Effect of saturated and unsaturated fats on hepatic synthesis and biliary excretion of cholesterol by the rat

¹ Department of Internal Medicine, The University of Texas Southwestern Medical School, Dallas, Texas

In an attempt to elucidate the mechanisms by which saturated and unsaturated fats influence cholesterol metabolism, cholesterol synthesis in rat liver slices and the excretion of cholesterol end products into the bile of rats was studied during variations in the type and quantity of dietary fat. Neither 30% lard nor 30% corn oil diets had any effect on either the excretion of total cholesterol-C¹⁴ end products or of cholesterol itself into bile. Furthermore, the feeding of lard or corn oil, at either the 10% or 30% level, had no effect on the rate of conversion of acetate or mevalonate to cholesterol. These studies are interpreted as suggesting that the effects of saturated and unsaturated fats on cholesterol levels in rats are mediated at some phase of cholesterol metabolism other than the hepatic synthesis or hepatic degradation and excretion of this sterol.