Sklan, D., Fac. Agric., Hebrew Univ. Jerusalem, Rehovot, Israel
Budowski, F., Fac. Agric., Hebrew Univ. Jerusalem, Rehovot, Israel
Hurwitz, S., Fac. Agric., Hebrew Univ. Jerusalem, Rehovot, Israel

Twenty day old chicks were fed for 7 days a diet containing 0.5% cholesterol, with or without 1% soy sterols. During the last 4 days, yttrium 91 was included in the diet to serve as a nonabsorbable reference substance for the determination of rates of net absorption and secretion of cholesterol and bile acids. Dietary soy sterols reduced the size of the liver plasma cholesterol pool, decreased the daily net absorption of both cholesterol and bile acids between the duodenum and lower jejunum and also depressed their daily endogenous secretion into the duodenum. In addition, soy sterols exerted a marked inhibitory action on the absorption of steroids between the lower jejunum and the lower ileum. The reduced ileal absorption accounted entirely for the effect of soy sterols on the overall net absorption of cholesterol, which dropped from 22% in the cholesterol group to 6% in the group receiving soy sterols. Overall net absorption was less for phytosterols than for cholesterol, campesterol being taken up to a greater extent than stigmasterol and β sitosterol.