DIETARY PHYTOSTEROLS AS CHOLESTEROL-LOWERING AGENTS IN HUMANS

Phytosterols (plant sterols), abundant in fat-soluble fractions of pla nts, are consumed at levels of 200-400 mg/day in Western diets. Chemic ally resembling cholesterol, phytosterols inhibit the absorption of ch olesterol. Phytosterol consumption in human subjects under a wide rang e of study conditions has been shown to reduce plasma total and low de nsity lipoprotein (LDL) cholesterol levels; however, the response vari es widely. Greater cholesterol-lowering efficacy occurs with consumpti on of the saturated phytosterol sitostanol versus sitosterol or campes terol. Most studies report no effect of phytosterol administration in high density lipoprotein (HDL) cholesterol or triglyceride levels, alt hough certain evidence exists for an HDL cholesterol raising effect of sitostanol. Phytosterol absorption is limited, although serum phytost erol levers have proven to be important indicators of both cholesterol absorption and synthesis. Serum phytosterols correlate with HDL chole sterol level. In addition, higher phytosterol/cholesterol ratios appea r in HDL versus LDL particles, suggesting the existence of an intrinsi c phytosterol action, in addition to the extrinsic effect on cholester ol absorption. In conclusion, addition to diet of the phytosterol sito stanol represents an effective means of improving circulating lipid pr ofiles to reduce risk of coronary heart disease.