Different oat bran dietary levels modulate diabetic dyslipidemia: gut microbiota-metabolome associations in HFD/STZ-induced rats

This study investigates responses associated with two oat bran dietary levels (15% and 30%, w /w) in diabetic dyslipidemia. High-fat diet/streptozotocin-induced diabetic rats received 15% oat bran (OBL) or 30% oat bran (OBH) dietary formulations for six weeks, followed by physiological, shotgun metagenomic, and untargeted metabolomic analyses. Both formulations improved glucose tolerance, modulated serum lipid profiles, and attenuated systemic inflammatory and oxidative-stress responses, accompanied by increased intestinal barrier-related markers. Oat bran supplementation reshaped HFD/STZ-associated gut microbial dysbiosis. Metabolomic analysis revealed distinct response patterns between OBL and OBH groups: OBL was primarily associated with antioxidant-related responses, whereas OBH showed additional exploratory pathway-level associations involving sphingolipid metabolism, glycerophospholipid metabolism, and bile secretion. Furthermore, Prevotella and Akkermansia were identified as highly connected network taxa whose abundances were associated with metabolic and barrier-related parameters. Collectively, oat bran supplementation was associated with improved metabolic outcomes and concurrent changes in gut microbial, serum metabolic, intestinal barrier-related, and systemic inflammatory profiles, supporting its potential as a dietary strategy for metabolic regulation.