Plant sterols and stanols are similar in chemical structure to cholesterol, differing in their side chain configuration. The mechanism by which they lower cholesterol is thought to involve inhibition of cholesterol absorption. A number of products containing plant sterols are now available. A limitation on the development of such products is the poor water solubility of plant sterols. The most common solution is to esterify plant stanols or sterols with fatty acids to enhance availability in food fats such as margarines and salad dressings. A number of studies have shown the efficacy of plant stanol- and sterol-enriched margarines for lowering cholesterol. However, there have been no studies demonstrating that consumption of these stanol ester-containing margarines influences the incidence of coronary heart disease.