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Nutrition Basics

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You are what you eat!!!YOU ARE

WHAT YOU EAT!!!

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Nutrients

• Essential nutrients = substances the Essential nutrients = substances the body must get from food because it body must get from food because it cannot manufacture them at all or fast cannot manufacture them at all or fast enough to meet its needsenough to meet its needs: – Proteins– Carbohydrates– Fats– Vitamins– Minerals– Water

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Energy from Food• Kilocalorie = a measure of energy content in

food; the amount of heat it takes to raise the temperature of 1 liter of water 1°C; commonly referred to as “calorie”

• Three classes of essential nutrients supply energy– Fat = 9 calories per gram– Protein = 4 calories per gram– Carbohydrates = 4 calories per gram

*Although alcohol is NOT a nutrient it supplies seven calories per gram!

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Proteins—The Basis of Body Structure

• Protein = a compound made of amino acids that contains carbon, hydrogen, oxygen, and nitrogen

• Of twenty common amino acids in foods, nine are essential

• Proteins form key parts of the body’s main structural components—muscles and bones—and of blood, enzymes, cell membranes, and some hormones

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Complete and Incomplete Proteins

• Complete protein sources = foods that supply all the essential amino acids in adequate amounts– Meat, fish, poultry, eggs, milk, cheese, and soy

• Incomplete protein sources = foods that supply most but not all essential amino acids– Plants, including legumes, grains, and nuts

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Recommended Protein Intake

• Adequate daily intake of protein– 0.8 gram per kilogram

(0.36 gram per pound) of body weight

• Acceptable Macronutrient Distribution Range – 10–35% of total daily

calories as protein

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Fats - Essential in Small Amounts

• Fats – supply energy, insulate the body, support and

cushion organs, absorb fat-soluble vitamins, add flavor and texture to foods

• Essential fats – linoleic acid and alpha-linolenic acid are key

regulators of body process such as the maintenance of blood pressure and the progress of a healthy pregnancy

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Types and Sources of Fats

• Saturated fat = a fat with no carbon-carbon double bonds; usually solid at room temperature

– Found primarily in animal foods and palm and coconut oils

– Leading sources in our diets are: red meats, whole milk, cheese, hot dogs and lunch meats

• Monounsaturated fat = a fat with one carbon-carbon double bond; usually liquid at room temperature– Found in certain vegetables, nuts, and vegetable

oils (olive, canola, safflower, & peanut oils

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Types and Sources of Fats

• Polyunsaturated fat– a fat with two or more carbon-

carbon double bonds; usually liquid at room temperature

– Found in certain vegetables, nuts, and vegetable oils (soybean, corn, & cottonseed oils) and in fatty fish

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Types and Sources of Fats• Two key forms of polyunsaturated fats:

– Omega-3 fatty acids = the endmost double bond of a polyunsaturated fat occurs three carbons from the end of the fatty acid chain

• Found primarily in fish

– Omega-6 fatty acids = the endmost double bond of a polyunsaturated fat occurs six carbons from the end of the fatty acid chain

• Found primarily in certain vegetable oils, especially corn, soybean, and cottonseed oils

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Trans Fatty Acids• The process of hydrogenation, in

which hydrogens are added to unsaturated fats, – produces a mixture of saturated fatty

acids and standard and trans forms of unsaturated fatty acids

• Trans fatty acids have an atypical shape that affects their chemical activity

• Leading sources in our diet are– french fries, fried chicken, cakes,

cookies, pastries, doughnuts, chips, & stick margarine

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Fats and Health

• Fats affect blood cholesterol levels– Low-density lipoprotein (LDL) = “bad”

cholesterol– High-density lipoprotein (HDL) = “good”

cholesterol

• Saturated and trans fats raise levels of LDL; trans fats also lower levels of HDL

• Unsaturated fats lower levels of LDL

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Fats and Health

• Fats also affect triglyceride levels, inflammation, heart rhythm, blood pressure, and cancer risk

• Best choices– monounsaturated fats and

polyunsaturated omega-3 fats

• Limit intake of saturated and trans fats

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Saturated and Trans Fats: Comparing Butter and Margarine

0 5 10 15

Grams of fat in 1 tablespoon

Squeezemargarine

Tubmargarine

Margarinespread

Stickmargarine

Butter

Saturated fat

Trans fat

Other fats

SOURCE: Food an Drug Administration

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Total, Saturated, and Trans Fat Content of Selected Foods

0

5

10

15

20

25

30

To

tal f

at g

ram

s p

er s

ervi

ng

French fries Doughnut Pound cake Potato chips Candy bar Milk (whole)

Other fats

Trans fat

Saturated fat

SOURCE: Food an Drug Administration

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Recommended Fat Intake

• Adequate daily intake of fat:

= about 3–4 teaspoons of vegetable oil• Acceptable Macronutrient Distribution Range

= 20–35% of total daily calories as fat

Men Women

Linoleic acid 17 grams 12 grams

Alpha-linolenic acid 1.6 grams 1.1 grams

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Carbohydrates - An Ideal Source of Energy

• The primary function of dietary carbohydrate – to supply energy to body cells.

• Cells in the brain, nervous system, and blood,– use only carbohydrates for fuel

• During high-intensity exercise, – muscles get most of their energy from carbohydrates

• During digestion, – carbohydrates are broken into single sugar molecules

such as glucose for absorption; – the liver and muscles take up glucose and store it in

the form of glycogen

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Simple and Complex Carbohydrates

• Simple carbohydrates contain one or two sugar units in each molecule– Found naturally in fruits and milk and added to many

other foods– Include sucrose, fructose, maltose, and lactose

• Complex carbohydrates consist of chains of many sugar molecules– Found in plants, especially grains, legumes, and tubers– Include starches and most types of dietary fiber

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Whole Grains Before they are processed, all

grains are whole grains consisting of an inner layer of germ, a middle layer called the endosperm, and an outer layer of bran

During processing, the germ and bran are often removed, leaving just the starchy endosperm

Refined carbohydrates usually retain all the calories of a whole grain but lose many of the nutrients

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Refined Carbohydrates Versus Whole Grains

• Whole grains are higher than refined carbohydrates in fiber, vitamins, minerals, and other beneficial compounds

• Whole grains take longer to digest– Make people feel full sooner– Cause a slower rise in glucose levels

• Choose foods that have a whole grain as the first item on the ingredient list on the label– Whole wheat, whole rye, whole oats, oatmeal,

whole-grain corn, brown rice, popcorn, barley, etc.

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Glycemic Index• Consumption of carbohydrates

– causes insulin and glucose levels in the blood to rise and fall

• 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 changes in glucose levels

• Diets rich in high glycemic index foods – are linked to increased risk of diabetes and

heart disease

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Recommended Carbohydrate Intake• Adequate daily intake of carbohydrate

– 130 grams

• Acceptable Macronutrient Distribution Range – 45–65% of total daily calories as carbohydrate

• Limit on intake of added sugars– Food and Nutrition Board:

• 25% or less of total daily calories

– World Health Organization: • 10% or less of total daily calories

– MyPyramid: • 32 grams (8 tsp) in a 2000-calorie diet

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Acceptable Macronutrient Distribution Ranges: Summary

• Protein – 10–35% of total daily calories

• Fat – 20–35% of total daily calories

• Carbohydrate– 45–65% of total daily calories

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Fiber - A Closer Look• Dietary fiber

– nondigestible carbohydrates and lignin that are present naturally in plants

• Functional fiber– nondigestible carbohydrates isolated from natural

sources or synthesized in a lab and added to a food or supplement

• Total fiber– dietary fiber + functional fiber

• Fiber does not provide calories

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Types of Fiber• Soluble (viscous) fiber

– fiber that dissolves in water or is broken down by bacteria in the large intestine (oat bran, legumes)

– Slows the body’s absorption of glucose– Binds cholesterol-containing compounds

• Insoluble fiber – fiber that doesn’t dissolve in water (wheat bran, psyllium

seed)– Makes feces bulkier and softer– Helps prevent constipation, hemorrhoids, and

diverticulitis

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Sources of Fiber

• All plant foods contain fiber, but processing can remove it

• Good sources of fiber:– Fruits (especially whole, unpeeled fruits)– Vegetables– Legumes– Oats (especially oat bran)– Whole grains and wheat bran– Psyllium (found in some cereals and laxatives)

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Recommended Intake of Fiber

• Women – 25 grams per day

• Men – 38 grams per day

• Americans currently consume – about half this amount

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Vitamins—Organic Micronutrients

• Vitamins – organic (carbon-containing) substances needed

in small amounts to help promote and regulate chemical reactions and processes in body cells.

• Four vitamins are fat-soluble – Vitamin A, D, E, and K

• Nine vitamins are water-soluble – C and the eight B-complex vitamins: thiamin,

riboflavin, niacin, vitamin B-6, folate, vitamin B-12, biotin, and pantothenic acid

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Vitamins• Vitamins are abundant in fruits,

vegetables, and grains; they are also added to some processed foods

• If you consume too much or too little of a particular vitamin, characteristic symptoms of excess or deficiency can develop

• It is best to obtain most of your vitamins from foods rather than supplements

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Minerals- Inorganic Micronutrients

• Minerals = 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 include copper, fluoride, iodide, iron, selenium, and zinc

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Minerals• If you consume too much or too little of a

particular mineral, characteristic symptoms of excess or deficiency can develop

• Minerals commonly lacking in the American diet:– Iron = low intake can cause anemia

– Calcium = low intake linked to osteoporosis

– Potassium = low intake linked to elevated blood pressure and bone mineral loss

– Magnesium

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Osteoporosis - Thinning of Bones

• Dietary factors that build bone mass:– Calcium– Vitamin D– Vitamin K– Other possible dietary factors:

vitamin C, magnesium, potassium, manganese, zinc, copper, boron

• Weight-bearing exercise and strength training also build and maintain bone mass

• Dietary factors linked to loss of bone mass:– Alcohol– Sodium– Caffeine– Retinol– Soda– Protein (if intake of calcium

and vitamin D is low)

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Water - A Vital Component• Human body is composed of about 50–60%

water;– you can live only a few days without water

• Foods and fluids you consume provide 80–90% of your daily water intake

• Adequate intake to maintain hydration:– Women = about 9 cups of fluid per day– Men = about 13 cups of fluid per day

• Drink in response to thirst; – consume additional fluids for heavy exercise

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Other Substances in Food: Antioxidants

• Antioxidant – a substance 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 radical - a chemically unstable, electron-seeking compound

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

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Other Substances in Food: Phytochemicals

• Phytochemical – a naturally occurring substance found in plant foods that

may help prevent and treat chronic diseases

• Examples:– Certain proteins in soy foods– Sulforaphane in cruciferous vegetables (cabbage,

broccoli, brussels sprouts, kale, cauliflower)– Allyl sulfides in garlic and onions

• Fruits and vegetables are rich in phytochemicals

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Nutritional Guidelines: Planning Your Diet

• Dietary Reference Intakes (DRIs)– standards for levels of nutrient intake to prevent nutrient

deficiencies and reduce the risk of chronic disease

• Dietary Guidelines for Americans – general principles of good nutrition intended to help

prevent certain diet-related diseases

• MyPyramid – a food-group plan that provides practical advice to

ensure a balanced intake of essential nutrients

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Dietary Reference Intakes (DRIs)

• Set by the Food and Nutrition Board of the National Academies

• Recommended Dietary Allowance (RDA) or Adequate Intake (AI) = recommended intake

• Tolerable Upper Intake Level (UL) – maximum daily intake unlikely to cause health

problems• Example of calcium recommendations for an

18-year-old woman: – RDA = 1300 mg/day– UL = 2500 mg/day

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Should You Take Supplements?• The Food and Nutrition Board recommends

supplements only for certain groups:– Folic acid for women capable of becoming

pregnant (400 µg/day)– Vitamin B-12 for people over age 50 (2.4

mg/day)• Other possible situations for supplements:

– Vitamin C for smokers– Iron for menstruating women– Vitamin K for newborns– People with certain special health concerns

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Daily Values

• Daily Values – a simplified version of the RDAs used on

food labels

• Also included in Daily Values are standards for nutrients with no established RDA

• Shown on food labels in terms of a 2000-calorie diet

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Dietary Guidelines for Americans

• Adequate Nutrients within Calorie Needs– Focus on nutrient dense foods.– Eat more dark green vegetables, orange

vegetables, legumes, fruits, whole grains, and low-fat and fat-free milk and milk products.

– Eat less refined grains, saturated fat, trans fat, cholesterol, added sugars, and calories.

– Plans that meet the goals include MyPyramid and DASH.

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Dietary Guidelines for Americans

• Weight Management– Evaluate body weight in

terms of BMI.

– Balance food intake and physical activity to avoid weight gain.

– To lose weight, decrease calorie intake, maintain adequate nutrient intake, and increase physical activity.

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Dietary Guidelines for Americans

• Physical Activity– 30 minutes per day to reduce

risk of chronic disease– 60 minutes per day to prevent

weight gain– 60-90 minutes per day to

sustain weight loss

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Dietary Guidelines for Americans

• Food Groups to Encourage– Fruits and vegetables—

choose a variety of colors and kinds

– Whole grains—half of all servings of grains should be whole grains

– Low-fat and fat-free milk and milk products

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Dietary Guidelines for Americans

• Fat Intake Goals

– Total fat: 20-35% of total daily calories

– Saturated fat: Less than 10% of total daily calories

– Trans fat: As little as possible

– Cholesterol: Less than 300 mg per day

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Dietary Guidelines for Americans

• Carbohydrate Intake– Choose high-fiber foods– Limit intake of added sugars

• Sodium and Potassium– Limit sodium intake

• 2300 mg per day; 1500 mg per day for those at high risk

– Consume adequate potassium

• Alcohol intake—moderate if at all

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MyPyramid

• Food guidance system that promotes healthy food choices and physical activity

• Choosing a balance of servings from different food groups meets nutrient needs and reduces chronic disease risk

• Balancing food choices and activity promotes weight management

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MyPyramid

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MyPyramid: Grains

• For a 2000-calorie diet– choose 6 ounce-equivalents per day

• 1 ounce-equivalent:– 1 slice of bread– 1 small muffin– 1 cup ready-to-eat cereal flakes– 1/2 cup cooked cereal, rice, grains,

pasta– 1 6-inch tortilla

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MyPyramid: Vegetables

• For a 2000-calorie diet, – choose 2-1/2 cups (5

servings) per day

• 1/2 cup or equivalent:– 1/2 cup raw or cooked

vegetables– 1/2 cup vegetable juice– 1 cup raw leafy salad

greens

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MyPyramid: Vegetables• Choose vegetables from five groups:

– Dark green vegetables • spinach, kale, collards, bok choy, other leafy

greens

– Orange and deep yellow vegetables • carrots, winter squash, sweet potatoes

– Legumes – Starchy vegetables

• corn, potatoes, peas

– Others (e.g., tomatoes, bell peppers, green beans, cruciferous vegetables)

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MyPyramid: Fruits• For a 2000-calorie diet,

choose 2 cups (4 servings) per day

• 1/2 cup or equivalent:– 1/2 cup fresh, canned, or frozen

fruit– 1/2 cup fruit juice (100% juice)– 1 small whole fruit– 1/4 cup dried fruit

• Choose whole fruits often

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MyPyramid: Milk

• For a 2000-calorie diet, choose 3 cups or the equivalent per day

• 1 cup or equivalent:– 1 cup milk or yogurt– 1/2 cup ricotta cheese– 1-1/2 ounces natural cheese– 2 ounces processed cheese

• Choose low-fat and fat-free items

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MyPyramid: Meat and Beans

• For a 2000-calorie diet, choose 5-1/2 ounce-equivalents per day

• 1-ounce equivalents:– 1 ounce cooked lean meat, poultry, fish– 1/4 cup tofu or cooked legumes– 1 egg– 1 tablespoon peanut butter– 1/2 ounce nuts or seeds

• Choose lean cuts, limit serving sizes, and try one plant protein source daily

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MyPyramid: Oils

• For a 2000-calorie diet, choose 6 teaspoons per day

• 1 teaspoon or equivalent:– 1 teaspoon vegetable oil or soft margarine– 1 tablespoon salad dressing or light

mayonnaise– Food sources: 8 large olives, 1/6 medium

avocado, 1/2 tablespoon peanut butter, 1/3 ounce roasted nuts

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The Vegetarian Alternative• Types of vegetarian diets

– 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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Vegetarian Diets and Health

• Vegetarian diets – are lower in saturated fat and cholesterol– higher in complex carbohydrates, fiber,

folate, vitamins C and E, carotenoids, and phytochemicals

• Nutrients of concern for vegetarians– vitamin B-12, vitamin D, calcium, iron, and

zinc

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Dietary Challenges for Special Population Groups

• Women– nutrient density, calcium, iron

• Men– fruits, vegetables, grains

• College students– overall quality of food choices

• Older adults– nutrient density, fiber, vitamin B-12

• People with special health concerns– discuss with physician or dietitian

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Food Labels

Read labels to learn more about your food choices.

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Dietary Supplements• May contain powerful

bioactive chemicals

• Not regulated the way drugs are by the FDA in terms of testing and manufacture

• May interact with prescription and over-the-counter drugs and supplements

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Foodborne Illness• Most caused by pathogens (disease-causing

microorganisms)• You can’t tell by taste, smell, or sight whether

a food is contaminated• To prevent foodborne illness

– handle, cook, and store foods in ways that prevent microorganisms from spreading and multiplying

• New threat– bovine spongiform encephalopathy (BSE or “mad

cow disease”)

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FoodSafety

• Cook foods to an appropriate temperate

• Keep hot foods hot and cold foods cold

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Organic Foods

• Organic• a designation applied to foods grown and

produced according to strict guidelines limiting the use of pesticides, nonorganic ingredients, hormones, antibiotics, genetic engineering, irradiation, and other practices

• Organic foods tend to have lower levels of pesticide residues than conventionally grown crops

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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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Genetically Modified Foods

• GM organism– a plant, animal, or microorganism in which

genes have been added, rearranged, or replaced through genetic engineering

• Many GM crops are already grown in the United States – soybeans, corn

• No labeling requirement unless a GM food contains a known allergen

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Food Allergies

• Reaction by the immune system to a food or food ingredient

• Common food allergens – peanuts, milk, eggs, tree nuts, soy,

wheat, fish, and shellfish

• Severe allergic responses can include anaphylaxis

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Food Intolerance

• More common than true food allergies• Reaction to a food or food ingredient,

– usually based on a problem with metabolism

• Common intolerances include lactose intolerance, – in which people are deficient in the enzyme lactase,

and gluten intolerance

• Problems can be avoided – by avoiding or limiting trigger foods

• Keep a food diary to help identify problems

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A Personal Plan: Applying Nutritional Principles

• Assess your current diet

• Set reasonable goals for change

• Try additions and substitutions to bring your current diet closer to your goals

• Adjust one meal or eating habit at a time

• Plan ahead for challenging situations

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Web Site Resources

• American Dietetic Association: www.eatright.org

• American Heart Association: www.deliciousdecisions.org

• FDA Center for Food Safety & Applied Nutrition: http://vm.dfsan.fda.gov

• Gateways to Government Nutrition Information: www.foodsafety.gov www.nutrition.gov

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Web Site Resources, con’t.

• Harvard School of Public Health Nutrition Source: www.hsph.harvard.edu/nutritionsource

• Choose My Plate: http://www.choosemyplate.gov/

• National Cancer Institute:http://5aday.nci.nih.gov

• Tufts University Nutrition Navigator: http://navigator.tufts.edu

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Web Site Resources, con’t.

• Pepsico: www.smartspot.com

• Fast Food Facts: www.foodfacts.info

• My Fitness Pal: www.myfitnesspal.com

• Self Nutrition Data: http://nutritiondata.self.com/tools/calories-burned