TOPLINE

A meta-analysis of 13 randomized controlled trials did not find conclusive evidence that fecal microbiota transplantation (FMT) alleviated symptoms of irritable bowel syndrome (IBS).

METHODOLOGY

• Prior small randomized controlled trials suggested that FMT might alleviate symptoms of IBS, but these trials yielded inconsistent results. Researchers conducted an updated systematic review and meta-analysis of randomized controlled trials evaluating the efficacy and safety of FMT in patients with IBS.
• The researchers searched four major databases and reference lists through February 2026 to identify trials involving adults with IBS that compared FMT with placebo or autologous stool.
• The primary outcome was no significant improvement in IBS symptoms between 4 and 24 weeks after FMT.
• Researchers reported the real-world effect of FMT using an intention-to-treat analysis involving all patients randomly assigned to receive treatment and the treatment effect using a per-protocol analysis among those who completed the protocol.
• The risk for bias and certainty of evidence were assessed using relevant tools.

TAKEAWAY

• The analysis included 13 randomized controlled trials involving 693 adults with IBS (25.9%-81.1% women). Most trials had some risk for bias (three had a low risk for bias, whereas 10 had some concerns), and the overall certainty of evidence for symptom outcomes was rated as very low.
• In the intention-to-treat analysis (13 trials), FMT did not significantly reduce IBS symptoms at 12 weeks compared with placebo (heterogeneity [I²] = 80%; P for heterogeneity < .00001).
• In the per-protocol analysis (13 trials), FMT was associated with a reduction in IBS symptoms at 12 weeks (risk ratio, 0.67; 95% CI, 0.46-0.97; I² = 76%; P for heterogeneity < .00001).
• IBS symptom severity scores showed a small improvement with FMT, but the evidence was very uncertain (12 trials). Rates of adverse events, including serious adverse events, did not differ between the groups (11 trials).

IN PRACTICE

“This systematic review and meta-analysis demonstrated that there was no significant difference between FMT and placebo for improvement of IBS symptoms. Subgroups single-dose FMT and IBS diagnosed by Rome IV criteria might have improved clinical outcome; however, future trials are required,” the authors of the study concluded.

SOURCE

The study was led by Natsuda Aumpan and Jun Watanabe, McMaster University, Hamilton, Ontario, Canada. It was published online in Gastroenterology.

LIMITATIONS

The trials differed widely in design, FMT methods, donors, and IBS definitions, resulting in high heterogeneity. Some findings changed when single trials were removed. Overall, the evidence certainty was very low.

DISCLOSURES

The study received funding from the Canadian Institutes of Health Research and the Inflammation, Microbiome, and Alimentation: Gastro-Intestinal and Neuropsychiatric Effects network. One author reported receiving research support from public and academic sources in Thailand.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.