Effects of high dietary contents of calcium and phosphorus on mineral metabolism and growth of vitamin D-deficient suckling and weaned rats.

We have tested the hypothesis that normalization of the plasma calcium (Ca) and phosphorus (P) concentrations by dietary means in vitamin D-deficient rat pups will prevent rickets. From day 6 of pregnancy rats were given a vitamin D-free diet containing 1.6% Ca and 1.4% P (-D 1.6) which normalized plasma Ca during lactation. Pups weaned from these mothers, and continuing on the -D 1.6 diet until 56 days of age, had a mean plasma Ca value of 8.6 +/- 0.2 mg/dl and were not significantly different from pups fed a vitamin D-replete diet with 0.4% Ca and 0.4% P in the following parameters: body weight (mean +/- SE for -D 1.6 rats: 197 +/- 4 g), percent bone ash (53 +/- 0.5), and tibia epiphyseal cartilage width (385 +/- 26 micron). In contrast, pups consuming the vitamin D-free diet with 0.4% Ca and 0.4% P had plasma Ca of 4.9 +/- 0.2 mg/dl, body weight of 156 +/- 4 g, reduced bone ash (45 +/- 0.5%) and abnormally wide epiphyseal cartilage (727 +/- 113 micron). Thus, elevating the plasma Ca level of vitamin D-deficient rat pups by dietary means can normalize body weight, epiphyseal cartilage width and bone mineral content.