Dietary prebiotics combined with iron supplementation: A two-pronged approach to reduce rice cadmium bioavailability

While the role of improving gut microbiota and elevating dietary iron (Fe) in reducing cadmium (Cd) oral bioavailability has been assessed, the role of dietary prebiotics combined with Fe in synergistically reducing Cd bioavailability from rice remains underexplored. This study utilized mouse bioassays to investigate the potential of prebiotics alone or combined with Fe in reducing rice Cd bioavailability. In experiments with mice fed Fe-sufficient diets (60.6 μg g^-1) supplemented with Cd, dietary fructooligosaccharides (FOS), galactooligosaccharides (GOS), and inulin (at 5 % w/w) enhanced Fe absorption and reduced Cd uptake. However, in mice consuming Cd-contaminated rice with low Fe content (6.81 μg g^-1), these prebiotics did not increase Fe absorption but lowered mouse kidney Cd by 12.1-20.7 % by improving gut microbiota. Combining 5 % GOS with 100 μg Fe g^-1 in Cd-contaminated rice diets resulted in a 59 % reduction in kidney Cd accumulation, more effective than the reduction with either GOS (8.66 %) or Fe (31.9 %) alone, due to the combination of the role of GOS in improving gut microbiota and enhancing intestinal barrier functions and the role of Fe in lowering intestinal Fe transporters. These findings propose a combined dietary strategy to efficiently mitigate the health risks associated with rice Cd exposure.