Spore-forming Bacillus coagulans SNZ 1969 improved intestinal motility and constipation perception mediated by microbial alterations in healthy adults with mild intermittent constipation: A randomized controlled trial

The spore-forming Bacillus coagulans has attracted attention for their therapeutic action in the colon. However, the mechanism of this action remains unclear. In this study, healthy subjects with mild intermittent constipation were supplemented with B. coagulans SNZ 1969 (BC) or the placebo for 8 weeks (n = 80). Then, we assessed colonic transit time (CTT), weekly complete spontaneous bowel movement (CSBM) scores, bowel discomfort symptom (BDS) scores, and 16S rRNA fecal microbiome profiles. The association between the critically altered gut microbiome and clinical outcomes was analyzed using redundancy analysis (RDA) and validated by receiver operating characteristic (ROC) curves. BC supplementation significantly improved CTT (p = 0.031), CSBM at weeks 2 (p = 0.045) and 9 (p = 0.038), and BDS at weeks 3 (p = 0.019) and 6 (p = 0.029) compared with the placebo, while altering the community composition of the gut microbiota. We also confirmed that BC was effectively delivered to the gut. Finally, the multivariate redundancy analysis concluded that BC-induced enrichment of Lactobacillales and diminishment of Synergistales were related to CTT improvements. This study provides important new data on how spore-forming B. coagulans SNZ 1969 contributes to improving gut motility and presents evidence supporting the use of B. coagulans SNZ 1969 in adults with mild intermittent constipation and habitual low intake of fruit and vegetables.