Effect of beta-sitostanol (5 alpha-stigmastan-3 beta-ol) on cholesterol absorption from micellar solutions in jejunal loops in situ.

In situ jejunal loops were infused with micellar solutions of cholesterol with or without beta-sitostanol (5 alpha-stigmastan-3 beta-ol), and the uptake of 14C-cholesterol by the loop was followed for 20 minutes. It was found that beta-sitostanol, given as a 'solution-mix' (a solution resulting from the mixture of two separate micellar solutions of cholesterol and beta-sitostanol), at a concentration of 0.30 mM reduced cholesterol uptake. Substituting cholesterol for beta-sitostanol in the 'solution-mix' had no effect on cholesterol uptake by the loop. beta-Sitostanol at a concentration of 0.30 mM in the 'pre-mix' (a solution resulting from pre-mixing of the two sterols prior to preparation of the micellar solution) condition, had no effect on cholesterol absorption. Taken together, these results suggest that the concentration of beta-sitostanol-containing micelles is the important factor in its suppression of cholesterol absorption.