History and development of plant sterol and stanol esters for cholesterol-lowering purposes

Plant stanol esters provide a novel approach to lowering plasma low-density lipoprotein (LDL) cholesterol by dietary means. Their development was preceded by a long period of research into the cholesterol-lowering properties of plant sterols and, recently, plant stanols. Both classes of compound competitively inhibit the absorption of cholesterol and thus lower its level in plasma. Initial impressions were that stanols were more effective and safer than sterols, but the negative outcome of a study led to the recognition that the lipid solubility of free stanols was very limited. This was overcome by esterifying them with fatty acids, with the resultant stanol esters being freely soluble in fat spreads. This led to the launch of Benecol (margarine; Raisio Group, Raisio, Finland) in 1995. The coincident publication of the year-long North Karelia study conclusively demonstrated the long-term LDL-lowering efficacy of plant stanol esters. Variables that might influence the efficacy of stanol esters include dose, frequency of administration, food vehicle in which the stanol ester is incorporated, and background diet. The effective dose is 1 to 3 g/day, expressed as free stanol, which, in placebo-controlled studies, decreased LDL cholesterol by 6% to 15%. This effect is maintained, appears to be similar with once-daily or divided dosage, and is independent of the fat content of the food vehicle. Short-term studies suggest that equivalent amounts of plant sterol and stanol esters are similarly effective in lowering LDL, the main difference being that plasma plant sterol levels increase on plant sterols and decrease on plant stanols. The clinical significance of these changes remains to be determined.