Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, affecting more than 10% of the population, with the highest impact in women. Although its origin is still unknown, reduced gut microbial diversity could be involved in its development.
Clinically, IBS can only be identified by the symptoms: usually a combination of symptoms including abdominal pain or discomfort, abnormal bloating, and changes in stool frequency and consistency. Psychological factors, stress levels, lifestyle and diet reportedly affect IBS symptoms.
New therapeutic approaches with the potential to alter gut microbiota have recently been identified, and include the low fermentable, oligo-, di-, monosaccharides, and polyols (FODMAP) diet, antibiotics, and probiotics.
A recent meta-analysis of twenty-one randomized controlled trials has assessed the efficacy of different types of probiotics, doses and treatment durations in IBS patients with the Rome III criteria serving as the diagnostic criteria. It concluded that probiotic use could significantly improve overall symptoms and quality of life in IBS patients compared with placebo. No significant differences were found in the relief of individual IBS symptoms, including abdominal pain and bloating, between probiotics and placebo; this may be explained by both the ineffectiveness of administering the individual probiotics Lactobacillus and Bifidobacteria and by the different diagnostic criteria and different methods of quantifying individual IBS symptoms. Besides this, it is still unclear whether multi-species probiotics are more effective than mono-species probiotics for IBS symptoms. Regarding probiotic doses, the effect of a probiotic on the overall symptom response and quality of life seems not to be dose dependent. On the other hand, short treatment duration (less than 8 weeks) may be more effective than a long duration (8 weeks or more) for improving overall symptom response and quality of life. On the whole, the authors conclude that probiotics at a low dose and with a short treatment duration appear to be most effective in improving overall symptom response and quality of life. The advantages of using either multi- or mono-species probiotics are still not clear.
Regarding paediatric populations, a recent multicentre, randomized, double-blind, placebo-controlled, crossover trial found that in children 8-18 years with IBS a daily mixture of a sachet consisting of 3 billion Bifidobacterium longum BB536, 1 billion B. infantis M-63, and 1 billion B. breve M-16V ingested for 6 weeks was associated with improvement in abdominal pain and quality of life.
In conclusion, these results demonstrate that probiotic supplementation is an effective therapy for those with IBS. Future studies of the effects of probiotics in IBS should focus on probiotic type (multi- or mono-species probiotics), strain, dose, and treatment duration for larger populations to confirm and extend these findings.
Giannetti E, Maglione M, Alessandrella A, et al. A mixture of 3 bifidobacteria decreases abdominal pain and improves the quality of life in children with irritable bowel syndrome: a multicenter, randomized, double-blind, placebo-controlled, crossover trial. J Clin Gastroenterol. 2016. doi:10.1097/MCG.0000000000000528.
Zhang Y, Li L, Guo C, et al. Effects of probiotic type, dose and treatment duration on irritable bowel syndrome diagnosed by Rome III criteria: a meta-analysis. BMC Gastroenterol. 2016; 16(1):62. doi:10.1186/s12876-016-0470-z.