Calcium supplementation is a widely recognised strategy for realising adequate calcium intake. Recent studies revealed comparable bioavailability of all available calcium salts. Freshwater crayfish rely on amorphous calcium carbonate (ACC), a thermodynamically instable and very rare biomineralised polymorph of calcium carbonate, characterised by distinctive nanometric spherules (in contrast to the microsized crystals found in other polymorphs), as the main mineral in the exoskeleton and in their temporary storage organ, the gastrolith. Inspired by the crayfish model, we have previously shown an increase in calcium bioavailability, bone absorption and retention in rats administered with synthetic stable ACC compared with crystalline calcium carbonate (CCC). Recently, we showed ACCs beneficial effects on bone loss prevention, bone formation and bone mechanical strength maintenance in an ovariectomy rat model. In this randomised double-blind crossover trial we compared the fractional calcium absorption (FCA) of ACC and CCC in 13 early postmenopausal women, using the dual stable isotope technique. The results of this study showed that FCA of ACC was 2 times greater than that of CCC on average. One subject who was administered with calcium capsules in a fasted state presented X4.6 increase in ACC/CCC relative FCA, suggesting that the unique nanometric amorphous nature of ACC makes it independent on gastric acidity for adequate absorption. This study further highlights the superior absorption of synthetic stable ACC over other commercially available calcium supplements, suggesting its preferable effectiveness for prevention of postmenopausal-related bone loss and as a potential treatment for calcium malabsorption-related disorders or conditions.
Disclosure: The authors declared no competing interests. This work was sponsored by Amorphical LTD.