On probiotics and irritable bowel syndrome (IBS)

Granted, I am taking a slight departure from the material typically discussed on this blog by introducing the paper by Yan Zhang and colleagues [1] who reported the findings of a meta-analysis examining "the efficacy of different probiotic types, doses and treatment durations in IBS [irritable bowel syndrome] patients diagnosed by Rome III criteria via a meta-analysis of randomized controlled trials (RCTs)." The results however - "Probiotics are an effective pharmacological therapy in IBS patients" - were important enough for me to think about discussing, particularly in the context that IBS might not be stand-alone condition (see here) and some recent research in progress [2] (see here for my take) that could illustrate some wider relevance.

The Zhang paper is open-access so doesn't need any grand rewriting from me in terms of methods or findings but a few things stick out. First is the fact that quite a few different probiotic preparations have been experimentally examined with IBS in mind. From the 21 studies looked at by Zhang et al, we have some recurring themes including different types of Lactobacillus acidophilus and Lactobacillus rhamnosus for example being included in the preparations. The inclusion of a preparation called VSL#3 also caught me eye in light of some discussions about a potential 'antibiotic brain' recently on this blog (see here) and what might reverse this in mice. Of additional note was the use of an old friend: Saccharomyces boulardii that continues to impress [3].

Second, and related to the first point, are the authors conclusions that: "Single probiotics, a low dose, and a short treatment duration were more effective with respect to overall symptom response and QoL [quality of life]." The authors provide some rather interesting forest plots illustrating how the analysed data helped them reach this conclusion; albeit bearing in mind that "the effects of individual probiotic species" were not analysed in the current meta-analysis. In other words, some preparations seem to work pretty well but we don't know enough about which ones used under which circumstances.

Finally, I noted that the whilst the use of a placebo was an important eligibility criteria for inclusion in their meta-analysis - "the studies were randomized controlled trials (RCTs) that compared probiotics with placebo" - the authors did not shy away from the fact that: "An appreciable placebo effect was detected in some studies, which may have minimized the effects of probiotics." Placebo effects and IBS is something again, that has been discussed before on this blog (see here) bearing in mind I'm not saying that IBS is 'all in the mind' or anything like that.

Set within the context of other recent meta-analyses concluding that: "There were alterations of gut microbiota in IBS patients and it implied that alterations of gut microbiota might be involved in the pathogenesis of IBS" [4] one shouldn't necessarily be surprised that there may have been effects from the use of probiotics in cases of IBS. Assuming that an oral probiotic is able to survive the stomach environment and actually colonise [parts of] the gastrointestinal (GI) tract (if only for a defined amount of time) the cost-effectiveness of this intervention coupled with the low rates of side-effects makes for impressive reading in terms of the treatment of at least some cases of IBS.

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[1] Zhang Y. et al. Effects of probiotic type, dose and treatment duration on irritable bowel syndrome diagnosed by Rome III criteria: a meta-analysis. BMC Gastroenterology. 2016; 16: 62.

[2] Santocchi E. et al. Gut to brain interaction in Autism Spectrum Disorders: a randomized controlled trial on the role of probiotics on clinical, biochemical and neurophysiological parameters. BMC Psychiatry. 2016 Jun 4;16:183.

[3] Szajewska H. & Kołodziej M. Systematic review with meta-analysis: Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea. Aliment Pharmacol Ther. 2015 Oct;42(7):793-801.

[4] Zhuang X. et al. Alterations of gut microbiota in patients with irritable bowel syndrome: A systematic review and meta-analysis. J Gastroenterol Hepatol. 2016 Jun 14.

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Zhang Y, Li L, Guo C, Mu D, Feng B, Zuo X, & Li Y (2016). Effects of probiotic type, dose and treatment duration on irritable bowel syndrome diagnosed by Rome III criteria: a meta-analysis. BMC gastroenterology, 16 (1) PMID: 27296254