NHM 101 1nd Edition Lecture 11 Outline of Last Lecture I Sugar II Starch and Fiber III The Lipids Outline of Current Lecture IV Characteristics of fat and oils V Lipid Digestion and Absorption VI Functions of Lipids VII Fat Recommendations Current Lecture Hydrogenation Prolongs shelf life of food products by preventing oxidation Alters texture of foods o Hydrogenation make liquids more solid Most fats are partially hydrogenated Hydrogenation can cause trans fatty acids Phospholipids Phosphate group is water soluble Lipid component is fat soluble Widely known is Lecithin used as an emulsifier in mayo salad dressing and candy bar Sterols Multiple ring structure o Ex cholesterol Plant sterols o Similar in structure to cholesterol and can interfere with cholesterol absorption o Found in margarine and other functional foods Roles of cholesterol in the body o Used to make active form of Vitamin D These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Used by the liver to make bile o Used to make sterol hormones such as sex hormones adrenal hormones o Used in structural components of cell membranes Lipid Digestion Challenge is to keep the lipids mixed vs separation o Lipids hydrophobic o Digestive enzymes are hydrophilic Mouth o Some hard fats melt Stomach o Muscles contract to propel contents toward pyloric sphincter o Lipid particles broken down by gastric lipase Small Intestine o When fat enters cholecystokinin CCK is released which signals the release of bile from the gallbladder o Bile acts as an emulsifier so the enzymes can act on the fat o Most fat digestion occurs in the small intestine Pancreatic lipases and intestinal lipases Lipid Absorption Glycerol and short and medium chain fatty acids absorbed directly into the bloodstream Monoglycerides and long chain fatty acids from micelles spherical complex o Transported by proteins called chylomicrons Lipid transport is made possible by a group of vehicles known as lipoproteins o Chylomicrons Largest of the lipoproteins Least dense Get smaller as triglycerides are removed by the cells o Very Low Density Lipoproteins VLDL Composed primarily of triglycerides Transport lipids to the tissues Get smaller and more dense as triglycerides are removed and VLDL becomes LDL o Low Density Lipoproteins LDL Composed primarily of cholesterol with few triglycerides Transport lipids to the tissues o High Density Lipoproteins HDL Composed primarily of protein Transport cholesterol from the cells to the liver o Health Implications High LDL is associated with higher risk of heart disease and known as bad cholesterol High HDL appears to have a protective effect Functions of Lipids Part of every cell membrane Energy o Storage of triglycerides in adipose tissue is unlimited Insulation of body temperature Protection of vital organs In foods lipids function to o Give foods flavor and aroma o Transport fat soluble vitamins o Provide kcalories triglyceride Fat and Health Cardiovascular Disease o LDL cholesterol accumulates in arteries until blood flow is slowed or stops o Saturated and trans fats appear to be associated with a rise in LDL o Recommended lowering saturated fat and trans fats by decreasing animal fats high fat meat choose leaner cooking methods lower fat milk o Recommended increasing unsaturated fat by increasing olive oil nuts avocados and salmon Cancer o May promote cancer growth o Evidence not strong o Recommended to reduce red meat Obesity o More fat more calories Fat Recommendations Dietary Guidelines 2010 o AMDR for fat 20 35 calories from fat o Less than 10 of energy from saturated fat o Little to no trans fats o 300mg or less of dietary cholesterol Adequate Intake AI o 5 10 of calories from linoleic acid o 0 6 1 2 of calories from linolenic acid Americans Actual Intake Actual Intake of o Calories from fat on average is 34 o Calories from saturated fat is 11 o 6 grams of trans fats o Too much linoleic acid Omega 6 o Too little linolenic acid Omega 3 o Women consume 230mg cholesterol o Men consume 362mg cholesterol Real Life Recommendations Reduce consumption of animal fats Encourage fat in the form of oils Choose low fat cooking methods broiled baked grilled Emphasize whole grains fruits and vegetables that are low in fat Check the nutrition facts label for fat saturated fat and trans fat Food groups that contain a significant amount of fat are protein milk and milk products and processed grains