Oral calcium suppresses biochemical markers of bone resorption in normal men

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Abstract
Calcium supplementation decreases bone resorption and retards bone loss in women. There is little information about the effects of calcium supplementation in men. The effects of a 1-g oral calcium load at 0900 on bone-related biochemical variables were evaluated in 13 normal men (aged 51–70 y). Calcium administration was associated with increases in plasma ionized calcium (P < 0.001) and urinary calcium (P < 0.001), and a decrease in plasma parathyroid hormone (P < 0.001). There was a nonsignificant trend (r = −0.47, P = 0.11) for the decrease in plasma parathyroid hormone to be related to radiocalcium absorption. After the calcium load there were decreases in the urinary hydroxyproline-creatinine ratio from 11 ± 1.1 to 7.9 ± 0.6 (P < 0.01), the urinary deoxypyridinoline-creatinine ratio from 14.0 ± 1.8 to 10.1 ± 0.9 (P < 0.05), and the urinary pyridinoline-creatinine ratio from 52 ± 5 to 40 ± 3 (P < 0.01) between baseline and 6 h. There was no change in plasma osteocalcin. These observations indicate that a 1-g calcium load suppresses biochemical markers of bone resorption for ≥ 6 h in normal men and support the concept that calcium supplementation may be useful in the prevention of bone loss in men.