Dietary Protein and the Serum Cholesterol Level in Man

Abstract

Groups of physically healthy, schizophrenic men were metabolically stabilized on a typical American diet and then were maintained at calorie equilibrium under rigid control in dietary experiments lasting 16 or more weeks. The response of the total serum cholesterol to a change from a low- to a high-fat intake was the same in one group of men receiving 83 g of protein daily as in a matched group on the same diet except for the isocaloric substitution of an extra 47 g of skimmed milk protein for carbohydrate in the diet. The cholesterol in the beta-lipoprotein fraction in the serum behaved as did the total serum cholesterol. Two groups of subjects were maintained on a low-protein intake (averaging 8.6 per cent of calories from proteins), were changed for four weeks to a high-protein intake (17.7 per cent protein calories) and then were changed back to the low-protein intake, all at a constant fat intake. There was no significant change in the serum cholesterol level in either group at any time. An increase, maintained for eight weeks, of 1000 mg per day in the dietary cholesterol intake, had no significant effect on the serum level in these experiments.