Increase in bone mineral density through oral administration of shark gelatin to ovariectomized rats

The incidence of bovine spongiform encephalopathy has resulted in marine collagen hydrolysate (low-molecular-weight gelatin) being sold as supplements and cosmetics in Japan. Shark skin collagen is one of the important sources of marine collagen. We examined the effect of shark skin gelatin in an osteoporosis model animal. Shark skin gelatin was orally administered to ovariectomized rats with a low-protein diet. Bone mineral density of the right femur was measured. Collagen and glycosaminoglycan in the tibial end were extracted and analyzed by western blotting and cellulose acetate membrane electrophoresis, respectively. Administering collagen to the ovariectomized rats resulted in the bone mineral density of the femur epiphysis being higher than that in the sham-operated rats. The contents of type I collagen and glycosaminoglycan in the epiphysis were increased by administering shark skin gelatin. These results indicated that shark skin gelatin would be useful as a dietary supplement for treating osteoporosis.