Evidence that bone resorption of young men is not increased by high dietary phosphorus obtained from milk and cheese

Our study consisted of two 10-day periods. In period 1, seven young men (22-31 yrs; average weight of 70 kg) were fed food items providing 800 mg P, 1200 mg Ca, 11.7 MJ and 14.5 g nitrogen. In period two, diet phosphorus was doubled to 1600 mg by addition of cheese and milk. Dietary nitrogen and calcium were equalized for the two periods. Comparison of period 2 with 1 showed that serum intact parathyroid hormone tended to increase suggestive of increased bone turnover, but this possibility was not supported by the bone resorption marker, urinary deoxypyridinoline. High dietary phosphorus increased urinary ammonia N excretion which may play a small role in the mechanism of the hypocalciuric effect of P. We conclude that the high phosphorus intake typical of many diets does not promote bone resorption if the calcium to phosphorus ratio is <1:1.5.