Calcium-mediated reduction of cadmium bioaccessibility and bioavailability in rice: Insights for health risk mitigation

Dietary cadmium (Cd) exposure poses a significant health risk to high-rice-consumers, and calcium (Ca) has been identified as a key inhibitor of gastrointestinal Cd absorption. This study used IVG (in vitro gastrointestinal)/PBET (physiologically based extraction test) digestion models and Caco-2 assays to evaluate Ca’s regulation of rice Cd bioaccessibility (BAC)/bioavailability (BAV), assess Cd removal by KCM (1:2)/RCM (1:4) cooking, and conduct THQ health risk assessments. Key findings: rice Cd BAC was higher in IVG than PBET (consistent with soil Cd research, conflicting with some rice studies); PBET had higher predictive accuracy (notably at 0.3 mg/kg Cd) and is a viable BAC assessment alternative. Cd BAV rose with Cd concentration; high Ca supplementation reduced Cd BAC (marked at 0.2–0.3 mg/kg Cd) and BAV (56.42% reduction at 0.1 mg/kg Cd, most effective). Health risk assessments confirmed BAC data integration or increased dietary Ca supplementation effectively mitigates Cd-related risks (especially for rice with 0.1–0.2 mg/kg Cd), while 1:4 RCM cooking achieves efficient Cd removal. This study highlights in vitro digestion-cell assay combination for Cd risk evaluation, identifies dietary Ca supplementation/optimised cooking as practical mitigation strategies, advocates standardised method-INFOGEST to boost cross-study comparability, and provides critical insights for protecting high rice consumers. • Maximal Cd BAC reductions at 0.2 mg/kg and 0.3 mg/kg for PBET & IVG • Ca exerted a more pronounced reduction on Cd BAV at lower Cd levels • PBET/Caco-2 models are validated for assessing Cd BAC/BAV • Future Cd BAC studies should adopt standardised methods like INFOGEST