ABSTRACT
Abnormal metabolism in blood lipids is unquestionably the most important factor in the development of atherosclerosis. Among abnormalities in the lipid metabolism, hypercholesterolemia has been recognized as being responsible for the development of atherosclerosis since Anitschkow and Chalatow demonstrated this in 1913 by feeding crystalline cholesterol to rabbits. This chapter discusses the relationship between dietary amino acids and endogenous hypercholesterolemia as well as normocholesterolemia. Since dietary-supplemented sulfur-containing amino acids and glycine affect the serum cholesterol levels depending upon the disease models used, the effects of dietary amino acids on cholesterolemia should be estimated in each individual disease model. The hypercholesterolemic effect of methionine in 10% casein-diet-fed euthyroid rats was lost in the hypothyroid state, whereas the hypocholesterolemic effect of methionine in euthyroid rats fed the 20% casein diet occurred in the hypothyroid state. The methionine effects may be mediated by thyroid hormones on feeding the low casein diet but not on feeding the diet with an adequate level of casein.
