Nutritional status affects the bioaccessibility and speciation of arsenic from soils in a simulator of the human intestinal microbial ecosystem

Highlights: • The effects of four nutritional states on arsenic bioaccessibility were different. • In the colon phase, As bioaccessibility was observably enhanced by protein powder. • The order of As methylation percentages was protein powder > vitamin C > fasted state > glucose (except S2). • Large amounts of MMA^V were observed with the addition of protein powder in the colon digest. • Glucose enhanced the reduction of As(V) in the colon digest. Arsenic (As) is a highly toxic contaminant in food and soil. In this study, we investigated the effects of four nutritional states (including a fed state with vitamin C, a fed state with protein powder, a fed state with glucose and a fasted state) on the variability of soil As bioaccessibility and biotransformation using the physiologically based extraction test (PBET) combined with a simulator of the human intestinal microbial ecosystem model (SHIME). The results indicated that the vitamin C and protein powder increased As bioaccessibility in gastric digests. In the colon phase, As bioaccessibility was observably enhanced by protein powder, and it varied under the vitamin C and glucose conditions. Additionally, the order of As methylation percentages in the four nutritional states was protein powder > vitamin C > fasted state > glucose (except S2); As bioaccessibility increased 1.3–13.7% and 15.8–35.4% in treatments of the vitamin C and protein powder, respectively. Meanwhile, large amounts of monomethylarsonic acid (MMA^V) were observed in the colon digest in the protein powder condition. In contrast, As methylation was significantly decreased with the addition of glucose, with a decline of 25.9–45.5%. Additionally, glucose enhanced the reduction of As(V). Therefore, nutritional status is a crucial parameter for the prediction of bioaccessibility and speciation of As when assessing health risks from As following oral exposure.