[Long-term effects of various levels of dietary proteins as well as starch and sucrose as dietary carbohydrates on lipoprotein metabolism in the rat].

UNLABELLED

The repeatedly reported effect of proteins on lipoprotein metabolism leaves the question if this is caused mainly by the amount of amino acid composition of the protein itself, by the accompanying fat of cholesterol content, or by the contemporary predominant kind of carbohydrate in the diet. The conducted experiments with male rats, feeding them in 6 groups of 20 animals for one year semipurified, cholesterol-free diets with constantly 40 (J-)% fat in all diets, 13% (I), 20% (II, III, IV) or 40% (V, VI) protein and complementary carbohydrates (50% starch, 50% sucrose). III received sucrose only, IV starch only. VI was given additionally 0.8% arginine (arg). Rats on 40% protein exhibited higher total plasma cholesterol levels in comparison to 13% protein, HDL values were nearly identical in I, II, III, IV, and increased in V and VI. LDL was increased in V, compared to all other groups.

CONCLUSION

The level of dietary protein alone may influence amount and distribution of lipoproteins in rats. LDL may be decreased by addition of arg, HDL remains unchanged. The type of carbohydrate had no influence on HDL or LDL on conditions of our experiment, whereas earlier experiments showed elevation of LDL values with sucrose in comparison to starch if cholesterol was present in the diet.