Dietary Constituents Affecting Plasma and Liver Cholesterol in Cholesterol-Fed Chicks

Studies were made of the effects of a number of dietary additions on plasma and liver cholesterol levels of chicks fed a diet containing 1% cholesterol and 4% cottonseed oil. When the cottonseed oil was omitted from the diet, only a moderate cholesteremia occurred. Paraffin oil at a 1% level or soy lecithin did not prevent hypercholesteremia, but this condition was prevented when a mixture of soy sterols and soy lecithin was fed. Mixed soy sterols, mixed sitosterols, beta-sitosterol, stigmasterol and ergosterol were effective inhibitors of the progressive rise of plasma cholesterol and of deposition of cholesterol in the liver. When cholesterol was fed at a constant level of 1% and soy sterols were fed at varying levels, an optimum effect in depressing both plasma and liver cholesterol levels was obtained when the ratio of soy sterols to cholesterol was 2:1 or 3:1. Esterification of the soy sterols with capric acid destroyed their ability to prevent an increase in plasma and liver cholesterol. Cholesteryl caprate, in contrast to free cholesterol, did not produce a marked hypercholesteremia, and relatively low liver levels of cholesterol were found when this substance was fed. A possible mode of action of these plant sterols in decreasing cholesterol absorption is discussed.