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Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It?
J Neurogastroenterol Motil 2015; 21(4):471-85JN

Abstract

BACKGROUND/AIMS

Despite numerous randomized clinical trials and meta-analyses, there is no increased evidence for the efficacy of probiotics in the treatment of irritable bowel syndrome (IBS). We review this evidence, identify and analyse the reasons for this lack of evidence and propose methodological improvements for future studies.

METHODS

Based on a literature search, we identified 56 papers that matched the purpose of our analyses. Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics. They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures.

RESULTS

Trials in both groups suffered from heterogeneity with respect to probiotic concentration, duration of treatment, and other methodological issues (crossover design and underpowered studies). This heterogeneity did not allow the application of a meta-analytic approach and a systematic review was therefore performed instead. Multi-strain preparations combined 2 to 8 different bacterial subspecies, mostly lactobacilli or bifidobacteria, and used variable lengths of treatments. Overall, more than 50% of trials presented negative outcomes. The majority of the single-strain probiotic trials employing lactobacilli or Saccharomyces were negative, whereas trials employing bifidobacteria showed positive results.

CONCLUSIONS

The heterogeneity of the studies of probiotics in IBS questions the value of meta-analyses. The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity. Current data provides limited evidence for the efficacy of a small number of single-strain probiotics in IBS (mostly bifidobacteria) and sound studies following strict trial guidelines (Food and Drug Administration and European Medicines Agency guidelines for clinical trials) are needed. We summarised and proposed some methodological issues for future studies in the field.

Authors+Show Affiliations

SymbioGruppe GmbH, Herborn, Germany. Department of Psychosomatic Medicine, University Hospital Tübingen, Germany.Department of Psychosomatic Medicine, University Hospital Tübingen, Germany.Center for Endoscopy, Starnberg, Germany.Department of Psychosomatic Medicine, University Hospital Tübingen, Germany.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

26351253

Citation

Mazurak, Nazar, et al. "Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and what Can Be Done About It?" Journal of Neurogastroenterology and Motility, vol. 21, no. 4, 2015, pp. 471-85.
Mazurak N, Broelz E, Storr M, et al. Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It? J Neurogastroenterol Motil. 2015;21(4):471-85.
Mazurak, N., Broelz, E., Storr, M., & Enck, P. (2015). Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It? Journal of Neurogastroenterology and Motility, 21(4), pp. 471-85. doi:10.5056/jnm15071.
Mazurak N, et al. Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and what Can Be Done About It. J Neurogastroenterol Motil. 2015 Oct 1;21(4):471-85. PubMed PMID: 26351253.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It? AU - Mazurak,Nazar, AU - Broelz,Ellen, AU - Storr,Martin, AU - Enck,Paul, PY - 2015/04/29/received PY - 2015/07/22/revised PY - 2015/08/04/accepted PY - 2015/9/10/entrez PY - 2015/9/10/pubmed PY - 2015/9/10/medline KW - Irritable bowel syndrome KW - Probiotics KW - Review SP - 471 EP - 85 JF - Journal of neurogastroenterology and motility JO - J Neurogastroenterol Motil VL - 21 IS - 4 N2 - BACKGROUND/AIMS: Despite numerous randomized clinical trials and meta-analyses, there is no increased evidence for the efficacy of probiotics in the treatment of irritable bowel syndrome (IBS). We review this evidence, identify and analyse the reasons for this lack of evidence and propose methodological improvements for future studies. METHODS: Based on a literature search, we identified 56 papers that matched the purpose of our analyses. Twenty-seven studies used multi-species bacterial preparations and 29 used single-strain probiotics. They were analysed regarding patients included, treatment duration, probiotic dosage, and outcome measures. RESULTS: Trials in both groups suffered from heterogeneity with respect to probiotic concentration, duration of treatment, and other methodological issues (crossover design and underpowered studies). This heterogeneity did not allow the application of a meta-analytic approach and a systematic review was therefore performed instead. Multi-strain preparations combined 2 to 8 different bacterial subspecies, mostly lactobacilli or bifidobacteria, and used variable lengths of treatments. Overall, more than 50% of trials presented negative outcomes. The majority of the single-strain probiotic trials employing lactobacilli or Saccharomyces were negative, whereas trials employing bifidobacteria showed positive results. CONCLUSIONS: The heterogeneity of the studies of probiotics in IBS questions the value of meta-analyses. The use of different bacterial strains and different mixtures of these strains, as well as different dosages, are the main contributors to this heterogeneity. Current data provides limited evidence for the efficacy of a small number of single-strain probiotics in IBS (mostly bifidobacteria) and sound studies following strict trial guidelines (Food and Drug Administration and European Medicines Agency guidelines for clinical trials) are needed. We summarised and proposed some methodological issues for future studies in the field. SN - 2093-0879 UR - https://www.unboundmedicine.com/medline/citation/26351253/full_citation L2 - http://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm15071 DB - PRIME DP - Unbound Medicine ER -