Consumers have been wary about saturated fats since 1961, when the American Heart Association (AHA), Dallas, first warned Americans to reduce their saturated-fat intake due to overwhelming evidence linking it to heart disease. Saturated fats raise blood levels of LDL cholesterol and total cholesterol. High LDL cholesterol and total cholesterol levels in the blood are major risk factors for coronary heart disease (CHD), which leads to heart attacks and an increased risk of stroke.
Most health organizations agree that Americans need to reduce their saturated-fat intake. According to "Healthy People 2000", a report released by the National Center of Health Statistics, Hyattsville, MD, less than 10% of dietary energy should come from saturated fats. The Chicago-based American Dietetic Association (ADA) recommends that 7% to 10% of total calories consumed come from saturated fats. The AHA suggests a saturated-fat plus trans-fat intake of less than 10% per day (less than 7% for those with CHD, diabetes or high LDL cholesterol). And the National Cholesterol Education Program (NCEP), Bethesda, MD, recommends dietary intervention as a primary prevention method against elevated blood LDL-cholesterol levels. NCEP also suggests "therapeutic lifestyle changes," including less than 7% of total calories coming from saturated fats. Scope of saturated fatsSaturated fats, usually solid at room temperature, are found primarily in animal sources such as meat, poultry and fat-containing dairy products, and some vegetable oils like coconut, palm and palm-kernel. A saturated fatty acid has the maximum number of hydrogen atoms attached to every carbon atom, making them both "saturated" with hydrogen atoms. The most common saturated fatty acids in foods are palmitic, stearic and myristic acids. Their chemical structure makes saturated fatty acids more stable than unsaturated fatty acids, which aids in preventing rancidity, off-flavors or odors in foods. Research leads scientists to believe that not all saturated fatty acids are created equal when it comes to their effects on plasma lipids. Myristic acid is the most hypercholesterolemic saturated fatty acid. Stearic acid, common in beef, cocoa powder and fully hydrogenated vegetable oils, appears to have a neutral or possible lowering effect on serum-cholesterol levels. This has prompted some scientists to call for a different grouping for stearic acid when it comes to saturated-fat guidelines. However, FDA continues to include stearic acid under its definition of saturated fat for labeling purposes. The AHA encourages more research on saturated fatty acid's function on blood cholesterol, and scientists are currently pursuing the ideal fatty-acid profile for new oils. Let's not forget hydrogenated fats. Many food manufacturers turned to hydrogenated vegetable oils as replacements for saturated animal fats, and they lend a hand in the stability and texture of food products from margarine to baked goods. The hydrogenation process adds hydrogen molecules directly to a monounsaturated or polyunsaturated fatty acid, thus making it more saturated. Trans-fatty acids, under fire for raising LDL cholesterol levels, are also formed during partial hydrogenation of vegetable oils. Further insightsSkhinder Kuar, Ph.D., Memorial University, St.John's, Newfoundland, studies the regulation of genes involved in cholesterol metabolism by saturated fats. Her work indicates that fats act as ligands to bind transcription factors and regulate the cholesterol ester transfer protein gene (CETP), resulting in the production of LDL or HDL cholesterol. The saturated fats bind the transcription factors to the gene that produces CETP, thus sending more LDL into the bloodstream. Another study, conducted at the USDA Human Nutrition Research Center on Aging at Tufts University, Boston, fed identical twin sets two diets with equivalent palatability, fiber content and calories per ounce, one containing 40% fat and the other 20% fat. Four sets of twins ate more calories from the high-fat menu, while the other three sets preferred the low-fat menus, suggesting that genetic influence may result in the choice of certain diets.
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Taking Stock of Saturated Fats
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