Nutrition

1. Nutrition Chapter 8

2. Nutritional Requirements: Components of a Healthy Diet • Essential nutrients = substances the body must get from food because it cannot manufacture them at all or fast enough to meet its needs • Proteins • Carbohydrates • Fats • Vitamins • Minerals • Water

3. Energy from Food • Three classes of essential nutrients supply energy • 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”

4. 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

5. 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

6. Protein Sources • 3 ounces lean meat, poultry, or fish • 1/2 cup tofu • 20–25 grams of protein • 1 cup legumes • 15–20 grams of protein • 1 cup milk or yogurt or 1-1/2 ounces cheese • 8–12 grams of protein • Cereals, grains, nuts, vegetables • 2–4 grams of protein per serving

7. 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

8. 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

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

10. Types and Sources of Fats • Two key forms of polyunsaturated fats: • Omega-3 fatty acids are produced when 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 are produced when 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

11. 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

12. Trans Fatty Acids

13. 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

14. 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

15. 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

16. Carbohydrates—An Ideal Source of Energy • The primary function of dietary carbohydrate is to supply energy to body cells. • Some cells, such as those 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

17. 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

18. 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

19. 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 food label • Whole wheat, whole rye, whole oats, oatmeal, whole-grain corn, brown rice, popcorn, barley, etc. • Choose 3 or more servings of whole grains per day

20. Glycemic Index • Consumption of carbohydrates causes insulin and glucose levels in the blood to rise and fall • Glycemic index = 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

21. 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 • WHO: 10% or less of total daily calories • USDA: 8 teaspoons (32 grams) or less for a 2000-calorie diet

22. 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

23. 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

24. Types of Fiber • Soluble (viscous) fiber = fiber that dissolves in water or is broken down by bacteria in the large intestine • Slows the body’s absorption of glucose • Binds cholesterol-containing compounds • Insoluble fiber = fiber that doesn’t dissolve in water • Makes feces bulkier and softer • Helps prevent constipation, hemorrhoids, and diverticulitis

25. 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)

26. Recommended Intake of Fiber • Women = 25 grams per day • Men = 38 grams per day • Americans currently consume about half this amount

27. 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 (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)

28. 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 • Vitamins commonly lacking in the American diet: • Vitamin A • Vitamin C • Vitamin D • Vitamin E

29. 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

30. 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

31. 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) Osteoporosis—Thinning of Bones

32. Water—A Vital Component • Human body is composed of about 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 need to drink about 9 cups of fluid per day • Men need to drink about 13 cups of fluid per day • Drink in response to thirst; consume additional fluids for heavy exercise

33. 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

34. 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

35. 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 guidance system that provides practical advice to ensure a balanced intake of essential nutrients

36. 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

37. 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 D for older adults, people with dark skin, and people exposed to little sunlight • Vitamin K for newborns • People with certain special health concerns

38. 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

39. Dietary Guidelines for Americans • Consume a variety of nutrient-dense foods within and among the basic food groups, while staying within energy needs • Most Americans need to make the following general dietary changes: • 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

40. Dietary Guidelines for Americans • Control calorie intake to manage body weight • Evaluate body weight in terms of BMI • Make appropriate adjustments in calorie intake and activity levels • For most adults, a reduction of 50–100 calories per day can prevent gradual weight gain over time

41. Dietary Guidelines for Americans • Be physically active every day • To reduce the risk of chronic disease, 30 minutes per day of moderate activity • To prevent gradual weight gain, 60 minutes per day of moderate activity • To sustain weight loss, 60–90 minutes per day of moderate activity

42. Dietary Guidelines for Americans • Increase daily intake of foods from certain groups: • Fruits and vegetables, especially dark green vegetables, orange vegetables, and legumes • Whole grains—half of all daily grain servings (3 or more servings per day) • Fat-free or low-fat milk and milk products

43. Dietary Guidelines for Americans • Choose fats wisely for good health, limiting intake of saturated and trans fats • 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

44. Dietary Guidelines for Americans • Choose carbohydrates wisely for good health, limiting intake of added sugars • Cut back on soft drinks, candies, sweet desserts, fruit drinks, and other sweetened foods

45. Leading Sources of Calories in the American Diet 1. Regular soft drinks (7.1% of total calories) 2. Cake, sweet rolls, doughnuts, pastries (3.6%) 3. Hamburgers, cheeseburgers, meat loaf (3.1%) 4. Pizza (3.1%) 5. Potato chips, corn chips, popcorn (2.9%) 6. Rice (2.7%) 7. Rolls, buns, English muffins, bagels (2.7%) 8. Cheese or cheese spread (2.6%) 9. Beer (2.6%) 10. French fries, fried potatoes (2.2%) Source: Block, G. 2004. Foods contributing to energy intake in the U.S.: Data from NHANES III and NHANES 1999–2000. Journal of Food Composition and Analysis 17: 439–447.

46. Dietary Guidelines for Americans • Choose and prepare foods with little salt • 2300 mg daily limit • 1500 mg daily limit for older adults, African Americans, and people with hypertension • Consume potassium-rich foods • Leafy green vegetables, sweet and white potatoes, winter squash, soybeans, tomato sauce, bananas, peaches, apricots, cantaloupes, and orange juice

47. Dietary Guidelines for Americans • If you drink alcoholic beverages, do so in moderation, in situations that do not put yourself or others at risk • No more than 2 drinks per day for men • No more than 1 drink per day for women • Some groups should not drink at all

48. Dietary Guidelines for Americans • Keep foods safe to eat • To prevent foodborne illness, handle, cook, and store foods in ways that prevent microorganisms from spreading and multiplying

49. MyPyramid • Consume a balance of servings from each food group; the amount of food recommended from each food group is determined by total caloric intake • Engage in daily physical activity • Obtain a personalized plan by visiting www.MyPyramid.gov

50. MyPyramid: Grains • Half of daily servings should be whole grains • 6 ounce-equivalents daily for a 2000-calorie diet • 1 ounce-equivalents: • 1 slice of bread • 1 small (2-1/2-inch diameter) muffin • 1 cup ready-to-eat cereal flakes • 1/2 cup cooked cereal, rice, grains, or pasta • 1 6-inch tortilla