Mineral Dietary Supplement To Decrease Cadmium Relative Bioavailability in Rice Based on a Mouse Bioassay

To determine the effectiveness of mineral dietary supplements to modulate cadmium (Cd) exposure, an in vivo mouse bioassay was conducted to determine Cd relative bioavailability (Cd-RBA) in Cd-contaminated rice (0.80 mg Cd kg(-1)) with and without Zn, Fe, or Ca supplements as nitrate or chloride salts. Without mineral supplements, Cd-RBA was 43 +/- 5.3% based on average Cd accumulation in the liver plus kidneys as the end point. Among Ca(NO3)(2), Zn(NO3)(2), and Fe(NO3)(2) supplements, 150-5000 mg kg(-1) Ca was the most effective in reducing rice Cd-RBA by 31-80% to 8.5-29%, while 30-200 mg kg(-1) Zn supplements was ineffective, with Cd-RBA being 33-57%. Low Fe at <40 mg kg(-1) had little impact on rice Cd-RBA (39-47%), while high Fe at 80-200 mg kg(-1) decreased Cd-RBA by 37% to 26-27%. The ineffectiveness of Zn supplements in reducing Cd-RBA was probably due to coinciding 8.3- and 3.1-fold increases in Zn accumulation in mouse kidneys and liver with Zn supplements, while Ca and Fe supplements led to much-smaller increases in Ca and Fe accumulation in mouse tissues (1.3-1.6 fold). In addition, compared to Ca(NO3)(2) supplements, Cd-RBA values determined with. CaCl2 supplements were significantly higher (25-67% versus 8.5-29%), suggesting that chloride enhanced Cd-RBA. Results of this study have important implications for developing effective dietary strategies to reduce dietary Cd exposure and the associated health risks in humans.