Effects of Dietary Selenium Supplementation on Intestinal Barrier and Immune Responses Associated with Its Modulation of Gut Microbiota

Variations in selenium (Se) intake have been reported to affect the barrier function and immune responses in the gut. Previous studies mainly focused on the role of Se itself or its metabolites, while the influences of the Se-intake-related microbiota on gut health were not thoroughly studied. This study compared the effects of different dietary Se supplementation (Se-deficient, Se-adequate, and Se-supranutritional) on the gut microbiota of mice. Fecal microbiota transplantation (FMT) was further conducted to bypass the effect of Se itself and provided direct evidence that the effects of dietary Se supplementation on the intestinal barrier and immune responses are associated with its modulation of the gut microbiota. Deficient Se supplementation can result in a phenotype of gut microbiota that is more susceptible to dextran sulfate sodium (DSS)-induced colitis and Salmonella typhimurium infection. Sufficient or supranutritional Se intake can optimize the gut microbiota for protection against these intestinal dysfunctions.