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. Sources of Energy in the Diet

5. The Digestive System

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. Chemical Structure of Fats

13. Comparison of Dietary Fats

14. Total Fat Content of Foods

15. 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

16. Trans Fatty Acids

17. 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

18. 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

19. Saturated and Trans Fats: Comparing Butter and Margarine SOURCE: Food an Drug Administration

20. Total, Saturated, and Trans Fat Content of Selected Foods SOURCE: Food an Drug Administration

21. Fats and Health

22. 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

23. 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

24. 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

25. 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

26. 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.

27. 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

28. Glycemic Index

29. 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

30. 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

31. 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

32. 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

33. 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)

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

35. 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)

36. 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 B-6 • Vitamin E

37. 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

38. 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

39. 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

40. 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

41. 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

42. Antioxidants Donate Electrons and Stabilize Free Radicals

43. 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

44. 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 • Food Guide Pyramid = a food-group plan that provides practical advice to ensure a balanced intake of essential nutrients • Dietary Guidelines for Americans = general principles of good nutrition intended to help prevent certain diet-related diseases

45. 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

46. 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

47. 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

48. The USDA Food Guide Pyramid • Suggests a range of servings for five major food groups • Smaller number of servings are for those who consume about 1600 calories a day • Larger number of servings are for those who consume about 2800 calories a day • Keys are to choose a variety of foods within each group and to focus on nutrient density

49. The Food Guide Pyramid: A Guide to Daily Food Choices

50. Serving Sizes