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Lecture 5

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NUTR 1010
Jess Haines

Week Four – October 1 , 2012 LIPIDS Lipids are a large group of molecules that are not soluble in water and all are non- polar molecules. LIPIDS WE EAT Triglycerides - 95% of our dietary lipid; usually what it means when we say “fat” - We eat triglycerides and store our body fat as triglycerides - Made of 1 glycerol molecule Fatty Acids - Different fatty acids give triglycerides different properties Lengths Length affects how it is digested and processed in the body; its function in the body, and its properties before/when you eat it; ex. Lauric acid – fat in chocolate that makes it feel nice in your mouth, medium length. Short chain: fewer than 6 carbon atoms Medium chain: 6-12 carbon Long chain: 14 or more carbons Saturation Saturated fats (SFA) have no double bonds, while unsaturated fats have 1 or more double bonds (which removes one of the hydrogen molecules). Monounsaturated (mufa) = 1 double bond Polyunsaturated (pufa) = 2 or more double bonds - Affects whether food is a solid or liquid at room temperature (butter is very saturated); how they are processed in the body (poly, do not stack because of the bonds, so molecules can shift around; liquid at room temp); health. Foods with Saturated Fats: all animal foods, ice cream, butter, tropical oils (coconut oil). Monounsaturated: olive oil, canola oil. Polyunsaturated: any vegetable oil, canola, safflower, corn oil, fish, and nuts; omega 3. Where is the double bond? - The bond closest to the end of the fatty acid o Omega end o This bond affects how your body uses the fat. - Omega 3 fatty acids = double bond at the third carbon from the end. th - Omega 6 fatty acids = double at the 6 carbon Shape Cis: hydrogren molecules on the same side as the double bond, creating a kink; most fats in our diet are in the Cis shape Trans: hydrogen molecules on opposite sides; even though it has double bond, acts as though it doesn’t; trans fats can pack tightly like saturated fats and are hard at room temp; is written on food labels while cis is not (assumed to be in everthing); found in milk, cheese, and beef; hydrogenated fats: Crisco, chips, margarine, fries, peanut butter. Name your fatty acid* they are given common names and numerical notations. Ex. 18:2 -3 Phospholipids Consists of a glycerol backbone with two fatty acids and a compound that contains phosphate. Sterols A large group of hydrophobic compounds; found in plant and animals; most common one in animals: cholesterol. Plant sterols are good for heart health; body absorbs sterols instead of cholesterol; functional food – helps fight disease. FAT DIGESTION Mouth: chewing and lingual lipase Stomach: churning into small droplets, gastric lipase Small intestine: bile emulsifies fats into small droplets (micelles); pancreatic lipases break fatty acids off of glycerol; free fatty acids and Mono glycerides FAT ABSORPTION Lipids are not soluble in water, so digesting them requires the help of digestive enzymes from pancreas and bile from gall bladder; cells of intestinal wall secrete hormone (CCK) which causes the gallbladder to contract and release bile into the duodenum (small intestine); it slows down the movement while enzymes break the lipids down; micelles transport the products to the enterocytes of the small intestine. broken down products, along with free chloestoral are trapped in the micelle, then they are transp
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