Medium-chain inulin enhances systemic immunity and intestinal health by modulating the gut microbiota and metabolome in C57BL/6 mice

Abstract This study investigated the impact of medium-chain inulin on systemic immunity and its mechanisms. Sixty healthy male C57BL/6 mice, three weeks old, were divided into five groups of twelve, housed in three cages each. They were fed a normal diet, with variations including 0%, 1%, 3%, 5%, or 7% medium-chain inulin. The study found that inulin supplementation at 3% or higher reduced serum cholesterol, triglycerides, and LDL levels, while increasing IgG and IgA levels. Inulin also enhanced intestinal health, as indicated by a reduction in crypt depth, and increases in villus height and villus-to-crypt ratio. Moreover, inulin, particularly at 3% or higher, boosted populations of specific gut bacteria like Candidatus_Saccharimonas, Prevotellaceae_UCG-001, Bifidobacterium, Bacteroides, and Dubosiella. It also raised levels of certain metabolites such as stearamide, fatty acid-hydroxy fatty acids (4:0/18:0), L-malate, orotic acid, and bilirubin. Notably, these inulin-induced changes in microbes and metabolites were positively associated with improved immune and intestinal health. Overall, the study concluded that dietary inulin supplementation above 3% enhances systemic immunity and intestinal health, primarily by promoting beneficial gut bacteria and metabolites.