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J Altern Complement Med. 2012 Feb;18(2):112-9. doi: 10.1089/acm.2011.0015.

The shortcomings of clinical trials assessing the efficacy of probiotics in irritable bowel syndrome.

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Pharmaceutical Research Institute at Albany College of Pharmacy and Health Sciences, Rensselaer, NY 42101, USA.



Multiple clinical trials within the past decade have aimed to study the safety and efficacy of various probiotic strains in treating patients with irritable bowel syndrome (IBS). However, there exists much heterogenicity in study design among these trials, namely, in bacterial strain, dose, dosage form, sample size, study duration, and population demographics.


The aim of this study was to identify the shortcomings of clinical trials using probiotic treatments in subjects with IBS, so that researchers may realize where limitations exist, allowing them to curtail these limitations in future trials.


An extensive PubMed search was conducted using the following keywords: probiotics in irritable bowel syndrome, probiotic pharmacokinetics, Lactobacillus, Bifidobacterium, Alosetron, Tegaserod, Alosetron, and Tegaserod safety profile. A total of 62 articles were used in constructing this review, with 20 original articles.


Stark differences in study design existed among the 20 original articles analyzed, as well as an outstandingly high "placebo effect," making the ability to compare these articles as a means for evidence-based treatment therapy in IBS very difficult.


Future large, randomized, double-blind, placebo-controlled clinical trials must be conducted, embodying minimal variability in study designs, to appropriately assess the efficacy of specific probiotic strains over placebo.

[Indexed for MEDLINE]

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