|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1995 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Osteoporosis is a disease characterised by low bone mass excessive loss of minerals and protein contents in bone. For the prevention of osteoporosis, factors affecting lifestyle such as diet or physical activity are important. The effects of protein intake, dietary protein of different sources and voluntary running exercise on mineral utilization by the body and bone metabolism in the femur were investigated in growing male rats and adult ovaritectomized (OVX) rats. The apparent intestinal absorption of Ca, P,and Mg and their retention by the body increased linearly with dietary concentrations of 5,10,20, and 30% casein diet in growing male rats. Hence, dietary protein deprivation resulted in slow bone growth and weak bone strength. These findings indicated that protein intake during the crucial years of peak bone mass development is important for the prevention of osteoporosis.
Although Ca excretion in urine is known to be directly correlated with the level of dietary protein intake, t
he effects of excess dietary protein intake on bone metabolism is nuclear. The effects of high protein diets of different sources, 25% casein, 50% casein, 50% soy protein isolate (SPI), 25% casein+25% collagen peptide (LCP), and 25% SPI+25%LCP,on bone metabolism was studied in OVX rats for 12 weeks. Exercise groups were set up in each of those groups that were fed diets cotaining LCP.The different protein sources and exercise had no effect on food intake, body fat, and final body weight. Although increasing the level of dietary protein from 25% to 50% in OVX rats caused a tenfold increase in urinary Ca, there were no differences in Ca retention and weight, Ca content, and breaking force of femur. Weight, Ca, and Mg contents of the femur in the groups fed on diet containing LCP were significantly higher than those in the groups fed on casein and SPI.The breaking force of the femur and humerus in these groups were higher than those in the groups fed on casein and SPI.
These results suggest that although excess protein intake exerted a significant calciuretic effect, in rats, the amount of Ca excretion in the urine was very small and has little small effect on bone metabolism. Collagen peptide has some effect on bone metabolism. Less