Comparative analysis of dietary fiber impact on bile acid metabolism and gut microbiota composition in mice

Dietary fiber is essential for health but remains under-consumed in Western diets. Fiber types differ in their physicochemical properties, which influence gastrointestinal function, bile acid (BA) metabolism, and gut microbiota composition. C57Bl/6 mice were fed control or 10% (w/w) fiber diets containing cellulose, chitin, resistant starch, pectin, inulin, β-glucan, psyllium, dextrin, or raffinose. All fibers reduced bacterial diversity, while most increased <i>Akkermansia muciniphila</i> abundance. Cellulose/chitin and inulin/β-glucan/raffinose formed distinct microbiome clusters. <i>Rikenellaceae</i> correlated positively with taurine-conjugated BAs levels. BA concentrations were reduced across tissues. Taurine conjugates showed inverse liver-intestine distribution. Inulin and β-glucan resulted in the highest taurine conjugate levels and reduced intestinal taurine-conjugated BAs concentrations, suggesting enhanced bile salt hydrolase (BSH) activity. Resistant starch had a minimal effect. Psyllium most strongly impacted BA- and taurine-related gene expression, cecum size and weight loss. Dietary fibers distinctly modulate BA metabolism and gut microbiota, with implications for metabolic health and targeted therapies.