Fat

Utilization Energy Storage Insulation Body structure Cell membranes Protection Essential fatty acids (linoleic and linolenic acid) controlling inflammation, blood clotting, and brain development Hormones & bile salts Vitamin Carrier (Fat soluble vitamins A, D, E, K) Palatability and satiety of foods Monounsaturated | Polyunsaturated | Omega-3 | Saturated | Trans-unsaturated Monounsaturated Fats Liquid at room temperature Found in canola oil, olives, olive oil, nuts, peanut oil, and avocados See Exchange List and Comparison of Fats Preferred in the diet Can lower LDL (bad cholesterol) and maintain HDL (good cholesterol) if substitued for other less healthy fats Contain essential fatty acids which help to reduce cholesterol deposits Polyunsaturated Fats Liquid at room temperature Found in safflower, sesame, corn, cottonseed, and soybean oils See on Exchange List Linked to decrease in mortality (Hu 2005) Large intake may increase the risk for some types of cancer Omega-3 fatty acids Type of Polyunsaturated fatty acid Benefits Maintains cardiovascular health reduce triglyceride levels Maintains mental clarity Anti-inflammatory properties may help arthritis and lupus helps lubricate joints Omega-3 sources Found especially in fish and fish oils Salmon, mackerel, lake trout, herring, sardine, albacore tuna, cod, halibut, mahi-mahi, catfish, flounder, tilapia, bluefish, whitefish 8 oz (225 g) of fish (low mercury) per week recommended See Omega-3 content in Seafoods Small concentrations in green leafy vegetables (kale, collard greens) and certain algae Flaxseed, walnuts, soy, avocados Canola, soybean, walnut, echium, and flaxseed oils high lignan flaxseed oil Canola Oil contain precursors of Omega-3 Fatty acids (DHA and EPA) Foods fortified with DHA from algea fish get their DHA from algea Grass-feed animals provide more omega-3 fats, whereas grain fed animals provide more omega-6 fats Consider taking fish oil or flaxseed oil if diet is insufficient in Omega-3 No mercury, dioxin, and PCBs often found in fish Patients with congestive heart failure or chronic recurrent angina should not be urged to consume fish oil or more fish (Leaf 2006) Ratio of Omega-6 to Omega-3 in diet Recommended ratio is between 2:1 and 4:1 Average American Diet is between 10:1 and 30:1 Too much Omega-6 promotes inflamation Increaseses risk of coronary heart disease and other chronic illnesses May be harmful if not accompanied by adequate Omega-3 to provide protective effects Omega-6 found in cereals, some nuts, whole grains, and vegetable oils Omega-6 to Omega-3 Ratios in oils: Flaxseed Oil (1:3) Canola Oil (2:1) Olive Oil (13:1) Corn Oil (46:1)   Saturated Fats Solid at room temperature Found in animal fats meat, dairy, eggs Found in some plant sources cocoa butter, coconut, palm and palm kernel oils Saturated fats can be converted to cholesterol or LDL Main cause of high blood cholesterol (American Heart Association) Double risk of CHD for every 15% increase in saturated fat calories (instead of carbohydrate calories) (Hu 1997) See Saturated Fats Exchanges and Additional Fat Exchanges Trans-unsaturated fat Processed foods and oils provide 80% of trans fats in diet Examples margarine (up to 15% trans fat by weight) baking shortening (30% of trans fat) partially hydrogenated and hydrogenated oil (up to 45% trans fat) See Exchange List Found in fast foods and fried food Peanut butter (partially hydrogenated) snacks foods and many baked goods replaces butter and lard Created industrially through partial hydrogenation of plant oils process developed in early 1900s first commercialized as Crisco in 1911 Benefits extends shelf life and decreases refrigeration requirements less expensive than semi-solid oils such as palm oil can be reused longer in deep frying without going rancid baked good look better, browns more evenly vegetarians can consume foods made vegetable trans fats as opposed to butter and lard Animal sources only provide 20% of trans fats in form of conjugated linoleic acid and vaccenic acid naturally occurring amounts in meat and dairy products 2-5% of total fat Health impact Non-essential Consumption increases risk of coronary heart disease (CHD) Increased risk at 1 to 3 percent of total energy intake (Mozaffarian 2006) Double risk in CHD for every 2% in trans fat calories consumed (instead of carbohydrate calories) (Hu 1997) It is estimated between 30,000 and 100,000 cardiac deaths per year in the United States are attributable to the consumption of trans fats (Mozaffarian 2006) Cholesterol effects Increases LDL (bad cholesterol) Lowers HDL (bad cholesterol) Example content doughnut (medium): 3.2 g of TFA french fries (large): 6.8 g of TFA Recommendations Trans fats be limited to less than 1% of overall energy intake (World Health Organization 2003, American Heart Association) Example: consume less than 3 grams of trans fat on a 3000 Calorie diet Also see Comparison of Dietary Fats American Dietary Guidelines (2005) A high fat intake (greater than 35% of calories) associated with higher saturated fat intake keep saturated fat below 10% of calories more difficult to avoid consuming excessive calories Low fat intake (less than 20% of calories) increased risk of inadequate intakes of vitamin E and essential fatty acids may contribute to unfavorable changes in HDL and triglycerides Weight Management Dietary fats are stored and mobilized easily It takes more energy for the body to convert carbohydrates or protein to body fat than it does to convert dietary fat to body fat see thermic effect of food Typically, less calories are consumed when eating a low fat diet (Lissner 1987, Thomas 1992). A reduction in dietary fat without a reduction in total calories or an increase of physical activity only produces small if any changes in body fat mass (Leibel 1992). Effects on Endurance High fat diets may limit endurance if carbohydrates are low and body is accustome to a higher carbohydrate diet. A high fat diet may actually increase endurance in certain elite athletes particularly if they have adapted to such a diet Studies are mixed as to whether it increases endurance Ideal would be fat adaptation with high glycogen and intramuscular triglyceride stores Fat adaptation occurs after five days of being on the high fat diet and persists during one day of carbing up (Burke 2000) There is no net glucose synthesis from lipids except from glycerol portion - 10% by weight