The bioavailability of calcium in the form of pyruvate, carbonate, citrate-malate in healthy postmenopausal women

There is an ongoing controversy respecting calcium supplementation and its role in osteoporosis treatment and prevention. Ca can be present in different forms that are likely to vary in their chemical properties and bioavailability. This is the first study to investigate the bioavailability of calcium pyruvate (CaPyr) and to compare it with calcium citrate malate (CaCitrMalt) and calcium carbonate (CaCarb).We performed a double-blind, four-arm, randomized, placebo-controlled trial (crossover design with 14-day washout) in which 1 g of Ca in each of these forms was administrated orally to 12 healthy postmenopausal women fasted prior to intervention. The greatest increase in serum Ca content was observed within the first 180 min although no statistically significant difference was found in the area under the plasma concentration curve between the studied supplement groups. The urinary Ca content in the 0- to 12-h interval increased after CaCitrMalt and CaPyr administration with the greatest values observed for the former. All the studied formulas decreased the intact parathyroid hormone level in serum although the greatest change was observed for CaPyr and CaCarb. The administration of CaPyr induced gastrointestinal side effects, dyspepsia and diarrhea in 16.6 % of the studied individuals. No serious adverse events were noted. CaPyr demonstrates both a promising source of Ca and a potential for use in osteoporosis prevention. Further investigations should focus on the long-term dietary effects of CaPyr supplementation to assess its safety and potential beneficial effect on human Ca turnover.