Dietary Fiber from Baijiu Distillers’ Grains Improves Glucose–Lipid Homeostasis via Gut–Liver Metabolic Remodeling

Baijiu distillers’ grains (BDG), a major fermented cereal by-product of baijiu production, represent an underutilized source of structurally modified dietary fiber with potential value for functional food development. Here, we found that BDG-derived dietary fiber (BDG-DF), mainly composed of mannose (34.83 ± 0.38%) and xylose (35.14 ± 0.25%), promoted short-chain fatty acid production during in vitro fermentation, and its fermentation supernatants reduced IL-1β and TNF-α levels and modestly decreased IL-6 production in a Caco-2/HepG2 co-culture model. In T2D mice, BDG-DF improved glucose tolerance, with high-dose BDG-DF reducing the OGTT area under the curve by 12.4% compared with the T2D group, and alleviated hepatic steatosis. These effects were accompanied by enrichment of Akkermansia and Bifidobacterium and remodeling of bile acid profiles. High-dose BDG-DF was also associated with elevated CA and CDCA levels, altered TGR5/GLP-1 signaling, increased hepatic FXR expression, and reduced CYP7A1 expression. Integrated hepatic proteomics and metabolomics further indicated that BDG-DF was associated with changes in unsaturated fatty acid biosynthesis and PPAR-γ-related metabolic signaling. Overall, these findings suggest that BDG-DF may improve glucose–lipid homeostasis in association with gut microbiota and bile acid remodeling and hepatic PPAR-γ-related metabolic signaling.