Sargassum soluble dietary fiber alleviates oxidative stress and gut microbiota dysbiosis to prevent inflammatory bowel disease in C57BL/6 mice

BACKGROUND: Fermentation may enhance the bioactivity of Sargassum soluble dietary fiber (SDF). This study investigates the preventive effects of Bifidobacterium longum fermented Sargassum SDF (BL-SDF) against oxidative stress and inflammatory bowel disease (IBD). RESULTS: In vitro, the BL-SDF significantly reduced nitric oxide (NO) production by 16.98-23.04% and reactive oxygen species (ROS) accumulation by 65.30-81.28% in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages, increased superoxide dismutase (SOD) and catalase (CAT) activities, decreased malondialdehyde (MDA), and suppressed prostaglandin E2 (PGE2), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and interleukin-1 beta (IL-1β). In dextran sulfate sodium (DSS)-induced C57BL/6 mice, pre-administration of BL-SDF alleviated weight loss and colonic damage, enhanced antioxidant enzymes activities (SOD, CAT, and glutathione peroxidase (GSH-Px)), and reduced MDA and NO levels in the colon. Additionally, 16S ribosomal RNA (rRNA) sequencing analysis further indicated enrichment of Incertae_Sedis group, Faecalibaculum, and Roseburia, and gas chromatography-mass spectrometry (GC-MS) revealed elevation of acetic acid, propionic acid, butyric acid, and valeric acid (P < 0.05). Concurrently, BL-SDF significantly reduced the expression of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, and interleukin-23 (IL-23). CONCLUSION: BL-SDF alleviates intestinal inflammation by enhancing antioxidant activities and modulating gut microbiota, suggesting that fermented Sargassum SDF may serve as a dietary strategy for preventing inflammatory bowel disease. © 2026 Society of Chemical Industry.