Lipids are fatlike substances that include fatty acids (fats), oils, waxes and steroids, such as cholesterol. These compounds are within and between cell membranes, and they help protect nerves. Different forms of fatty acids include unsaturated fats, saturated fats and trans fatty acids. Both plant and animal sources contain different types of lipids that can provide beneficial and damaging health effects, depending on the type of lipid and the levels within the body.
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Food High in Unsaturated Fats
Unsaturated fats can be divided into two categories -- polyunsaturated and monounsaturated fats. According to the American Heart Association, all unsaturated fats have health benefits and can help reduce bad cholesterol. Polyunsaturated fats can be further broken down into omega-6 and omega-3 fats. Sources of omega-3 polyunsaturated fats include soybean oil, canola oil, flaxseed, walnuts and fatty fish, such as salmon, trout and herring. Sources of omega-6 polyunsaturated fats include soybean oil, corn oil and safflower oil. Monounsaturated fats can be found in nuts, vegetable oils, avocado, olive oil, canola oil and sunflower oil.
Foods Rich in Saturated Fat
Saturated fat is the primary cause of elevated blood cholesterol, according to the American Heart Association. Therefore, the organization recommends limiting your total saturated intake to less than 7 percent of your daily calories. These fats are found mainly in animal foods such as beef, pork, lamb, butter, milk and cheeses. Certain plant sources, such as coconut, coconut oil, cocoa butter and palm oil, also contain saturated fat. Harvard School of Public Health has ranked the top sources of saturated fat in the American diet. From highest to lowest, they include cheese, pizza, grain-based desserts, dairy desserts, chicken, sausages, franks, bacon, ribs, burgers, Mexican food and beef dishes.
Foods With Trans Fat
Trans fats can occur naturally in small amounts in meat products, though artificial trans fats are often used in processed foods and baked goods. "Dietary Guidelines for Americans, 2010" recommends eating as little trans fat as possible. According to the Centers for Disease Control and Prevention, trans fats raise bad cholesterol while decreasing good cholesterol and are responsible for as many as 20,000 heart attacks per year in the United States. Natural trans fats can occur in beef, pork, lamb, butter and milk. Artificial trans fats can occur in a variety of foods, including margarine, cookies, frozen pizzas, doughnuts and other deep-fried fast foods such as french fries.
Foods Containing Sterols
Sterols, a subdivision of steroids, are a class of lipids that include plant compounds as well as cholesterol, which is only found in animal food sources. Sterols are important in the formation of cell membranes. Plant sterols may be able to help reduce the risk for heart disease by lowering bad cholesterol, notes the Cleveland Clinic. While cholesterol is necessary, consuming high levels can increase your risk for heart disease. Foods with the highest levels of dietary cholesterol include chicken liver, beef liver, squid, eggs, shrimp, veal, lamb, beef, chicken, pork and lobster. Plant sterols can be found in small amounts in vegetables, fruits, nuts, seeds, legumes, cereals and vegetable oils.