Strain-Specific and Outcome-Specific Efficacy of Probiotics for the Treatment of Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis

Abstract

Background: Consistent guidance for choosing an appropriate probiotic for the treatment of irritable bowel syndrome is lacking. Methods: A literature search of databases (PubMed, Google Scholar and NIH registry of clinical trials) were searched from inception to June 2021. Inclusion criteria: randomized controlled trials enrolling adult or pediatric IBS patients comparing probiotics against controls, >2 RCTs with common IBS outcome measures within each type of probiotic. Five common measures of IBS symptoms (changes in global IBS-SSS scores, frequency of global responders, changes in bloating or abdominal pain scores and frequency of abdominal pain relief) were used. Findings: We screened 521 studies and included 42 randomized controlled trials (45 treatment arms, N=3856). Four probiotics demonstrated significant reduction in abdominal pain relief: B. coagulans MTCC5260 (RR=4.9, 95% C.I. 3.3, 7.3), L. plantarum 299v (RR=4.6, 95% CI 1.9, 11.0), S. boulardii CNCMI-745 (RR=1.5, 95% C.I. 1.1, 2.1) and S. cerevisiae CNCM I-3856 (RR=1.3, 95% C.I. 1.04, 1.6). Mild-moderate adverse events were reported in 51% of the trials, none were more associated with the probiotic compared to controls. Interpretation: Although the analysis of probiotics was limited by the diversity of IBS outcomes used in trials, six single-strain probiotics and three different types of probiotic mixtures showed significant efficacy for at least one IBS outcome measure. It is now possible to identify specific probiotics that are effective for IBS patients. Funding: None to declare. Declaration of Interest: LVM is on the Scientific Advisory Board of Bio-K+ (Bio-K PLUS, Canada) and on the Biocodex Microbiome Board (Biocodex, France) and is a paid lecturer for Bio-K+ and Biocodex. None of the authors own stock or equity in any of these companies. TK and AK declared no conflicts of interest.