Effect of Dietary Vitamin D and Protein on Free Amino Acids and Lipids in Selected Rat Tissues

Abstract
Weanling male rats were fed for 6 weeks vitamin D-deficient rations which contained 2 levels of protein with varying levels of supplemental calciferol. Vitamin D decreased the concentration of free lysine but had no apparent effect on free methionine or valine in plasma. Increasing the level of the vitamin significantly increased the concentration of cholesterol and total lipids in liver of rats fed 9% of casein but had no significant effect on that of animals fed 18% of casein. Increasing the protein intake decreased the level of lipids in liver of animals fed no vitamin D supplement or either level of the supplementary vitamin. The results suggested that amino acid-calciferol ratio may be important in lipid metabolism.