Lowered oral bioaccessibility of cadmium and selenium and associated health risk by co-digestion of rice and vegetables

Abstract

Since foods are not ingested individually, co-digestion, in accordance with human daily diet conditions, should be stressed when assessing elements bioaccessibility and associated health risks. The oral bioaccessibility of cadmium (Cd) and selenium (Se) in 11 types of crops (rice, maize, pakchoi, eggplant, red pepper, towel gourd, kidney bean, soybean, cowpea, sweet potato, and taro) were determined, and the effects of co-digestion of 7 types of rice and vegetables on the bioaccessibility of Cd and Se were evaluated and validated with in vitro PBET method. The underlying mechanism was revealed by observing the surface morphological characteristics of digested substrates, and the exposure risk of Cd and Se were assessed. The results showed that the average bioaccessibility of Cd and Se in 11 types of crops varied from 58.7 % to 39.1 % and 48.4 % to 62.6 % from the gastric phase (GP) to the intestinal phase (IP). Interestingly, co-digestion of rice and vegetables reduced the bioaccessibility of Cd and Se to varying degrees compared to theoretical values. Great reduction in the bioaccessibility of Cd and Se in the GP (16.9–36.4 % and 9.9–23.2 %) than that in the IP (0.2–6.62 % and 0.23–12.3 %) were detected, which was attributed to the rice–vegetable aggregates formed during co-digestion. Rice–vegetable aggregates inhibited the release of Cd and Se, which was more pronounced in the GP than in the IP. Consequently, co-digestion of rice and vegetables reduced the oral exposure to Cd by 35.8 % and to Se by 19.6 %. The areas with higher non-carcinogenic risk of Cd and Se in the study region were reduced by 17 % and 10 %, respectively. Therefore, the role of co-digestion in assessing Cd and Se bioaccessibility and associated health risk cannot be neglected. This study has significant implications for investigating elements bioaccessibility and optimizing associated health risk assessment from a novel perspective.