Saturated and trans fats have reputations for being villains of the fat world, since overeating them is often associated with increased cardiovascular disease risk. However, saturated fat, which naturally exists in beef, pork, full-fat dairy products, butter and tropical oils, may provide health benefits when you consume it. By contrast, the majority of trans fats come from chemically processing unsaturated fats, have no known health benefits and may increase your risk for cardiovascular disease.
The fatty acids in the foods you eat consist of carbon and hydrogen molecules strung together in a chain. A saturated fatty acid has the maximum number of hydrogen molecules attached to its carbons, while an unsaturated fatty acid has double bonds between one or more sets of carbons, which changes its molecular arrangement. A fatty acid's structure dictates its function in your body, and the proper balance of saturated and unsaturated fat is important for building cell membranes, synthesizing hormones and absorbing fat-soluble vitamins. Food companies use a chemical process to add hydrogen back to polyunsaturated fatty acids, creating trans fatty acids. This process also changes the fatty acid structure to one your body can't use, likely interfering with proper function.
Modest saturated fat intake helps maintain the structure of your cell membranes, improves absorption of calcium in your bones, aids in proper utilization of essential fatty acids and provides fuel for your heart. A 2010 analysis of several research studies in the journal “Lipids” showed that most of the studies didn’t find a direct link between saturated fat intake and cardiovascular disease risk, contradicting the traditional notion of saturated fat as an artery-clogger. Short- to medium-chain saturated fats in tropical oils such as coconut oil are metabolized differently than their long-chain counterparts, making them more likely to be used for energy rather than stored as fat.
Trace amounts of trans fats exist in animal products such as beef, pork, lamb, butter and milk fat. However, the majority of trans fats in your diet come from margarine, shortening and the partially hydrogenated oils used in packaged crackers, cookies, frozen pies and french fries. High intake of trans fats lowers your good HDL cholesterol, increases your bad LDL cholesterol and blood triglycerides and may increase markers of inflammation, increasing your heart disease risk. The enzymes involved in fat breakdown may not recognize these manmade trans fats, making it harder on your body in terms of using them for vital functions.
Since most trans fats come from chemical processing and exist in foods with little nutritive value, limit your trans fat intake to 1 percent of your total calories, or 2 grams on a 2,000-calorie-per-day diet. While saturated fat may not be as harmful to your heart health as previously thought, it is a dense form of calories and thus easy to overeat. Limit your saturated fat intake to 10 percent of your overall calories, or 20 grams on a 2,000-calorie diet.
Gina Battaglia has written professionally since 2006. She served as an assistant editor for the "International Journal of Sports Medicine" and coauthored a paper published in the "Journal of Strength and Conditioning Research." Battaglia completed a Doctor of Philosophy in bioenergetics and exercise science at East Carolina University and a Master of Science in biokinesiology from the University of Southern California.