Impact of Soybean Polysaccharides on Microbial Composition and Metabolic Output in an In Vitro Model of the Aging Gut

This study explored soybean polysaccharide (SP) for modulating aging gut dysregulation. SP showed dose-dependent antioxidant effects, as demonstrated by its ABTS radical scavenging, DPPH radical scavenging, hydroxyl radical scavenging, and reducing power capabilities. Given the challenges of dysphagia, susceptibility to digestive impairment, and ethical concerns with invasive intervention in aging rodents, we used an in vitro simulated colonic fermentation approach with feces from aged mice to establish an aging gut model. In this model, SP promoted short-chain fatty acid (SCFA) production, acidified the colonic lumen, and rebalanced gut microbiota. Specifically, SP increased the abundance of probiotic genera while reducing pathogenic Escherichia-Shigella in Aging groups. Metabolomics revealed that SP modulated the metabolite spectrum, enriching oligosaccharides, which positively correlated with probiotic growth and SCFA biosynthesis. These findings provide in vitro evidence that SP acts as a versatile functional ingredient with potential prebiotic-like effects, which may help address multi-faceted aging-related challenges, including oxidative stress, microbial dysbiosis, and decline in beneficial metabolites, rather than direct evidence of improved aging gut health.