NTR 213 Chapter 5 notes: Lipids
NTR 213 Chapter 5 notes: Lipids NTR 213-05
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This 17 page Bundle was uploaded by Elizabeth Weathers on Tuesday February 16, 2016. The Bundle belongs to NTR 213-05 at University of North Carolina - Greensboro taught by Laurie H. Allen in Winter 2016. Since its upload, it has received 64 views. For similar materials see Introductory Nutrition in Environmental Science at University of North Carolina - Greensboro.
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Date Created: 02/16/16
Roles of Fat In food: provide texture, flavor, aroma In our body: Help cushion our internal organs Provide insulation lubricate body surfaces Necessary for cell membranes Myelin coating for brain and nerves Provide energy and storage of energy Absorption of fat soluble vitamins (Vitamin A, D, E, and K) Needed for steroid hormones Essential fatty acids needed for growth, fertility, eye health, brain development and immunity among other roles Sources of Dietary Fats Animal sources: Plant sources: “Hidden” dietary fat: Meat vegetable oils French fries Cheese nuts Pizza Butter avocados pasta dishes Lard coconut baked goods salad dressings Lipids Called ‘fats’ in the diet Triglycerides: Phospholipids: Sterols: Made up of 3 fatty acids & Lipids with a unsaturated steroid 1 glycerol phosphate group alcohols Saturated fats In cell membranes in cell membranes Unsaturated fats Starting material starting material Cholesterol Triglyceride: Glycerol, fatty acids: chains of carbon atoms, acid at end Phospholipid: Glycerol, fatty acids, phosphate group Sterols: interconnected rings of carbon atoms Fatty acids in Triglycerides Chain of carbon atoms Each carbon can form 4 bonds Vary in length and location of carbon- carbon bonds in the chain Classified as saturated or unsaturated Carbon bonding Saturated vs. Unsaturated Fats Saturated fats: carbons are saturated by hydrogens Unsaturated fats: carbons not saturated Saturated vs. unsaturated fats in foods Butter, Cheese, Red meat are high in Corn, Safflower, Canola oil are high saturated fatty acids in unsaturated fatty acids Unsaturated fatty acids: Monounsaturated vs. Polyunsaturated fats Monounsaturated fats: one double bond Canola oil Peanut oil Olive oil Polyunsaturated fats: more than one double bond Omega-6 corn oil Omega-3 (salmon, flax seed) Omega-3 vs. Omega-6 Polyunsaturated fats Omega-3: first double bond at 3d bond from omega end Omega-6: first double bond at 6h bond from omega end Essential fatty acids Essential vs. non-essential fatty acids Essential fatty acids cannot be made in the body, so they are essential in the diet Needed for cell membrane, growth, brain development Ex: linoleic acid (omega-3) and alpha-linolenic (omega-6) Non-essential fatty acids can be made by the body, so they are not essential in the diet or that are not necessary for the body Omega-9 fatty acids saturated fatty acids Hydrogenation: Cis vs. trans-fats Hydrogenation: hydrogen atoms are added to carbon- carbon double bonds making an unsaturated fatty acid more saturated. Increases shelf life. INCREASES RISK OF HEART DISEASE Trans-fat (trans-fatty acids) Phospholipids Fatty acids at one end soluble in fat, phosphate end soluble in water Act as emulsifiers Component of cell membranes Used to synthesize acetylcholine Present in small amounts in food and in the body Sterols Best known sterol is cholesterol Cholesterol is produced by liver and consumed in diet (animal sources only) Needed for cell membranes and to make other sterols and hormones: Vitamin D bile acids, testosterone and estrogen Lipid Digestion and Absorption Bile Bile is stored in the gall bladder before entering the small intestines Bile emulsifies (breaks up larger particles) dietary fat so it is more accessible to lipases (lipid-digesting enzymes) Dietary fiber binds cholesterol to keep it from being reabsorbed into the body from the small intestines (so more is excreted from the body) Lipoproteins in blood Lipid Transport and Delivery Lipid transport and delivery: Lipoproteins Dietary lipids (such as cholesterol and triglycerdies) are packaged into lipoprotein particles Chylomicrons Transport triglycerides, cholesterol, and fat-soluble vitamins from the small intestines to the liver Triglycerides in chylomicrons are broken down into glycerol and fatty acids by lipoprotein lipase (in blood vessels) to cross membranes then are reassembled into triglycerides in cells Chylomicron remnants are returned to the liver VLDL particles are made in the liver particles function similar to chylomicrons (transport triglycerides which are broken down by lipoprotein lipase) LDL particles deliver cholesterol to cells LDL particles bind to LDL receptors on cells to help cholesterol move from the blood into cells HDL particles transport cholesterol from cells to the liver The liver uses cholesterol to make bile Lipid Functions Necessary to maintain health Absorb fat soluble vitamins Component of cell membranes and myelin coating Insulation Lubrication Stored energy EFA: eye, brain development, fertility, eicosanoids Conversion of fatty acids to energy Feasting vs. Fasting Eicosanoids Synthesis Ratio of Omega-3s to Omega-6s Ratio of Omega-3 to Omega-6 affects health US diet contains higher ratio of omega-6 to omega- 3 Omega-3 anti- inflammatory, Omega-6 pro- inflammatory Atherosclerosis development Blood vessel injury, inflammation and LDL oxidization generates plaques blood vessel walls in atherosclerosis Antioxidants (found in fruits and vegetables) can limit oxidation of LDL Atherosclerosis can narrow blood vessels and limit blood flow to tissues so that fewer nutrients and oxygen molecules are delivered Risk Factors for Atherosclerosis and Cardiovascular Disease Diet Smoking Diabetes High blood pressure (hypertension) Obesity Sedentary Blood lipids (high LDL, triglycerides; low HDL) Family history, age, gender, race LDL vs. HDL in heart disease LDL LDL particles transport cholesterol from the liver to body cells Work to decrease your blood levels of LDL (“you want your low to be low”) HDL HDL particles transport cholesterol from body cells to the liver so they can be excreted Work to increase your blood levels of HDL (“you want your high to be high”) Decrease your LDL and increase HDL Decrease dietary trans-fat, saturated fat Increase dietary polyunsaturated fats and monounsaturated fats Quit smoking Exercise Mediterranean and DASH diets may Decrease Cardiovascular Disease Total Diet 1/g day of EPA and DHA Replace sat fat with MUFA and PUFA Consume 5 oz nuts per week High intake of fruits and vegetables (especially bright colors) Fewer animal proteins Avoid trans fat High total fiber Limit sodium < 2400mg Dietary Fat and Obesity Fat has 9 calories (kcals) per gram Carbohydrates & proteins have 4 calories per gram Ex: 1 teaspoon of olive oil contains 5 grams of fat, 5 grams x 9 kcals/gram = 45 kcals from fat Fat is efficiently stored Dietary recommendations Total fat: 20%–35% of total calories 30–40% for ages 1–3 & 25–35% for ages 3–18 Saturated fat: less than 7% of total calories Cholesterol: less than 300 mg per day-no longer part of dietary guidelines Trans-fat: limit Food Labels Fat Replacers Types of Fatty Acids Fatty Acids Saturated Fats Unsaturated Fats Animal fats, tropical fats Industrialized (trans- fat) Monounsaturated Baked goods, Polyunsaturated Olive oil, canola oil processed foods Omega 3 Omega 6 Flax seed, walnuts, Vegetable oils, nuts cold-water fatty fish
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