Functional foods enriched with plant sterols and stanols are on sale in many countries. Due to their structural similarity with cholesterol, these additives lower intestinal absorption of cholesterol, resulting in a 10-15% reduction in LDL-cholesterol when their daily intakes are 2-3 g. They are also effective as part of a cholesterol-lowering diet and in combination with cholesterol-lowering drugs. Estimates for the absorption of plant sterols (sitosterol and campesterol) and of campestanol are around 10%, and for sitostanol less than 5%. Lipid-standardized plasma levels are very low, but increase when statins are used. Extensive toxicological evaluation studies have not revealed any harmful side-effects. In human studies, side-effects were comparable to placebo treatment. However, lipid-standardized levels of the hydrocarbon carotenoids may decrease, without leaving the normal range. Together, these findings indicate that these functional foods have great potential in the prevention of coronary heart disease. However, post-marketing surveillance for example for functional foods in general is necessary to monitor possible adverse effects and describe consumers and consumption patterns.