Mechanisms and health implications of calcium in reducing arsenic bioaccessibility via in vitro gastrointestinal digestion.

Accidental oral ingestion is an important route of exposure to arsenic (As) containing soil and dust. However, the mechanism by which As bioaccessibility is reduced by in vitro digestion of calcium (Ca) remains unknown. In this study, we investigated the effect of Ca intake on the behaviors of As release from simulated gastrointestinal bio-fluids. The results showed that the bioaccessibility of As(III) and As(V) in simulated gastric bio-fluid was reduced by 43.68 % and 37.22 % (p < 0.05), respectively, when the dosage of Ca addition was 10 g/L after 1 h. The bioaccessibility of As(III) and As(V) in simulated intestinal bio-fluids was reduced by 76.13 % and 69.16 % (p < 0.05), respectively, after 8 h. Ca effectively reduced the As bioaccessibility in simulated gastrointestinal bio-fluid, particularly preprandial Ca intake reduced the risk better than postprandial. Ca can achieve As immobilization through electrostatic attraction, surface complexation and other pathways. Ca intake reduces As bioaccessibility through the formation of Fe-As-Ca ternary complexes. These results suggests that Ca-rich supplements could be an effective nutritional strategy to reduce As toxicity. This study deepens our understanding about how Ca interacts with As-containing minerals in simulated gastrointestinal bio-fluids and provides a nutritional strategy to mitigate the health risk of accidental As ingestion.