Saturated fats
Are solid at room temperature. Most saturated fatty acids raise blood cholesterol levels; however, stearic acid, the most common saturated fatty acid found in beef, has little effect on blood cholesterol. Foods higher in saturated fats include processed and deep fried foods made with lard, shortening and tropical oils (palm kernel oil, coconut oil), butter, full-fat milk and cheese products, processed meats, meat untrimmed of exterior fat and poultry with the skin.

Monounsaturated fats
Are liquid at room temperature. Monounsaturated fats lower or have little effect on blood cholesterol levels. Foods higher in monounsaturated fats include certain nuts and canola, olive and peanut oils.

Polyunsaturated fats
Are also liquid at room temperature. Polyunsaturated fatty acids lower blood cholesterol levels. Foods higher in polyunsaturated fats include certain nuts, fish, safflower, sunflower and corn oils.

Trans fats
Are formed in the hydrogenation of unsaturated fats, a process used to turn liquid oil into spreadable margarines. Trans fatty acids raise blood cholesterol levels. Foods higher in trans fatty acids include foods made with hydrogenated vegetable oils such as many margarines, cookies, crackers, french fries and potato chips. Trans fatty acids occur naturally in ruminant animals (e.g., cattle, goats, sheep) due to the natural fermentation process in the rumen. They are different in structure from the trans fatty acids formed from hydrogenating vegetable oils and do not appear to have the same negative relationship with coronary heart disease. Reference

Ascherio, A., Hennekens, C.H., Buring, J.E., Master, C., Stampfer, M.J., & Willet, W.C. (1994). Trans-fatty acids intake and risk of myocardial infarction. Circulation, 89, (1), 94-101.

Pietinen, P., Ascherio, A., Korhonen, P., Hartman, A.M., Willet, W.C., Albanes, D., &Virtamo;, J. (1997). Intake of fatty acids and risk of coronary heart disease in a cohort of Finnish men. American Journal of Epidemiology, 145, (10), 876-887.

Willet, W.C., Stampfer, M.J., Manson, J.E., Colditz, G.A., Speizer, F.E., Rosner, B.A., Sampson, L.A., & Hennekens, C.H. (1993). Intake of trans fatty acids and risk of coronary heart disease among women. The Lancet, 341, 581-585.

Gray-Donald K, Jacobs-Starkey L, Johnson-Down L. Food Habits of Canadians: Canadians are eating a lower fat diet than a generation ago. Can J Public Health 2000;91:381-385.