The Effect of Phosphorus on the Biological Estimation of Vitamin D Activity

Abstract

It has been found under conditions commonly employed for the biological estimations of vitamin D that phosphorus added to the vitamin supplement greatly enhances its apparent potency. The equivalent healing is found to be proportional to the product of the vitamin by the phosphrous fed. For example, 4.0 mg. of phosphorus per day for 8 days (as sodium glycerophosphate) enhances the potency of crystalline vitamin D₂ by a factor of 3.4 times. All phosphorus containing compounds do not possess the same enhancement factor. The significance of this relationship in the estimation of the antirachitic potency of phosphorus containing foods (such as milk) is pointed out.