Diet and cholesterolemia: V. effects of sulfur-containing amino acids and protein*

• Main Authors: J.C. Seidel, Narindar Nath, A.E. Harper
• Format: Article
• Language: English
• Published: Elsevier 1960-10-01
• Series: Journal of Lipid Research
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520412362

Interrelationships among the effects of dietary protein, sulfur-containing amino acids, and choline on the serum cholesterol concentration of the rat have been studied. Hypercholesterolemia was induced by feeding rats a diet containing cholesterol, cholic acid, and saturated fat. When the diet contained choline, additional casein alleviated the hypercholesterolemia. A similar effect was obtained with a supplement of methionine equal to the amount in the casein. Cystine and cysteine, but not taurine, were as effective as methionine. These and other observations suggest that the serum cholesterol-lowering effect of protein supplements is due largely to the sulfur-containing amino acids they provide. The omission of choline from the diet also alleviated the hypercholesterolemia; but when the choline-free diet was supplemented with either choline or methionine, serum cholesterol concentration increased. A supplement of choline alone caused a much greater rise than a supplement of methionine or combined supplementation with choline and methionine. Thus methionine appears to have two opposing effects on serum cholesterol concentration in rats fed a hypercholesterolemic diet lacking choline: (a) a cholesterol-elevating effect attributable to its ability to spare choline by providing a supply of preformed methyl groups, and (b) a cholesterol-lowering effect common to sulfur-containing amino acids and not, dependent upon the provision of methyl groups.