The Interrelated Effects of Dietary Cholesterol and Fat upon Human Serum Lipid Levels *

Abstract

In diets of mixed, natural foods controlled in fat content, dietary cholesterol influenced greatly the serum cholesterol and phospholipid levels. The removal of cholesterol from the diet produced a decrease of 38 mg.% in the mean serum cholesterol concentration despite a diet containing a large quantity of saturated fat. The addition of 725 mg of dietary cholesterol caused an increase in the mean serum cholesterol concentration even when the diet contained a high content of polyunsaturated fat. The concentration of serum lipids remained unchanged during two periods of cholesterol-free diets when the fatty acid composition of the dietary fat was made more polyunsaturated and less saturated (from an I number of 63 to 100). The results of this study emphasize again the important influence of dietary cholesterol upon the serum lipids in humans. The effects of changes in dietary fat composition in the ranges tested were minor in comparison to those caused by changes in the dietary intake of cholesterol.