Fermented milk derived from a novel probiotic strain enhances digestive function and attenuates dextran sulfate sodium-induced colitis via the microbiota-metabolite-immune axis.

Probiotic-fermented dairy products are increasingly recognized for their dual role in nutrient optimization and disease prevention. This study investigated the mechanisms by which Bifidobacterium animalis subsp. lactis Probio-M8 fermented milk enhances digestive efficiency and protects against dextran sulfate sodium-induced colitis in rats. FM8 supplementation promoted weight gain without excessive adipogenesis, elevated leptin levels, and amplified sucrase, lactase, aminopeptidase, and lipase activities, outperforming conventional fermented milk. Metagenomic analysis revealed microbial restructuring with Corynebacterium glutamicum and Bifidobacterium animalis enrichment, and increased short-chain fatty acids.Untargeted metabolomics identified FM8-responsive metabolites, including p-hydroxybenzaldehyde and indole-3-carboxaldehyde, linked to anti-inflammatory pathways. In dextran sulfate sodium-challenged rats, FM8 pre-administration attenuated colitis severity by reducing disease activity index scores, normalizing colon histology, and suppressing interleukin (IL)-6 and IL-17 while elevating IL-10 and IL-22. Mechanistically, FM8 enriched Bifidobacterium animalis and butyrate levels, which inversely correlated with mucosal injury and pro-inflammatory cytokines. These findings demonstrate that FM8 enhances gastrointestinal health through tripartite microbiota-metabolite-immune interactions, highlighting its functional potential for metabolic optimization and colitis prevention.