Effects of Low Dose Phytosterols on Cholesterol Absorption in Man

Abstract

The plasma cholesterol lowering action of phytosterols has been known for many years (1 – 3). It has generally been thought that large doses of phytosterols are required to obtain a significant reduction in plasma cholesterol. The average diet provides a daily intake of plant sterols in the range of 250 – 300 mg per day, and the effects of these intakes on plasma cholesterol are probably negligible. However, when plant sterols are fed at a level of 10 – 15 g per day, a distinct lowering of cholesterol occurs? reductions in the range of 10 – 20 % have usually been reported (1 – 4). The phytosterols, of which 3-sitosterol is usually the major component, cause a decrease in plasma cholesterol by interfering with intestinal absorption of both endogenous and exogenous cholesterol. This inhibition of cholesterol absorption leads to a marked increase in fecal excretion of neutral steroids. The fall in plasma cholesterol during phytosterol feeding is probably due to an increased drain on tissue pools of cholesterol, especially the liver pool. Although phytosterol feeding causes a drain on body cholesterol by interrupting its intestinal reabsorption, the degree of cholesterol lowering is limited due to release of feedback inhibition on cholesterol synthesis (4). After a period of a few weeks of phytosterol administration, a new steady state is reached in which plasma cholesterol concentrations are reduced but at the same time rates of cholesterol synthesis are enhanced.