Clinician Article

Efficacy of prebiotics, probiotics, and synbiotics in irritable bowel syndrome and chronic idiopathic constipation: systematic review and meta-analysis.

  • Ford AC
  • Quigley EM
  • Lacy BE
  • Lembo AJ
  • Saito YA
  • Schiller LR, et al.
Am J Gastroenterol. 2014 Oct;109(10):1547-61; quiz 1546, 1562. doi: 10.1038/ajg.2014.202. Epub 2014 Jul 29. (Review)
PMID: 25070051
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  • Family Medicine (FM)/General Practice (GP)
    Relevance - 6/7
    Newsworthiness - 5/7
  • General Internal Medicine-Primary Care(US)
    Relevance - 6/7
    Newsworthiness - 5/7
  • Pediatrics (General)
    Relevance - 6/7
    Newsworthiness - 5/7
  • Gastroenterology
    Relevance - 6/7
    Newsworthiness - 4/7
  • Internal Medicine
    Relevance - 5/7
    Newsworthiness - 5/7


OBJECTIVES: Irritable bowel syndrome (IBS) and chronic idiopathic constipation (CIC) are functional bowel disorders. Evidence suggests that disturbance in the gastrointestinal microbiota may be implicated in both conditions. We performed a systematic review and meta-analysis to examine the efficacy of prebiotics, probiotics, and synbiotics in IBS and CIC.

METHODS: MEDLINE, EMBASE, and the Cochrane Controlled Trials Register were searched (up to December 2013). Randomized controlled trials (RCTs) recruiting adults with IBS or CIC, which compared prebiotics, probiotics, or synbiotics with placebo or no therapy, were eligible. Dichotomous symptom data were pooled to obtain a relative risk (RR) of remaining symptomatic after therapy, with a 95% confidence interval (CI). Continuous data were pooled using a standardized or weighted mean difference with a 95% CI.

RESULTS: The search strategy identified 3,216 citations. Forty-three RCTs were eligible for inclusion. The RR of IBS symptoms persisting with probiotics vs. placebo was 0.79 (95% CI 0.70-0.89). Probiotics had beneficial effects on global IBS, abdominal pain, bloating, and flatulence scores. Data for prebiotics and synbiotics in IBS were sparse. Probiotics appeared to have beneficial effects in CIC (mean increase in number of stools per week=1.49; 95% CI=1.02-1.96), but there were only two RCTs. Synbiotics also appeared beneficial (RR of failure to respond to therapy=0.78; 95% CI 0.67-0.92). Again, trials for prebiotics were few in number, and no definite conclusions could be drawn.

CONCLUSIONS: Probiotics are effective treatments for IBS, although which individual species and strains are the most beneficial remains unclear. Further evidence is required before the role of prebiotics or synbiotics in IBS is known. The efficacy of all three therapies in CIC is also uncertain.

Clinical Comments

Family Medicine (FM)/General Practice (GP)

This is a common condition that is hard to treat. This meta-analysis suggests only a very modest improvement with probiotics, but this may help some patients.


Obviously, well done systematic reviews are always welcome but some only give us repetitive information. Of course, the quality of the review is critically dependent on the quality of individual reports: probiotics world is urgently needing some type of standardization if some clinical really relevant consequence is to be expected.

Internal Medicine

More than half of the articles had uncertain risk of bias. The heterogeneity of the result were superior of 60% (most of the time); the time to follow up was long (2 weeks to 6 months); the type of dose used was too high. It would have been nice to have had a summary of findings table using the GRADE approach and putting a figure of the funnel plot in the original paper. It looks like the treatments had some favorable results in a short period of time, but in a long run its unknown. The quality of the evidence is uncertain.

Internal Medicine

As an internist, I believe this is a step forward in treating a difficult disease. Are these benefits for all probiotics, for all symptoms of IBS and chronic constipation? No. So how do you prescribe? Do we look at the subgroups of this review and take an individual call for each symptom and probiotic? These are things to ponder.

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