Heat-inactivated probiotic-fermented tamarind pulp alleviates constipation by modulating gut tryptophan catabolism and the AhR NLRP3 axis

Introduction Constipation is a common gastrointestinal disorder with gut dysbiosis, and existing laxatives often have limitations, necessitating the development of safer and more effective nutritional interventions.Objective This study aimed to investigate the alleviating effects and potential mechanisms of probiotic-fermented tamarind pulp (FTP) on loperamide-induced constipation in mice.Methods A constipated mouse model was established and treated with low and high-dose FTP (LD‑FTP and HD‑FTP). Assessments included gastrointestinal transit, histopathology, serum neurotransmitters/inflammatory factors, gut microbiota (16S rRNA amplicon sequencing), functional predictions generated using PICRUSt2, and fecal metabolomics (LC-MS).Results FTP dose-dependently alleviated loperamide‑induced constipation. Compared with the model group, HD‑FTP increased small intestinal transit rate by 57.2% (to 92.95%, p Conclusion FTP effectively alleviated constipation by improving intestinal function, reducing inflammation, and remodeling the gut microbiota-metabolite axis. Mechanistically, fermentation-driven tryptophan catabolism and quercetin biotransformation converge on the AhR-NLRP3 axis. These findings highlight FTP as a superior nutritional strategy over UFTP.