Chapter 5 Lipids Or Fats PDF

5 Lipids, or Fats  Facts Fats belong to a group of organic compounds called lipids(fatty/waxy compounds) Greasy substances that are insoluble(impossible to solve) in water Each gram of fat contains 9 calories....

5 Lipids, or Fats  Facts Fats belong to a group of organic compounds called lipids(fatty/waxy compounds) Greasy substances that are insoluble(impossible to solve) in water Each gram of fat contains 9 calories. Composed of carbon, hydrogen, and oxygen; lower proportion of oxygen than carbohydrates. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Functions Provide energy Carry fat-soluble vitamins Supply essential fatty acids Protect and support organs and bones Insulate(isolate)from cold Provide satiety(fullness) after meals 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Food Sources Animal Fatty meats and fish Dairy products (condensed and dried milk,yogurt ,cheese &ice cream Whole milk (cow’s milk and skim milk –Nido milk) Egg yolk 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Food Sources Plant Vegetable oils and margarine Nuts and olives Chocolate Avocados 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Visible and Invisible Fats Visible fats Invisible fats Fats in foods that Fats that are not are purchased immediately and used as fats, noticeable such such as butter or as those in egg margarine, lard, yolk, cheese, cooking oils cream, and salad dressings 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Classification Triglycerides(type of fat called lipid circulated in blood common in butter and oil) Most lipids in the body (95%) are triglycerides. Composed of three fatty acids attached to a framework of glycerol Phospholipids(common in alcohol &fatty acids) Sterols (steroids alcohol typically waxy.Example : sesame oil , mayonnaise) Cholesterol 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Fatty Acid Classification May be classified by the body’s need for them: Essential fatty acids (EFAs) Nonessential 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Fatty Acid Classification May be classified by degree of saturation with hydrogen atoms: Saturated (butter ,meats and dairy) Unsaturated(vegetable and olive oils) Monounsaturated (healthy fat) Polyunsaturated (dietary fat) 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Essential Fatty Acids Cannot be synthesized by the body and must be obtained from the diet Two families: 1. Omega-3 (found in sea foods) 2. Omega-6 (found in nut and seed) 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Nonessential Fatty Acids Can be synthesized by the body Omega-9 fatty acids(Ex:sunflower/macadamia nuts olive oil and soybean,) previously thought to be essential, can be synthesized in the body when Essential Fatty Acids are present. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Saturated Fats Each (type ofcontaining of fats its carbon atomsof fatty high proportion carries allmolecules) acid and 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 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Monounsaturated Fats (dietary fat that help reduce LDL (bad cholesterol)in the blood) Have one place among the carbon atoms where there are fewer hydrogen atoms attached then in saturated fats. Lower low-density lipoprotein (LDL or “bad” cholesterol) when they replace saturated fat in one’s diet “Bad Cholesterol or high level of cholesterol may rise your risk of heart disease and stroke. Examples: olive oil, canola oil, avocados, cashew nuts Recommended: 15% of total daily calories 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Polyunsaturated Fats (type of fats that are typically liquid at room temperature and turned solid when chilled) Have two or more places among the carbon atoms where there are fewer hydrogen atoms attached then in 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 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Polyunsaturated Fats Ex: fatty oily fish such as anchovies ,mackerel, tuna etc.) 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 fatty acids have a cholesterol- lowering effect. Recommended: 8% or less of total daily calories 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Trans-Fatty Acids (TFAs) (made of liquid oil turned into solid fats like shortening or margarine) Produced when hydrogen atoms are added to monounsaturated or polyunsaturated fats to produce a semi- solid product such as margarine or shortening TFAs raise low-density lipoproteins (LDL) and total cholesterol. Major source: baked goods (foods made from dough )and restaurant foods(all foods,meals and drinks) 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Hydrogenated Fats oil where chemical structure change to become solid fats (become solid foods in room temperature) 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 and shortening are made in this way. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Cholesterol isCholesterol a sterol, a fatlike substance. (waxy fat like substance of the body needs for good health but in the Exists in animal right foods and body cells amount.) Normal Values :less than 200 mg/dl 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 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Digestion and Absorption 95% of ingested fats are digested through a 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 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Digestion and Absorption Digestion in the small intestine Bile emulsifies the fats. The enzyme pancreatic lipase reduces the fats to fatty acids and glycerol(colorless viscous liquid formed) The body subsequently absorbs through the villi of the small intestine. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Lipoproteins (protein mixture of fats and protein that transport cholesterol in the blood to cell through out the body) 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.(lipids in blood plasma) Lipoproteins carry the fat in the blood to the body cells. 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Lipoproteins Classified according to mobility and density Types Chylomicrons(droplet of fat in the blood) Very-low-density lipoproteins (VLDLs) Low-density lipoproteins (LDLs) High-density lipoproteins (HDLs) 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Chylomicron Ex.fatty acid and cholesterol First lipoprotein identified after eating Largest lipoprotein(group of soluble protein) Lightest in weight Composed of 80%–90% triglycerides 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  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. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  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 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  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(absorbs cholesterol in the blood &carries it back to liver and flushes it from the body) 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Metabolism and Elimination The liver controls fat metabolism, which occurs in the cells. Fatty acids are broken down to carbon dioxide and water, releasing energy. Fat not needed for immediate use is stored as adipose tissue. Carbon dioxide and water are waste products removed from the body by the circulatory, respiratory, and excretory systems. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Phospholipid Found in both plant and animal foods, and is synthesized (combination)in the liver Natural emulsifier that helps transport fat in the bloodstream Example: lecithin (distributed in animal tissue and egg yolk 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  Fat Alternatives Olestra -synthetic cooking oil used in calorie free fat substitute in various foods 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” Should be used in moderation Contains no calories; can cause cramps and diarrhea 5-0 (continues) Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Fat Alternatives Simplesse (common found in ice cream,yogurt and salad dressings) Made from egg white or milk protein Can be used only in cold foods Oatrim(fat-replacer:gelatin) Carbohydrate-based; derived from oat fiber Can be used in baking but not frying 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.  (continued) Conclusion Each gram of fats provides 9 calories. Digestion occurs primarily in small intestines. An excess of fat in the diet can result in obesity and possible heart disease or cancer. 5-0 Copyright © 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.