In a meta-analysis of randomized clinical trials (RCTs), researchers sought to assess and rank the effectiveness of various probiotics in the treatment of irritable bowel syndrome (IBS). According to lead author, Tao Zhang, the investigators’ network meta-analysis (NMA) suggested that the probiotic bacillus coagulans was optimal for treating patients with IBS.

In the article, published in Frontiers in Cellular and Infection Microbiology, the investigators proposed that “incorporating bacillus coagulans into a probiotic combination, or genetically engineering it to amplify its biological function may be a future research target to treat IBS patients.”

The NMA included 43 RCTs that assessed the efficacy of various probiotics in patients with IBS. The primary measures were symptom relief rate and scores in global symptoms, abdominal pain, bloating, and straining. Additional analyses were performed to determine if treatment length or dose affected efficacy.

The included articles covered 5,531 patients with IBS. Among the probiotic species assessed, the authors reported that “bacillus coagulans exhibited the highest probability to be the optimal specie in improving IBS symptom relief rate, as well as global symptom, abdominal pain, bloating, and straining scores.”

Authors identified another potentially valuable probiotic, lactiplantibacillus plantarum (L.plantarum), which was the most effective treatment in improving quality of life—however, it had no significant differences vs other species in standardized mean difference estimates. L.plantarum also had the lowest rate of adverse events among the probiotics in the NMA.

Ultimately, the authors advanced that treatment with bacillus coagulans over 8 weeks, regardless of dose, was the most effective probiotic for abdominal pain and straining scores. The investigators noted that there are few direct comparisons between individual current treatments, so this NMA may have value in establishing treatment guidelines for IBS with probiotics.