Effect of protein intake on mineral (calcium, magnesium, and phosphorus) balance in Japanese males.

A 26-day balance study was conducted to examine the effect of a high protein diet on calcium, magnesium, and phosphorus utilization in six healthy males (age 20-22 years, body weight 54.0-64.4 kg, body height 165-173 cm). In addition, the effect of physical exercise on calcium, magnesium, and phosphorus balance was also examined. After a 2-day stabilization period, two levels of protein--control (1.0 g/kg of body weight) and high (2.0 g/kg of body weight) protein--diets were given for three 4-day periods at each protein level. During the last 4-day period of each protein level, subjects exercised on a bicycle ergometer for two 1-h periods daily at a load of 1.5 kp., 50 cyc./min. The high protein diet increased urinary calcium and caused a significant negative calcium balance. Magnesium balance tended to be negative in the control diet. There were no significant changes in urinary calcium, magnesium, and phosphorus and also in the calcium, magnesium, and phosphorus balance during physical exercise.