[The effect of lipid level lowering diets on bile lipids and plasma lipoproteins in normal persons]

The effects of two fat-modified diets, one rich in polyunsaturated and the other in oleic acids, were studied in 10 healthy young males with regard to bile lipid composition, plasma lipids and lipoproteins. The two experimental diets were given for 2 weeks each and findings compared with those from the subject's normal diet. The fat-modified diets had marked but comparable effects on plasma total cholesterol (decreases by 23% and 16% respectively), on LDL-cholesterol (decreases by 27% and 17% respectively) and on HDL-cholesterol (decreases by 26% and 27% respectively). HDL apolipoproteins A-I and A-II were unaffected. Therefore, the apo A-I/HDL-cholesterol and apo A-II/HDL-cholesterol ratios significantly increased. The "lithogenic index" as a measure for the relationship of cholesterol to bile acids and phospholipids, and thus for the solubility of cholesterol in gallbladder bile, was not affected by the lipid lowering diets, which therefore should not increase the risk of cholelithiasis.