EFFECTS OF DIETARY TOCOPHEROL AND CHOLESTEROL ON THE RATIOS OF TOCOPHEROL TO CHOLESTEROL AND ARGININE TO LYSINE IN RATS

The effects of dietary tocopherol (Toc) (0-10 mg%) and 1% cholesterol (Chol) on the levels of serum Toc, Chol and amino acid were determined using female rats, and the relationships among their levels were studied. Dietary Toc caused an increase in serum Toc (r = 0.66 and r = 0.74, p < 0.01, for the diet containing no and 1% Chol, respectively), which was not significantly affected by a diet supplemented with Chol. There was no significant change in the levels of serum Chol with increases in serum Toe, but supplementing the diet with Chol caused serum Toc to increase together with the level of serum Chol.(r = 0.75, p < 0.001). The ratio of Toc/Chol in serum was dose-dependent on dietary Toc (r = 0.69, p < 0.01). A correlation was also found when the diet was supplemented with Chol (r = 0.79, p < 0.001), but the levels of the Toc/Chol ratio averaged 40% of those found with Chol-free diets. The serum levels of threonine (Thr), lysine (Lys) and arginine (Arg) decreased when Chol was supplemented (p < 0.01, respectively). The ratio of Arg/Lys correlated negatively with the serum levels of Toc and Toc/Chol ratio (r = -0.64, p < 0.01 and r = -0.51, p < 0.05, respectively), but no correlation was found on supplementation of dietary Chol. In all rats, the level of Arg in serum showed a positive correlation to the ratio of Arg/Lys in serum r = 0.84, p < 0.001). These results indicated that the ratio of Toc/Chol in serum, as an indicator of the status of vitamin E nutrition, increased with dietary Toc and decreased with dietary Chol. Dietary Toc and Chol may be involved in the metabolism of Thr, Lys and Arg and may affect the hypocholesterolemic action by changing the ratio of Arg/Lys.