The Relation of Vitamin D to Deposition of Calcium in Bone. ∗

Abstract

Quantitative studies in our laboratory 1 have shown that when the food of the growing animal (rat) includes a liberal allowance of vitamin D and a constant supply of phosphorus (0.42%), the calcium content of the bodies as determined at intervals during the period of growth is markedly influenced by the calcium content of the food, as varied in these experiments from 0.16 to 0.50% of calcium in the dry food mixture.

In the present experiments we find further, that in rats receiving a basal diet containing a generous allowance of calcium and phosphorus in good proportions (calcium, 0.74%; phosphorus, 0.58%) but with the vitamin D supply restricted practically to a bodily store acquired by 21 to 28 days of age, the growing body has at a given age about the same calcium content as has been acquired by similar animals which received 0.32% calcium, 0.42% phosphorus, and a liberal supply of vitamin D.

The calcium content of the femurs of rats which had been kept from the age of 21 or 28 days to the age of 56 days on the vitamin-D-deficient diet which we have previously described 2 is about twice as high as in otherwise similar rats fed the high-calcium rickets-producing diet of Steenbock (No. 2965) for the same length of time.

Our rats have not had rickets according to the criterion of the “line” test, yet the deposition of calcium in their growing bones has been influenced by the vitamin D content of the food, even though the percentages of calcium and phosphorus in the dry food mixtures were favorable and uniform. Graded amounts of vitamin D supplied in the form of whole (summer) milk powder induced graded increments in calcification up to what appears to be the maximum potential level.