Metabonomics combined with 16S rRNA sequencing to elucidate the hypoglycemic effect of dietary fiber from tea residues

Tea residues are rich in dietary fiber, which possesses excellent physicochemical and functional properties in vitro. However, the hypoglycemic effect and mechanism of dietary fiber from tea residues are not clear. The study aimed to investigate the potential hypoglycemic effect of dietary fiber obtained from tea residues fermentation (TRDF) and reveal its related mechanisms of action in terms of both intestinal flora and metabolomics. The type 2 diabetes (T2D) rat model induced by high-fat diet and streptozotocin injection was applied in this study. Four weeks of TRDF intervention could remarkably ameliorate hyperglycemia, severe oxidative stress and insulin resistance of diabetic rats. Additionally, there was a significant increase of short chain fatty acids (SCFAs) concentrations in feces of diabetic rats after TRDF intervention. Furthermore, TRDF played a positive role in relieving intestinal microbiota dysbiosis by enriching beneficial bacteria (S24-7 and Prevotellaceae) and inhibiting harmful bacteria (Desulfovibrionaceae and Clostridiaceae). Metabolomic analysis showed that TRDF improved the amino acid metabolism and citrate cycle. The study elaborated on the hypoglycemic effect and potential mechanisms of TRDF through multiple pathways of gut microbiota and metabolites, which could provide theoretical basis for TRDF as a dietary supplement to manage T2D.