The body stores energy primarily in the form of fats. Fats enable absorption of Vitamins A, D, E and K and supply essential fatty acids omega-3 and omega-6, which the body cannot produce itself. Because of their high caloric content, all fats should be consumed in moderation.

Trans fatty acids are unsaturated fatty acids that occur naturally in some meat and dairy products. Most trans fatty acids result from a process called partial hydrogenation, which turns liquid vegetable oils into a solid or semi-solid form.

Commercial food makers long have used partially hydrogenated vegetable oil in hard margarines, snack foods and baked goods because of its resistance to heat and spoilage. These characteristics translate into better cooking performance and longer shelf-life.

When consumption of saturated fats was linked to high cholesterol, most restaurant chains switched from beef tallow or lard, which are high in saturated fat, to partially hydrogenated oil for frying, believing it to be a healthier, unsaturated fat.

Scientific research has shown that trans fats increase low-density lipoproteins (LDL or “bad” cholesterol) and reduce high-density lipoproteins (HDL or “good” cholesterol), which help the body eliminate LDL cholesterol. Saturated fats increase both LDL and HDL, but the overall effect on health is negative.

Trans fats and saturated fats both increase the risk of coronary heart disease, stroke and other health conditions, while monounsaturated and polyunsaturated fats lower the risk. Therefore, it is generally recommended that people replace saturated and trans fats in their diet with monounsaturated and polyunsaturated fats.