Variation in Bioaccessibility of Cadmium and Lead in Wheat Genotypes and its Correlation with Nutrient Composition

Abstract

Excessive cadmium (Cd) and lead (Pb) accumulation in wheat grains poses a serious threat to human health. Screening and utilizing wheat cultivars with low concentrations and bioaccessibility of Cd and Pb are effective solutions to reducing health risks from exposure to Cd and Pb in wheat. Here, we conducted a field experiment using 11 wheat cultivars, investigated the genotypic differences in Cd and Pb bioaccessibility in grains, and assessed related human health risks. The relationship between Cd and Pb bioaccessibility and concentrations of mineral elements, phytate, methionine, and cysteine in grains was examined. Significant differences in concentrations and bioaccessibility of Cd and Pb were observed among the 11 cultivars. Cd and Pb concentrations were 0.14–0.56 mg kg-1 and 0.08–0.39 mg kg-1, respectively. Cd and Pb bioaccessibility percentages in the intestinal phase were 5.28%–57.43% and 0.72%–8.74%, respectively. Based on bioaccessible Cd and Pb concentrations, the bioaccessible hazard index (HIB) values of four cultivars were lower than 1, implying relatively low health risks. Among them, Shannong16 had the lowest concentrations of Cd and Pb in grains and was selected as a safe wheat cultivar with low health risk. Among the tested nutrient components, concentrations of Ca and Phytate were significantly negatively correlated with Cd and Pb bioaccessibility, while concentrations of methionine and cysteine showed significant positive correlations with Cd and Pb bioaccessibility. The results of stepwise regression analysis showed that Ca, phytate, and methionine were the key factors affecting Cd and Pb bioaccessibility. These results indicate that screening safe wheat cultivars with low health risks based on bioaccessibility data is helpful in healthy grain production in farmland polluted by Cd and Pb. These findings contribute to a better understanding of the effects of nutrient components on Cd and Pb bioaccessibility in wheat grains.

Keywords: Cadmium, Lead, Bioaccessibility, Wheat, Genotypic differences, Phytate