Calcium Metabolism and Bone Formation in Rats Fed a High Protein Diet

Abstract

The effects of a high protein diet on Ca matabolism and bone formation were evaluated in growing rats. Urinary Ca excretion was increased 3 days after the ingestion of the high protein diet and apparent Ca absorption tended to be decreased in rats fed the high protein diet. As the result, decreased serum Ca concentration was observed in the high protein diet group. Bone formation was examined by endochondral bone forming system using demineralized bone powder. Fourteen days after the implantation of demineralized bone powder, it was observed that an active bone remodeling was induced by osteoblasts and osteoclasts in the control group. By contrast, a greater part of cartilage was found in the high protein diet group, which indicated the inhibition or the retardation of bone formation, without affecting the values of biochemical parameters. A reduced Ca availability at the site of cartilage calcification might be thought to impair bone formation.