LipidsFunctions 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 acidsTypes of LipidsTriglyceridesPhospholipidsSterolsPhospholipids- 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 membranesSterols- Large molecules consisting of interconnected rings of carbon atoms with side chains of carbon, hydrogen, and oxygen attached. - Cholesterolo Is found in all animal cell membraneso Is nonessentialo Forms plaques that cause atherosclerosis- Cholesterol serves as the raw material foro Bileo Vitamin Do Steroid hormones including the sex hormonesTriglycerides- 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 bondsSaturated Fatty Acids- A fatty acid carrying the maximum # of hydrogen atomsUnsaturated Fatty Acids- A fatty acid with less than maximum hydrogen atoms- Monounsaturated FA- Polyunsaturated FATrans Fatty Acids- Fatty acids with unusual shapes- Arise when polyunsaturated oils are hydrogenatedo Advantage: control consistency and oxidation of fatso 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 cancersOmega 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 greensOmega 6 Fatty Acids- Linoleic Acid- Precursors of Omega-6 EicosanoidsSources- Grains- Fats and oilsEicosanoids- 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 growthImbalance of Omega 3:6- Similar enzymes required for processing, too much of one interferes with the other. - American diet too low in Omega-3o 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 fishFish 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 fish- Pregnant or lactating women and children are sensitive to mercury (1 tuna can perweek)- Benefits outweigh risks- Salmon generally high in omega-3 and low in mercury (fresh and farm raised)Digestion and AbsorptionDigestion:- Depends on:o Pre-duodenal Lipase (gastric)o Pancreatic lipaseo Bile acids for emulsification- Lipase breaks down triglycerides into free fatty acids and monoglyceridesAbsorption:- Short chain fatty acidso Portal vein (blood to liver)- Monoglycerides and longer fatty acidso Get repackaged as triglyceride’s for transport in chylomicrons (a type of lipoprotein, largest)o Enter lymph and then blood stream Transport as Lipoproteins- Chylomicrons- from intestine to body- Others produced in livero 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 diseaseo Total cholesterolo 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: Optimal100-129 mg/dL: Near Optimal/Above Optimal130-159 mg/dL: Borderline High160-189 mg/dL: High>190 mg/dL: Very HighHDL-Cholesterol Levels<40 mg/dL: A major risk factor for heart disease40-59 mg/dL: the higher your GDL, the better>60 mg/dL: considered protective against heart diseaseLifestyle changes to Lower LDL and raise HDL- Lower LDLo Lower saturated and trans fato Substitute monounsaturated and polyunsaturated fats for saturatedo Lower cholesterol intake?- Raise HDLo Exerciseo Decrease trans fato Red wine?Fat Replacers- Olestra: a non-caloric artificial fat made from sucrose and fatty acids; formerly called sucrose polyestero Indigestibleo 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 sensitiveo 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 Enzymeso Hormoneso Antibodies- Physiology/metabolismo Fluid and electrolyte balanceo Acid-base balanceo Energyo Transportation (ex: lipoproteins)o Blood clottingHow 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 Heato Acido Alcoholo Baseo SaltsAmino Acid MetabolismCarried to the liver:- Used
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