1. Copyright © 2003 Delmar Learning, a Thomson Learning company Section 1 Fundamentals of Nutrition

2. Copyright © 2003 Delmar Learning, a Thomson Learning company Chapter 5 Lipids, or Fats

3. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company3 Objectives  State the functions of fats in the body  Identify sources of dietary fats  Explain common classifications of fats  Describe disease conditions with which excessive use of fats is associated

4. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company4 Facts Fats belong to a group of organic compounds called lipids. Greasy substances that are insoluble in water. Each gram of fat contains 9 kcal. Composed of carbon, hydrogen, and oxygen; lower proportion of oxygen than carbohydrates.

5. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company5 Functions Provide energy Carry fat-soluble vitamins Supply essential fatty acids Protect and support organs and bones Insulate from cold Provide satiety to meals

6. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company6 Food Sources Animal Fatty meats Lard Butter Cheese Cream; whole milk Egg yolk Plant Vegetable oils Nuts Chocolate Avocados Olives Margarine

7. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company7 Visible and Invisible Fats Visible fats Fats in foods that are purchased and used as fats, such as butter or margarine, lard, cooking oils Invisible fats Fats that are not immediately noticeable such as those in egg yolk, cheese, cream, and salad dressings

8. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company8 You are the nurse teaching a class about nutrition. A client asks about ways to decrease the amount of fat in the diet. What are some suggestions you can give?

9. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company9 Beware of hidden fats! Decrease the amount of fatty meats (bacon, sausage, luncheon meats) and use lean meats instead. Use low-fat or skim milk. Use egg whites instead of yolks when possible. (Egg white contains no fat; it is almost entirely protein and water.)

10. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company10 Classification Triglycerides Most lipids in the body (95%) are triglycerides Composed of three fatty acids attached to a framework of glycerol Phospholipids Sterols Cholesterol

11. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company11 Fatty Acids Fatty acids are organic compounds of carbon atoms to which hydrogen atoms are attached. They may be classified in two ways.

12. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company12 Fatty Acid Classification May be classified by the body’s need for them Essential Nonessential May be classified by degree of saturation with hydrogen atoms Saturated Unsaturated - Monounsaturated - Polyunsaturated

13. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company13 Essential Fatty Acids Cannot be synthesized by the body Must be obtained from the diet Types Linoleic acid Linolenic acid

14. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company14 Non-essential Fatty Acids Can be synthesized by the body Arachidonic fatty acid, previously thought to be essential, can be synthesized in the body from linoleic fatty acid.

15. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company15 Saturated Fats Each of its carbon atoms carries all the hydrogen atoms possible. In general, animal foods contain more saturated fatty acids than unsaturated. Usually solid at room temperature. Examples: Meat, poultry, egg yolks, whole milk, whole milk cheeses, cream, ice cream, butter, chocolate, coconut, palm oil

16. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company16 Monounsaturated Fats Fewer hydrogen atoms attached to one place among the carbon atoms of its fatty acids than saturated fats. Lowers low-density lipoprotein (LDL or “bad cholesterol”). Examples: Olive oil, canola oil, avocados, cashew nuts Recommended: 15% of total daily kcal

17. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company17 Polyunsaturated Fats Fewer hydrogen atoms attached to two or more places among the carbon atoms of its fatty acids than saturated fats. Examples: Cooking oils made from sunflower, safflower, sesame seeds or from corn or soybeans, soft margarines whose major ingredient is liquid vegetable oil, and fish

18. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company18 Polyunsaturated Fats Foods containing high proportions of polyunsaturated fats are usually soft or oily. Omega-3 fatty acids (found in fish) lower the risk of heart disease. Omega-6 (linoleic acid) has a cholesterol- lowering effect. Recommended: 10% of total daily kcal

19. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company19 Hydrogenated Fats Polyunsaturated vegetable oils to which hydrogen has been added commercially to make them solid at room temperature. This process, called hydrogenation, turns polyunsaturated vegetable oils into saturated fats. Margarine is made in this way.

20. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company20 Trans-Fatty Acids (TFAs) Produced when hydrogen atoms are added to monounsaturated or polyunsaturated fats to produce a semi-solid product like margarine and shortening. TFAs raise low-density lipoproteins (LDL) and total cholesterol. Major source: baked goods and restaurant foods

21. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company21 Phospholipid Found in both plant and animal foods, and is synthesized in the liver. Natural emulsifier that helps transport fat in the bloodstream. Example: Lecithin

22. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company22 Cholesterol Cholesterol is a sterol Fatlike substance Exists in animal foods and body cells Does not exist in plant foods Essential for the synthesis of bile, sex hormones, cortisone, and vitamin D Needed by every cell in the body

23. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company23 Your client has been diagnosed with a high cholesterol level greater than 200 mg/dl. Answer the following questions: What risks are associated with a high cholesterol level? What can be done to lower a high cholesterol level?

24. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company24 High cholesterol leads to atherosclerosis, a cardiovascular disease in which plaque (fatty deposits containing cholesterol and other substances) forms on the inside of artery walls. This can lead to heart attacks and strokes.

25. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company25 Reduce the amount of total fat, saturated fats, and cholesterol. Increase monounsaturated fats in the diet, lose weight and exercise. Increase consumption of soluble dietary fiber. Medication may be prescribed in some cases. Daily cholesterol intake should not exceed 300 mg.

26. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company26 Digestion and Absorption 95% of ingested fats are digested Complex process Chemical digestion of fats occurs mainly in the small intestine No digestion of fats occurs in the mouth Slight digestion in stomach where gastric lipase acts on emulsified fats such as those found in cream and egg yolk.

27. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company27 Digestion and Absorption Digestion in the small intestine Bile emulsifies the fats The enzyme pancreatic lipase reduces the fats to fatty acids and glycerol The body subsequently absorbs through the villi of the small intestine

28. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company28 Digestion and Absorption

29. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company29 Lipoproteins In the initial stages of fat absorption, bile joins with the products of fat digestion to carry fat. Later, protein combines with the final products of fat digestion to form special carriers called lipoproteins. Lipoproteins carry the fat in the blood to the body cells.

30. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company30 Lipoproteins Classified according to mobility and density Types Chylomicrons Very-low-density lipoproteins (VLDLs) Low-density lipoproteins (LDLs) High-density lipoproteins (HDLs)

31. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company31 Chylomicron First lipoprotein identified after eating Largest lipoprotein Lightest in weight Composed of 80-90% triglycerides

32. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company32 Very-low-density Lipoproteins (VLDLs) Made by the liver to transport lipids throughout the body. Composed of 55-65% triglycerides. Carry triglycerides and other lipids to all cells. As the VLDL lose triglycerides, they pick up cholesterol from other lipoproteins in the blood and they then become LDL.

33. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company33 Low-density Lipoproteins (LDLs) Composed of 45% cholesterol with few triglycerides. Carry most of the blood cholesterol from the liver to the cells. Elevated blood levels greater than 130 mg/dl of LDL are thought to be contributing factors in atherosclerosis. “Bad cholesterol”

34. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company34 High-density Lipoproteins (HDLs) Carry cholesterol from the cells to the liver for eventual excretion. Levels of HDL greater than 35 mg/dl are thought to reduce the risk of heart disease. Exercise, maintaining a desirable weight, and giving up smoking are all ways to increase one’s HDL. “Good cholesterol”

35. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company35 Metabolism and Elimination The liver controls fat metabolism. The metabolism of fats occurs in the cells. Fatty acids are broken down to carbon dioxide and water, releasing energy. Portion of fat not needed for immediate use stored as adipose tissue. Carbon dioxide and water are waste products removed from the body by the circulatory, respiratory, and excretory systems.

36. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company36 Your client asks you about a new dietary supplement that advertisers claim provides essential nutrients and lowers cholesterol “naturally”. How do you advise your client?

37. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company37 Any new dietary “supplement” for which a nutrition claim is made should be carefully evaluated. If the item is not included in the RDA or DRI, it is safe to assume that medical research has not determined that it is essential. Ingestion of dietary supplements of unknown value could, ironically, be damaging to one’s health.

38. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company38 Fat Alternatives Olestra: Made from carbohydrates and fat FDA approved for use in snack food Government requires that food labels indicate olestra “inhibits absorption of some vitamins and other nutrients” Contains no calories; can cause cramps and diarrhea Simplesse: Made from egg white or milk protein Oatrim: Carbohydrate-based; derived from oat fiber

39. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company39 Dietary Requirements The Food and Nutrition Board’s Committee on Diet and Health recommends that people reduce their fat intake to 30% of total kcal. American Heart Association’s newest recommendation is to consume </=7% of saturated fats, 8-10% polyunsaturated fats and 15% monounsaturated fats. At present, 36% of kcal in U.S. diets is derived from fats.

40. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company40 Conclusion Fats provide energy, carry essential fatty acids and fat-soluble vitamins, protect organs and bones, insulate from cold, and provide satiety to meals. Composed of carbon, hydrogen, and oxygen and are found in both animal and plant foods.

41. Chapter 5Copyright © 2003 Delmar Learning, a Thomson Learning company41 Conclusion Each gram of fats provides 9 kcal. Digestion occurs primarily in small intestines. An excess of fat in the diet can result in obesity and possible heart disease or cancer.