Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis
Vivek C. Goodoory et al.
BACKGROUND & AIMS: Some probiotics may be beneficial in irritable bowel syndrome (IBS), but differences in species and strains used, as well as endpoints reported, have hampered attempts to make specific recommendations as to which should be preferred. We updated our previous meta-analysis examining this issue. METHODS: MEDLINE, EMBASE, and the Cochrane Controlled Trials Register were searched (up to March 2023). Randomized controlled trials (RCTs) recruiting adults with IBS, comparing probiotics with placebo were eligible. Dichotomous symptom data were pooled to obtain a relative risk of global symptoms, abdominal pain, or abdominal bloating or distension persisting after therapy, with a 95% confidence interval (CI). Continuous data were pooled using a standardized mean difference with a 95% CI. Adverse events data were also pooled. RESULTS: We identified 82 eligible trials, containing 10,332 patients. Only 24 RCTs were at low risk of bias across all domains. For global symptoms, there was moderate certainty in the evidence for a benefit of Escherichia strains, low certainty for Lactobacillus strains and Lactobacillus plantarum 299V, and very low certainty for combination probiotics, LacClean Gold S, Duolac 7s, and Bacillus strains. For abdominal pain, there was low certainty in the evidence for a benefit of Saccharomyces cerevisae I-3856 and Bifidobacterium strains, and very low certainty for combination probiotics, Lactobacillus, Saccharomyces, and Bacillus strains. For abdominal bloating or distension there was very low certainty in the evidence for a benefit of combination probiotics and Bacillus strains. The relative risk of experiencing any adverse event, in 55 trials, including more than 7000 patients, was not signifi- cantly higher with probiotics. CONCLUSIONS: Some combinations of probiotics or strains may be beneficial in IBS. However, certainty in the evidence for efficacy by GRADE criteria was low to very low across almost all of our analyses.
WHAT YOU NEED TO KNOW
BACKGROUND AND CONTEXT
Irritable bowel syndrome is a chronic disorder of gut-brain interaction that impacts greatly on the quality of life of patients. Probiotics may be efficacious for treatment but the evidence is conflicting.
NEW FINDINGS
For global symptoms, there was moderate certainty for benefit of Escherichia strains, low certainty for Lactobacillus strains and Lactobacillus plantarum 299V, and very low certainty for combination probiotics and Bacillus strains. For abdominal pain, there was low certainty for benefit of Saccharomyces cerevisiae I-3856 and Bifidobacterium strains, and very low certainty for combination probiotics, Lactobacillus, Saccharomyces, and Bacillus strains.
LIMITATIONS
Few trials were low risk of bias and there was heterogeneity between studies and evidence of publication bias in some of our analyses.
CLINICAL RESEARCH RELEVANCE
Future randomized controlled trials could focus on some of the species and strains, or combinations thereof, that appear promising from the data reported here but should also report their methodology and data analysis in sufficient detail to remove any concerns about potential within-trial bias.
BASIC RESEARCH RELEVANCE
Future studies could focus on some of the species and strains, or combinations thereof, to establish the mechanism(s) in which they help alleviate symptoms of irritable bowel syndrome.