Work

Gastrointestinal transit time shapes mouse gut microbiome responses to dietary fiber content and regulates satiety hormones

Year: 2026

Type: article

Abstract: Intestinal transit time (TT) influences gut microbiota composition and metabolism, with longer TT favoring proteolytic and shorter TT saccharolytic fermentation. How diet modulates these associations remains unclear. We examined the effects of dietary fiber and TT on microbial metabolism and host responses in mice (n=48) fed low-, medium-, or high-fiber diets, then treated with saline or loperamide for one week to prolong TT. Fiber increased alpha diversity, while loperamide treatment reduced it. The gut microbiome clustered by diet and loperamide treatment. Higher fiber intake increased intestinal acetate and butyrate levels and lowered branched-chain fatty acids (BCFAs), urinary/serum p-cresol sulfate, and urinary phenylacetyl glycine. Loperamide induced fiber-dependent metabolite shifts: reducing cecal acetate in low/medium-fiber groups, decreasing acetate and butyrate in high-fiber proximal colon, increasing circulating BCFAs in medium/high-fiber groups, and increasing circulating indoxyl sulfate in medium-fiber mice. Portal vein GLP-1 and PYY increased with loperamide treatment in low/medium-fiber groups. These findings demonstrate that TT modulates fiber effects on the gut microbiome and influences satiety hormone secretion.

Source: Gut Microbiology

DOI: 10.1016/j.gutmic.2026.100011