Variability of chromium bioaccessibility and speciation in vegetables: The influence of in vitro methods, gut microbiota and vegetable species

There is limited research concentrating on the effects of gut microbiota on the bioaccessibility and speciation of chromium (Cr) in vegetables. In this study, the physiologically based extraction test (PBET) and the unified BARGE method (UBM), were combined with the simulator of human intestinal microbial ecosystems (SHIME) to determine the bioaccessibility and speciation of Cr from vegetables. The results showed that the Cr bioaccessibility was the highest in the gastric phase. The Cr bioaccessibility from the water spinach was the highest, and was 1.6-3.4 and 1.1-1.8 times that of leaf lettuce and celery, respectively. The Cr bioaccessibilities of the UBM method were slightly greater than those of the PBET method. Additionally, the gut microbiota increased the Cr bioaccessibility and reduced more toxic Cr(VI) to less toxic Cr(III) from vegetables. Therefore, our study reveals the possible health risks of consuming Cr-contaminated vegetables based on the bioaccessibility and speciation of Cr.