Effects of konjac glucomannan on gastrointestinal symptoms and gut microbiota in athletes with functional constipation: a double-blind randomized controlled trial.

purposeAthletes are at increased risk for functional constipation due to high-intensity training, irregular diets, and disrupted circadian rhythms. Soluble fibers, particularly konjac glucomannan (KGM), have shown potential in alleviating constipation, but clinical evidence, especially in athletes, is limited. This study aimed to assess the effects of an 8-week KGM intervention on gastrointestinal symptoms and gut microbiota in elite male Taekwondo athletes with functional constipation.

methodsIn this double-blind randomized controlled trial, we enrolled male elite Taekwondo athletes diagnosed with functional constipation according to Rome IV criteria. Participants were randomly assigned to receive either KGM supplementation (dietary intervention group, DG) or placebo (control group, CG) for 8 weeks. Primary outcomes included the Patient Assessment of Constipation Symptoms (PAC-SYM), Patient Assessment of Constipation Quality of Life (PAC-QoL), bowel movement frequency (BMF), Bristol Stool Scale, and the Bowel Function Index (BFI). Stool samples were collected for 16S rRNA gene sequencing to evaluate microbial composition and diversity.

resultsCompared to the placebo group, the KGM group exhibited significant improvements in PAC-SYM, PAC-QoL, BMF, and BFI scores (p < 0.05 for all). Microbial analysis revealed a marked increase in α-diversity and elevated relative abundances of Prevotella_9, Phascolarctobacterium, Lactobacillus, Bacteroides, and members of the Prevotellaceae family, alongside reduced levels of Alistipes and Desulfovibrio. Correlation analyses indicated a strong association between microbial shifts and symptom improvement. Functional predictions further suggested differential expression in microbial metabolic pathways, including upregulation of biotin biosynthesis I and nitrate reduction VI (assimilatory), and downregulation of L-methionine biosynthesis III (all p < 0.05).

conclusionsKonjac glucomannan significantly ameliorated gastrointestinal symptoms in elite athletes with functional constipation, potentially via modulation of the gut microbiota.