers
– Assist in absorption of fat-soluble vitamins
– Affect texture, taste, and smell of foods
– Provide emergency reserve when we are sick or
when our food intake is diminished
• RDA:
– 20–35% of calories from fat with only about onethird coming from saturated fats
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Types of Fat
• Saturated fat: found in animal products and
other fats that remain solid at room
temperature
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Beef
Pork
Poultry
Whole-milk dairy products
Certain tropical oils (coconut and palm)
Certain nuts (macadamia)
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Types of Fat
• Monounsaturated fat: found primarily in
plant sources, are liquid at room
temperature, and are semisolid or solid
when refrigerated
– Olive, safflower, peanut and canola oils
– Avocados
– Many nuts
• Polyunsaturated fat: commonly referred to
as “oil”; liquid at room temperature and
when refrigerated
– Corn and soybean oils
– Fish, including trout, salmon, and anchovies
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Cholesterol
• A waxy substance that is needed for several
important body functions
• The body produces it from the liver and
obtains it from animal food sources (meat,
cheese, eggs, milk)
• Too much cholesterol can clog arteries and
lead to cardiovascular disease
• LDLs (low density lipoproteins) are the “bad”
cholesterol, while HDLs (high density
lipoproteins) are considered “good”
• Recommended: consume no more than 300
milligrams per day
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Trans Fats
• Liquid vegetable oils that have been
chemically changed through the process of
hydrogenation to extend the shelf life of
processed foods
• Pose a risk to cardiovascular health by
raising LDL levels and lowering HDL levels
• Foods high in trans fatty acids include:
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Crackers, cookies, chips
Cakes and pies
Doughnuts
Deep fried foods like French fries
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Omega-3 and Omega-6
Fatty Acids
• Omega-3s: contain alpha-linolenic acid,
which helps slow the clotting of blood,
improves arterial health, and lowers blood
pressure
• Omega-6s: contain linolenic-acid and are
important to health, though they are often
consumed too much by Americans
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Minerals—A Need for
Balance
• Minerals are naturally occurring substances
needed by the body in small amounts
– Build strong bones and teeth, and help carry out
metabolic processes and body functions
• The body needs 20 essential minerals
– Macrominerals (need at least 100 mgs/day)
• Calcium, chloride, magnesium, phosphorous,
potassium, sodium
– Microminerals (need less than 100 mgs/day)
• Chromium, cobalt, copper, fluorine, iodine, iron, zinc,
manganese, nickel, and others
• A balanced diet provides all the essential
minerals the body needs per day
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Vitamins—Small But Potent
Nutrients
• Naturally occurring organic substances
needed by the body in small amounts
• Serve as catalysts for releasing energy from
carbohydrates, proteins, and fats while
maintaining other body components
• Your body needs at least 11 specific
vitamins
– A, C, D, E, K, and the B-complex vitamins
• Vitamins can be found in a variety of foods,
so often supplements are unnecessary
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Key Vitamins and Minerals
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Overview of RDIs
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Other Substances in Food:
Phytochemicals
• Phytochemicals: substances naturally
produced by plants
• May keep cells healthy, slow tissue
degeneration, prevent carcinogens, reduce
cholesterol, protect heart, maintain hormone
levels, keep bones strong
• Three important types of phytochemicals:
– Antioxidants: neutralize free radicals
– Phytoestrogens: lower cholesterol and reduce risk
of heart disease
– Phytonutraceuticals: may inhibit growth of cancer
and heart disease
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The Color Wheel of Foods
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Dietary Guidelines for
Americans
• Two-thirds of Americans are now overweight
or obese
• Focus is on stopping and reversing the
spread of overweight and obesity
• Approaches to change:
– Individual
– Environmental
– Food supply
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Dietary Guidelines for
Americans
• Four main goals:
– Reduce calorie intake and increase physical
activity
– Move toward a more plant-based diet composed
of nutrient-dense foods
– Reduce intake of foods containing added sugars
and solid fats and reduce overall sodium and
refined grain consumption
– Meet the 2008 Physical Activity Guidelines
provided by the U.S. Department of Health and
Human Services
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2010 Dietary Guidelines for
Americans: Key Messages
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Dietary Guidelines for
Americans
• MyPlate: visual icon designed to raise
awareness and health literacy about the
different food groups
– Emphasize foods high in nutrient density
• Individual calorie requirements are
calculated based on sex and age at three
activity levels:
– Sedentary: only light physical activity
– Moderately active: equivalent to walking 1.5 miles
per day at 3–4 mph
– Active: more than 3 miles per day at 3–4 mph
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MyPlate
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Estimated Calorie
Requirements
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Dietary Guidelines for
Americans
• DASH Eating Plan: Dietary Approaches to
Stop Hypertension
• Recommendations for specific groups
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Children and adolescents
Older adults
Pregnant and breastfeeding women
Overweight adults and children
People with chronic conditions
• Limit red meat consumption
– Link to heart disease, cancer, and diabetes
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Vegetarian Diets
• Vegetarian diets may offer protection
against obesity, heart disease, high blood
pressure, diabetes, digestive disorders, and
some forms of cancer
• Vegetarians need to make sure their diets
provide the energy intake and food diversity
necessary to meet dietary guidelines
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Daily Values on Food
Labels
• FDA regulates food labels
– List serving size and number of servings
– Give total calories and calories from fat
• Look for foods with no more than 30 percent of their
calories from fat
– Show how much the food contributes to Daily
Values for important nutrients
– Shows % of Daily Value: recommended daily intake
of specified nutrients
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Nutrition Facts Food Label
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Front-of-Package Food
Labels
• FDA’s authority to regulate health claims on
front-of-package (FOP) food labels is limited
– Institute of Medicine found these labels provide
little guidance and cause confusion
• 12 different symbols, logos, and icons
– Recommended a standard for FOP labels
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Recommended FOP Labels
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Proposed Changes to the
Nutrition Facts Label
• 2014 proposed changes to Nutrition Facts
label for packaged food
– Mandated inclusion of information on added
sugars
– Updated reference amounts
– Specified calorie and nutrition information based
on whole package not just serving size
– Information on potassium and vitamin D in
packaged food required
– Altered label format to emphasize calories,
serving size, and Percent Daily value
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Restaurant Menu Labels
• 2010 Patient Protection and Affordable Care
Act includes new requirement: all chain
restaurants provide calorie labeling on their
menus
• Preliminary research suggests consumers
are no more likely to choose healthier menu
items
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Current Consumer
Concerns
• Overconsumption of soft drinks
• High-sodium diets
• Food allergies and food intolerances
– Eight foods responsible for 90% of allergies: milk,
eggs, peanuts, tree nuts, shellfish, soy, and wheat
– Food intolerances such as lactose intolerance are
less severe
• Gluten-free diets
– Celiac disease: immune reaction to gluten which
is found in wheat, barley, rye, and triticale
• Overconsumption of energy bars and
energy drinks
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Current Consumer
Concerns
• Probiotics, prebiotics, and synbiotics
– Probiotics are living bacteria that may aid
digestion; prebiotics are nondigestible
carbohydrates that fuel probiotics
– Synbiotics combine the two
– Scientific studies have not confirmed health
benefits
• Fast foods
• Food deserts: low-income areas where
more than 500 people or 33% have low
access to a supermarket
– When fresh produce not available, people don’t
have opportunity to choose a healthy diet
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Fast-Food Meal
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Organic Foods
• Plant foods grown without synthetic pesticides
or fertilizers
• Animal foods raised on organic feed without
antibiotics or growth hormone
• USDA regulates labeling
• Research has not demonstrated health
benefits, but environmental benefits are clear
– Look for foods that are not only organic but also
locally grown
– Wash organic produce thoroughly
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Foodborne Illnesses
• Food intoxication: food poisoning in which
food is contaminated by natural toxins
– Botulism
• Food infection: food poisoning in which food
is contaminated by disease-causing
microorganisms, or pathogens
– E. coli, salmonella, campylobacter
– Pet food can contain salmonella
• Use safe food practices and store food
safely, especially leftovers
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44
Kitchen Safety
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Genetically Modified Foods
• Genetically modified (GM) organisms:
genetic makeup has been changed to
produce desirable results
– Selective breeding
– Modern biotechnology faster and more refined
• Many crops are already GM
• Sixty percent of processed foods in
supermarkets contain one or more GM
ingredient
• Safety assessed by FDA’s Center for Food
Safety and Applied Nutrition (CFSAN)
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