Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Chapter 5 Lipids, or Fats

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Objectives State functions of fats in body Identify sources of dietary fats Explain common classifications of fats Describe disease conditions with which excessive use of fats are associated

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Facts Fats –Belong to group of organic compounds Lipids –Greasy substances –Insoluble in water Each gram of fat contains 9 calories Composed of carbon, hydrogen, and oxygen –Lower proportion of oxygen than carbohydrates

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Functions Provide energy Carry fat-soluble vitamins Supply essential fatty acids Protect and support organs and bones Insulate from cold Provide satiety after meals

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Food Sources Animal –Fatty meats and fish –Dairy products –Egg yolks (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Food Sources Plant –Cooking oils and margarine –Nuts –Avocados –Coconut –Cocoa butter

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Visible and Invisible Fats Visible –Fats in foods that are purchased and used as fats –E.g., butter, margarine, lard, cooking oils Invisible –Fats not immediately noticeable –E.g., egg yolks, cheese, cream, salad dressings

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Consider the following scenario: –You are the nurse teaching a class about nutrition. A client asks about ways to decrease the amount of fat in his diet. What are some suggestions you can offer him? (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Beware of hidden fats Decrease amount of fatty meats –E.g., bacon, sausage, luncheon meats –Use lean meats, instead Use low-fat or skim milk Use egg whites instead of yolks when possible –Egg white contains no fat Almost entirely protein and water

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Classification Triglycerides –Most lipids in body 95 percent –Composed of three fatty acids attached to framework of glycerol Phospholipids Sterols –Cholesterol

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Fatty Acid Classification May be classified by body’s need for them: –Essential fatty acids (EFAs) –Nonessential (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Fatty Acid Classification May be classified by degree of saturation with hydrogen atoms: –Saturated –Unsaturated Monounsaturated Polyunsaturated

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Essential Fatty Acids Cannot be synthesized by body Must be obtained from diet Two families: –Omega-3 –Omega-6

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Nonessential Fatty Acids Can be synthesized by body Omega-9 fatty acids can be synthesized in body when EFAs present –Previously thought to be essential

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Saturated Fats Each of its carbon atoms carries all hydrogen atoms possible In general, animal foods contain more saturated fatty acids than unsaturated Usually solid at room temperature (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Saturated Fats E.g., meat, poultry, egg yolks, whole milk, whole milk cheeses, cream, ice cream, butter, chocolate, coconut, palm oil

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Monounsaturated Fats Have one place among carbon atoms where there are fewer hydrogen atoms attached than in saturated fats Lower low-density lipoprotein (LDL or “bad” cholesterol) when they replace saturated fat in one’s diet (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Monounsaturated Fats E.g., olive oil, canola oil, avocados, cashew nuts Recommend 15 percent of total daily calories

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Polyunsaturated Fats Have two or more places among carbon atoms where there are fewer hydrogen atoms attached than in saturated fats E.g., cooking oils made from sunflower, safflower, sesame seeds, corn, or soybeans; soft margarines with liquid vegetable oil as major ingredient; fish (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Polyunsaturated Fats Foods containing high proportions of polyunsaturated fats –Usually soft or oily Omega-3 –Lower risk of heart disease (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Polyunsaturated Fats Omega-6 –Lower cholesterol Recommend 8 percent or less of total daily calories

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Trans Fatty Acids (TFAs) Produced when hydrogen atoms added to monounsaturated or polyunsaturated fats to produce semi-solid product –E.g., margarine, shortening Raise LDL and total cholesterol (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. TFAs Major sources: –Baked goods –Restaurant foods

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Hydrogenated Fats Polyunsaturated vegetable oils to which hydrogen has been added commercially to make them solid at room temperature Hydrogenation –Process that turns polyunsaturated vegetable oils into saturated fats –E.g., margarine, shortening

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Cholesterol Sterol –Fatlike substance Exists in animal foods and body cells Does not exist in plant foods (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Cholesterol Essential for synthesis of bile, sex hormones, cortisone, and vitamin D Needed by every cell in body, but manufactured by liver

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Consider the following scenario: –Your client has been diagnosed with a high cholesterol level greater than 200 mg per dL. Answer the following questions: What risks are associated with a high cholesterol level? What can be done to lower a high cholesterol level? (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share High cholesterol leads to atherosclerosis –Cardiovascular disease in which plaque forms on inside of artery walls Plaque –Fatty deposits containing cholesterol and other substances –Can lead to heart attacks and strokes (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Reduce amount of total fat, saturated fats, and cholesterol Increase monounsaturated fats, lose weight, and exercise Increase consumption of soluble dietary fiber (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Do not exceed daily cholesterol intake of 300 mg In some cases, have medication prescribed

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Digestion and Absorption 95 percent of ingested fats digested Chemical digestion of fats occurs mainly in small intestine No digestion of fats occurs in mouth Slight digestion in stomach where gastric lipase acts on emulsified fats (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Digestion and Absorption Digestion in small intestine –Bile emulsifies fats –Lipase reduces fats to fatty acids and glycerol –Absorption occurs through villi of small intestine

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Lipoproteins Bile joins with products of fat digestion to carry fat Protein combines with final products of fat digestion to form lipoproteins Lipoproteins carry fat in blood to body cells (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Lipoproteins Classified according to mobility and density Types: –Chylomicrons –Very-low-density lipoproteins (VLDLs) –LDLs –High-density lipoproteins (HDLs)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Chylomicron First lipoprotein identified after eating Largest lipoprotein –Yet lightest in weight Composed of 80 to 90 percent triglycerides

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. VLDLs Made by liver to transport lipids throughout body Composed of 55 to 65 percent triglycerides Carry triglycerides and other lipids to all cells As VLDL lose triglycerides, pick up cholesterol from other lipoproteins in blood –Become LDL

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. LDLs Composed of 45 percent cholesterol with few triglycerides Carry most of blood cholesterol from liver to cells Level greater than 130 mg per dL –Considered to contribute to atherosclerosis “Bad” cholesterol

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. HDLs Carry cholesterol from cells to liver for eventual excretion Level of 60 mg per dL or more –Considered to reduce risk of heart disease (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. HDLs Increase by doing the following: –Exercising –Maintaining desirable weight –Giving up smoking “Good” cholesterol

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Metabolism and Elimination Liver controls fat metabolism In cells, fatty acids broken down to carbon dioxide and water –Releasing energy (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Metabolism and Elimination Excess fat stored as adipose tissue Carbon dioxide and water removed from body by circulatory, respiratory, and excretory systems

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Consider the following scenario: –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? (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Stop and Share Any new dietary supplement with nutritional claim should be evaluated carefully If item not included in Recommended Daily Allowance (RDA) or DRI, assume medical research has not determined it essential Ingestion of dietary supplements of unknown value could be damaging to one’s health

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Phospholipid Found in both plant and animal foods Synthesized in liver Natural emulsifier that helps transport fat in bloodstream E.g., lecithin

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Fat Alternatives Olestra –Made from carbohydrates and fat –FDA approved for use in snack food –Food labels must indicate that it “inhibits absorption of some vitamins and other nutrients” –Should be used in moderation –Contains no calories –Can cause cramps and diarrhea (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Fat Alternatives Simplesse –Made from egg white or milk protein –Can be used only in cold foods –Not available for home use (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Fat Alternatives Oatrim –Carbohydrate-based Derived from oat fiber –Can be used in baking But not frying –Provides calories But less than fat

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Dietary Requirements Deficiency symptoms occur when fats provide less than 10 percent of total daily calories Food and Nutrition Board’s Committee on Diet and Health recommends that people reduce fat intake to 30 percent of total calories (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Dietary Requirements American Heart Association’s newest recommendation: –Consume ≤ 7 percent of saturated fats, 8 percent polyunsaturated fats, and 15 percent monounsaturated fats At present, 36 percent of calories in U.S. diets derived from fats

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Conclusion Fats provide energy, carry essential fatty acids and fat-soluble vitamins, protect organs and bones, insulate from cold, and provide satiety after meals Fats are composed of carbon, hydrogen, and oxygen –Found in both animal and plant foods (continues)

Copyright © 2011 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Conclusion Each gram of fat provides 9 calories Digestion occurs primarily in small intestines Excess of fat in diet can result in obesity, heart disease, or cancer