Tamarind Fiber ingestion improves constipation symptoms: A randomized, double-blind, placebo-controlled, and parallel-group clinical trial

Water-soluble dietary fibers containing bioactive polysaccharides are increasingly studied as strategies to support gastrointestinal and systemic health. Tamarind fiber (TF) contains xyloglucan with potential mucosal barrier protective properties; however, controlled human evidence remains limited. This randomized, double-blind, placebo-controlled trial assessed TF effects on bowel function, fatigue, and skin condition in healthy adults with constipation tendencies. 178 participants received placebo, low-dose (TF 400 mg/day), or high-dose (TF 800 mg/day) for 4 weeks. Compared with placebo, high-dose TF significantly increased defecation frequency (primary outcome). In addition, high-dose TF significantly improved POMS2 Fatigue-Inertia scores and suppressed skin biological elasticity (R7) decline (secondary outcomes), supported by in vitro intestinal barrier protection. These findings suggest that continuous TF intake of 800 mg/day, a relatively low dose compared to conventional dietary fibers, provides clinically meaningful improvements in bowel function, fatigue, and skin health.