Comparison of the effects of calcium loading with calcium citrate or calcium carbonate on bone turnover in postmenopausal women: reply

Excerpt

We have two serious concerns about the publication of the biomarker data from Kenny et al. [1]. First, while Kenny et al. reconfirm our findings of equivalent bioavailability of calcium from Os-Cal and Citracal [2,3] and also reconfirm our findings of the physiological response to supplementation with calcium carbonate and vitamin D in Os-Cal, i.e. a significant decrease in PTH following supplementation, we can find no biologically plausible explanation for the biomarker data reported in the calcium carbonate arm of this study. Since the decrease in PTH is required for the reduction in resorption markers, and several published studies cited by Kenny et al. have shown that calcium carbonate does reduce resorption biomarkers, we have serious concerns with the Kenny et al. paper. …