Vitamin A plays an essential role in the function of retina and is essential for growh and differentiation of epithelial tissue. Vitamin D is supplemented for prevention and cure of nutritional and metabolic rickets and for treatment of hypoparathyroidism. Vitamin E is an antioxidant which preserves essential cellular constituents. Vitamin E plays a role in protecting red blood cells against hemolysis; has protective effects against free radicals on polyunsaturated fatty acids found in cell membranes; plays a role in preventing oxidation of vitamin A and C.