When you think of "bad" fats, think saturated. Most saturated fats can increase your blood cholesterol levels and risk of coronary artery disease. Usually solid or waxy at room temperature, saturated fat is most often found in animal products — such as red meat, poultry, butter and whole milk. Other foods high in saturated fat include coconut, palm and other tropical oils.

Along with saturated fat, trans fat may raise your blood cholesterol levels and increase your risk of heart disease. Trans fat — also referred to as trans-fatty acids — comes from adding hydrogen to vegetable oil through a process called hydrogenation. This makes the fat more solid and less likely to turn rancid. Hydrogenated fat is a common ingredient in commercial baked goods — such as crackers, cookies and cakes — and in fried foods such as doughnuts and french fries. Shortenings and some margarines are high in trans fat. Look for the words hydrogenated or partially hydrogenated in the list of ingredients to see if trans fat is included. Some margarine labels state if the product has no trans-fatty acids.

Polyunsaturated fat

Usually liquid at room temperature and in the refrigerator, polyunsaturated fats — when used instead of saturated fats — help lower blood cholesterol levels. In addition, they may help reduce the amount of cholesterol deposits on your arteries. Foods high in polyunsaturated fats include vegetable oils such as safflower, corn, sunflower, soy and cottonseed oils.

One type of polyunsaturated fat — omega-3 fatty acids — may be especially beneficial to your health. Omega-3 fat appears to decrease your risk of heart attack, protect against irregular heartbeats and lower blood pressure levels. It may even protect against some cancers. You'll find omega-3s mainly in fish — particularly in fatty, cold-water fish, such as salmon, mackerel and herring. Lesser amounts are in flaxseeds, soybeans and canola oil.

You can get sufficient omega-3 fatty acids by consuming two to three servings of fish per week.

Monosaturated fat

If used in place of other fats, monounsaturated fat can lower your risk of heart disease by reducing your blood cholesterol level. In addition, monounsaturated fat, unlike polyunsaturated fat, is more resistant to oxidation — a process that leads to cell and tissue damage in your body.

This type of fat is usually liquid at room temperature but may start to solidify in the refrigerator. Foods high in monounsaturated fat include olive, peanut and canola oils. Avocados and most nuts also have high amounts of monounsaturated fat.

written by Kate Hostvedt, 2004, Source: Mayo Clinic