Influence of dietary cholesterol on excretion of cholesterol-4-C14 by the rat

Abstract

The influence of dietry cholesterol on the excretion of cholesterol-4-C14 has been studied in rats pair fed isocaloric quantities of purified diets supplemented with varying amounts of cholesterol and either oleic or linoleic acid. Of the C14 excreted over an 8-day period, slightly more than half was present in the neutral sterol fraction of feces from rats fed sterol-free diets. The addition of dietary cholesterol, however, under circumstances where significant cholesterol absorption was promoted by the addition of fatty acids to the diets, resulted in a reversal of this ratio so that the bile acid fraction accounted for the major portion of excreted cholesterol-C14. Cholesterol balance data revealed that the degradation rate of cholesterol in these animals rose to about 17–20 mg/day. These data are interpreted as demonstrating that the amount of absorbed dietary cholesterol plays a crucial role in determining both the relative and absolute importance of the two major routes of cholesterol excretion.