Linking the fine structural characteristics of cereal β-glucans to their differential protective effects against...

Although cereal β-glucans exert protective effects against experimental colitis, the relationship between their fine structural and physicochemical properties and differential in vivo responses remains unclear. This study directly compared highland barley β-glucan (BBG) and oat β-glucan (OBG), two high-purity mixed-linkage β-(1 → 3)/(1 → 4)-D-glucans, under identical experimental conditions. BBG had a higher cellotriosyl-to-cellotetraosyl (DP3/DP4) ratio than OBG (2.33 vs. 1.51) and a lower weight-average molecular weight. In dextran sulfate sodium (DSS)-induced colitis mice, both β-glucans alleviated clinical signs of disease, while BBG showed greater protection at the tissue and biochemical levels. BBG preserved colon length at 4.88 cm, compared with 4.46 cm for OBG. It reduced myeloperoxidase activity, nitric oxide, and malondialdehyde levels to 1226 U g^-1, 0.42 μmol g^-1, and 78.8 nmol mg^-1, respectively, and fully restored Claudin-1 expression. BBG was also associated with enrichment of Ligilactobacillus, Limosilactobacillus, Romboutsia, and Turicibacter and suppression of Escherichia-Shigella. Fecal metabolomics showed higher levels of selected indole derivatives and taurine-conjugated bile acids, accompanied by lower uric acid and prostaglandin-related inflammatory metabolites. These in vivo differences were accompanied by distinct physicochemical behaviors. BBG showed faster self-aggregation, with a shorter lag time than OBG (112.9 vs. 256.0 min), accompanied by a markedly higher storage modulus (360 vs. 66 Pa). BBG also showed stronger intestinal-phase reassembly under simulated gastrointestinal conditions, approximately threefold greater bile acid retention during dynamic dialysis, and higher DPPH radical-scavenging activity (11.8% vs. 4.8%). Overall, the differential intestinal responses to BBG and OBG were accompanied by distinct physicochemical, microbial, and metabolic profiles, supporting a potential aggregation between cereal β-glucan fine structure, supramolecular behavior, and protective effects against colitis.