Research article

A systematic review and meta-analysis: probiotics in the treatment of irritable bowel syndrome

Nourieh Hoveyda¹ , Carl Heneghan¹ , Kamal R Mahtani¹ , Rafael Perera¹ , Nia Roberts² and Paul Glasziou¹

¹Department of Primary Health Care, Centre for Evidence Based Medicine, University of Oxford, Rosemary Rue Building, Old Road Campus, Headington, Oxford, OX3 7LF, UK

²University of Oxford Health Care Libraries, Old Road Campus Library, Old Road Campus, Oxford, OX3 7LF, UK

author email corresponding author email

BMC Gastroenterology 2009, 9:15doi:10.1186/1471-230X-9-15

Published:	16 February 2009

Abstract

Background

Irritable Bowel Syndrome (IBS) is a common chronic gastrointestinal disorder and the evidence for efficacy of most drug therapies in the treatment of IBS is weak. A popular alternative is probiotics, which have been used in several conditions. including IBS. Probiotics are live microbial food supplements.

The aim of this systematic review and meta-analysis of randomized trials study was to evaluate the efficacy of probiotics in alleviating symptoms in patients with irritable bowel syndrome. We searched Ovid versions of MEDLINE (1950–2007), EMBASE (1980–2007), CINAHL (1982–2007), AMED (1985–2007), the Cochrane library and hand searched retrieved papers.

Results

We identified 14 randomized placebo controlled trials. Combined data suggested a modest improvement in overall symptoms after several weeks of treatment: for dichotomous data from seven trials the overall Odds Ratio (OR) was 1.6 (95% CI, 1.2 to 2.2); for continuous data from six trials the standardised mean difference (SMD) was 0.23 (95% CI, 0.07 to 0.38).

For individual symptoms the results differed between the pooled dichotomous and pooled continuous data. Trials varied in relation to the length of treatment (4–26 weeks), dose, organisms and strengths of probiotics used.

Conclusion

Probiotics may have a role in alleviating some of the symptoms of IBS, a condition for which currently evidence of efficacy of drug therapies is weak. However, as IBS is a condition that is chronic and usually intermittent longer term trials are recommended. Such research should focus on the type, optimal dose of probiotics and the subgroups of patients who are likely to benefit the most.