Functions of Lipids Natures way of condensing energy stores also insulates protects organs Source of calories 9 calories gram Flavor and tenderness of food Slow stomach emptying more satiating Source of essential fatty acids Lipids Types of Lipids Triglycerides Phospholipids Sterols Phospholipids Glycerol two fatty acids phosphorus Phosphorus part makes it soluble in water Fatty acids make it soluble in fat Therefore it can serve as an emulsifier Key role is in cell membranes Sterols Large molecules consisting of interconnected rings of carbon atoms with side chains of carbon hydrogen and oxygen attached Cholesterol o Is found in all animal cell membranes o Is nonessential o Forms plaques that cause atherosclerosis Cholesterol serves as the raw material for o Bile o Vitamin D o Steroid hormones including the sex hormones Triglycerides Main form of fat in food Made up of glycerol backbone and three fatty acids Fatty acids classified by length of carbon atoms and location of double bonds organization of hydrogen around the double bonds Saturated Fatty Acids Unsaturated Fatty Acids A fatty acid carrying the maximum of hydrogen atoms A fatty acid with less than maximum hydrogen atoms Monounsaturated FA Polyunsaturated FA Trans Fatty Acids Fatty acids with unusual shapes Arise when polyunsaturated oils are hydrogenated o Advantage control consistency and oxidation of fats o Disadvantage increases LDL Found in margarines shortenings baked goods Essential Fatty Acids Are made in limited amounts in the body Abundant in fish oils Lower blood pressure Prevent blood clot formation Protect against irregular heartbeats May reduce inflammation Essential for normal infant growth and development May support immune system May inhibit cancers Omega 3 Fatty Acids Linolenic Acid Docasahexaenoic Acid DHA Eicosapentaenoic Acid EPA Precursors of Omega 3 Eicosanoids Sources Fatty fish salmon tuna herring Flaxseed Canola and soybean oils Almonds walnuts spinach mustard greens Omega 6 Fatty Acids Linoleic Acid Precursors of Omega 6 Eicosanoids Sources Grains Fats and oils Eicosanoids Hormone like compounds that are made from EFAs and act through receptors on tissues to regulate many body responses Omega 6 cause inflammation blood clotting and tumor growth Omega 3 reduce inflammation blood clotting and tumor growth Imbalance of Omega 3 6 Similar enzymes required for processing too much of one interferes with the other American diet too low in Omega 3 o Average US intake of EPA and DHA is 150 mg day o Recommended is 600 mg day about 2 fatty fish meals per week to reduce CVD Increasing Omega 3 Eat fish 3 times per week Use flaxseed Farm raised products can be manipulated to contain more omega 3 eggs pork chicken farm raised fish Fish Oil Supplements May raise LDL High intakes may increase bleeding times High intakes may interfere with would healing High intakes may suppress immune function High intakes may upset the proper balance between omega 3 and omega 6 fatty acids Long term effects are unknown Fish and Mercury Some fish is contaminated with mercury yet fish is still a safe food source Safe for most people to consume two 3 ounce services per week of most ocean Pregnant or lactating women and children are sensitive to mercury 1 tuna can per fish week Benefits outweigh risks Salmon generally high in omega 3 and low in mercury fresh and farm raised Digestion and Absorption Digestion Depends on o Pre duodenal Lipase gastric o Pancreatic lipase o Bile acids for emulsification Absorption Short chain fatty acids o Portal vein blood to liver Monoglycerides and longer fatty acids Transport as Lipoproteins Chylomicrons from intestine to body Others produced in liver Lipase breaks down triglycerides into free fatty acids and monoglycerides o Get repackaged as triglyceride s for transport in chylomicrons a type of lipoprotein largest o Enter lymph and then blood stream o VLDLs Very Low Density Lipoproteins o LDLs Low Density Lipoproteins o Both take TG and cholesterol to body HDLs High Density Lipoprotein o Scavengers of cholesterol brings it back to liver Lipoprotein Profile Used to assess risk of heart disease o Total cholesterol o LDLs associated with increased risk less healthy want LOW o HDLs associated with decreased risk more healthy want HIGH Total Cholesterol Levels 200 mg dL Desirable level Lower risk for heart disease 200 239 mg dL Borderline high 240 mg dL High blood cholesterol More than twice the risk for heart disease LDL Cholesterol Levels 100 mg dL Optimal 100 129 mg dL Near Optimal Above Optimal 130 159 mg dL Borderline High 160 189 mg dL High 190 mg dL Very High HDL Cholesterol Levels 40 mg dL A major risk factor for heart disease 40 59 mg dL the higher your GDL the better 60 mg dL considered protective against heart disease Lifestyle changes to Lower LDL and raise HDL Lower LDL Raise HDL o Exercise o Decrease trans fat o Red wine Fat Replacers o Lower saturated and trans fat o Substitute monounsaturated and polyunsaturated fats for saturated o Lower cholesterol intake Olestra a non caloric artificial fat made from sucrose and fatty acids formerly called sucrose polyester o Indigestible o Excessive amounts have a laxative effect fat soluble vitamins added Simplesse a trade name for a protein based low calorie artificial fat approved by the FDA for use in foods o Heat sensitive o Used in frozen desserts Proteins and Amino Acids What do proteins do Build new tissue Functional unit a few to thousands of amino acids o Enzymes o Hormones o Antibodies Physiology metabolism o Fluid and electrolyte balance o Acid base balance o Energy o Transportation ex lipoproteins o Blood clotting How much protein do we need The DRI recommendation for protein intake depends on size and stage of growth DRI recommended intake is 0 8 gram per kilogram of body weight Minimum is 10 percent of total calories Athletes may need slightly more 1 0 gram per kg Protein Structure The amine group links with the acidic end of the next amino acid AA with electrically charged side chains are attracted to H20 AA with neutral side chains are repelled by water seeks each other Consequently proteins have very convoluted shapes Protein Denaturation Protein structure and function are disrupted by a variety of things o Heat o Acid o Alcohol o Base o Salts Amino Acid Metabolism Carried to the liver Used by the liver or released into the blood to be taken up by other cells Cells can then use the amino acids to Make their proteins for their
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