Zinc status of women with low bone mineral density who receive calcium supplements

We evaluated whether a daily high-dose calcium supplement perturbs the zinc status in 23 postmenopausal women (mean age: 63yr) with low bone mineral density. Plasma and erythrocyte zinc concentrations, plasma bone-specific alkaline phosphatase (BSAP) and 5′-nucleotidase activities, and urinary zinc and calcium excretion were determined first at the end of 4 wk of daily oral calcium (1200 mg) and were measured again at the end of the subsequent 4 wk of daily cosupplementation with calcium (1200 mg) and zinc (30 mg). Mean plasma and erythrocyte zinc concentrations after 4 wk of calcium alone were not significantly different from concentrations after cosupplementation of calcium and zinc. Mean plasma BSAP activities before cosupplementation with zinc was significantly higher than that after zinc (p<0.02), whereas plasma 5′-nucleotidase activities were not affected by zinc supplementation. Urinary zinc excretion slightly, but significantly, increased after the supplementation of zinc (p<0.05), whereas calcium excretion remained similar. Our data indicate that a 4-wk zinc supplementation did not significantly improve zinc status. Although limited by the small sample size and short study duration, our data suggest that a daily calcium dose of 1200 mg had no effect on the zinc status of our subjects.