Assessment of effectiveness of oral administration of collagen peptide on bone metabolism in growing and mature rats

The purpose of this study was to examine the effectiveness of collagen peptide intake on bone metabolism in growing (G) and calcium-deficient mature (M) rats. As for the dosages used, they were amounts equal to the recommended supplements for humans (0.166 g/kg body weight (BW) per day: Coll-1G and Coll-1M groups), 10-fold higher (1.66 g/kg BW per day: Coll-10G and Coll-10M groups), and 100-fold higher (16.6 g/kg BW per day: Coll-100G group). In growing male rats, bone mineral density (BMD) of the femur in the Coll-100G group was significantly higher than that in the other groups after the 4-week experimental period. On the other hand, kidneys in the rats from the Coll-100G group exhibited hypertrophy. To examine the effects of collagen peptide on bone metabolism in a calcium-deficient status, mature female rats were fed a 0.01% Ca diet for 9 weeks and then fed a diet with 0.2% calcium with or without collagen peptide (control, Coll-1M, and Coll-10M groups) or a 0.5% calcium diet (normal Ca) for 8 weeks. BMD of the whole femur in the Coll-10M group was significantly higher than that in the control and Coll-1M groups, and the level was similar to that in the normal Ca group. BMD of the lumbar spine in the Coll-10M group was significantly higher than their baseline value, as well as being significantly higher than that in the control and Coll-1M groups. These results suggest that orally administered collagen peptide may provide beneficial effects on bone metabolism, especially in the calcium-deficient condition, without obvious undesirable effects.