As growing evidence indicates that constipation is closely linked to gut dysbiosis, probiotics have gained increasing attention from researchers in the treatment of the condition.
Studies have found a trend toward reduced abundance of traditional probiotics such as Bifidobacterium and Lactobacillus in the intestines of people with functional constipation.
Among the species of Bacillus genus, Weizmannia coagulans (W. coagulans)—including W. coagulans BC99—has also demonstrated a positive effect on constipation.
However, the underlying mechanisms of action of W. coagulans BC99 against constipation, from the perspective of gut microbiota, remain unclear.
To evaluate these effects, a randomized, double-blind, placebo-controlled trial was conducted from July to October 2024 at the College of Food and Bioengineering, Henan University of Science and Technology.
A total of 100 adults with constipation were recruited and divided into two groups, with 88 of them completing the study.
Participants in the intervention group consumed W. coagulans BC99 probiotic powder (10 billion CFU per day) provided by Wecare Probiotics Co Ltd, while those in the placebo group ingested maltodextrin (1g per packet). These were taken twice daily for eight weeks.
Overall, the findings showed that BC99 significantly improved bowel movement frequency, stool characteristics, and psychological well-being through multi-faceted mechanisms.
Improved intestinal motility, well-being
Compared with the placebo group, Completely Spontaneous Bowel Movements (CSBM) and Bristol Fecal Characteristics Scale (BSFS) scores of the BC99 group at eighth week significantly increased, indicating that the intervention improved constipation symptoms and increased the frequency of spontaneous bowel movements in patients.
Furthermore, the Depression Anxiety Stress Scale-21 (DASS-21) score of the BC99 group at the end of the study was significantly lower than that of the placebo group, suggesting that BC99 intake was able to relieve anxiety and depression in the participants.
This also means that BC99 not only enhances bowel function, but also ameliorates the psychological distress often associated with chronic constipation, thereby improving overall quality of life.
The barium transit time in the BC99 group was significantly shorter than in the placebo group across the colon. Notably, the most pronounced effect was observed in the ascending colon.
The total intestinal transit time in the BC99 group was also significantly shorter compared to the placebo group, further supporting that BC99 supplementation effectively enhanced gut motility.
Gastrointestinal regulatory peptides are crucial in people with constipation.
After the eight-week intervention, the levels of vasoactive intestinal peptide (VIP - which promotes intestinal motility), gas, and the potent vasodilator calcitonin gene-related peptide (CGRP) in the BC99 group significantly increased, while the levels of endothelin-1 (ET-1, a vasoconstrictor) and somatostatin (SS, a hormone that reduces decreases intestinal motility).
Healthier microbial ecosystem
Analysis of the gut microbiome revealed that BC99 supplementation was associated with increases in the relative abundance of Bacteroidetes and Bacillota, while the abundance of Actinomycetota, Pseudomonadota and Verrucomicrobiota decreased.
Importantly, the researchers observed an increased relative abundance of beneficial genera such as Lactobacillus, Bifidobacterium, Phascolarctobacterium, and Prevotella_9, alongside a decrease in potentially harmful genera like Escherichia-Shigella, Dialister, and Collinsella.
These changes are consistent with a healthier microbial ecosystem, which may elevate intestinal barrier function and reduce inflammation.
Studies have shown that after infection with certain Shigella strains, subjects may experience constipation, which is caused by the invasion of the pathogen on the colon mucosa and the inflammatory response.
Changes in fecal SCFAs levels
After the eight-week intervention, the abundance of the short chain fatty acids (SCFAs) acetic acid and propionic acid was higher in BC99 group than in the placebo group.
Compared with the control, the concentration of acetic acid, butyric acid, and isovaleric acid in feces for the BC99 group significantly increased, while no significant changes were observed in levels of propionic acid, isobutyric acid, and valeric acid.
According to previous studies, SCFAs play important roles in maintaining intestine health, and the concentration of SCFAs increases with the improvement of constipation symptoms.
Therefore, findings from the present study posit that the mitigative effect of BC99 supplementation on constipation could be partially due to an increment in SCFAs levels.
Moreover, the positive correlation between SCFA levels and Lachnoclostridium suggests that BC99 may alleviate constipation partly through enriching SCFA-producing taxa and augmenting microbial metabolite production.
“Collectively, our findings support the potential of BC99 as a safe and effective probiotic intervention for constipation management through integrated mechanisms involving enhanced intestinal motility, regulation of neuroendocrine factors, restoration of gut microbial balance, and increased production of beneficial microbial metabolites,” the authors concluded.
“Future studies with larger cohorts and longer follow-up periods are warranted to explore long-term outcomes and personalized probiotic strategies.”
Source: European Journal of Nutrition. doi: 10.1007/s00394-026-03953-5. “Weizmannia coagulans BC99 improved intestinal motility and chronic constipation through regulating gut microbiota: a randomized, double-blind, placebo-controlled trial”. Authors: Ying Wu, et al.
