Irritable Bowel Syndrome

Irritable Bowel Syndrome (IBS) is one of the most prevalent digestive conditions, causing symptoms like bloating, stomach cramps, diarrhoea and constipation. Although the aetiology and pathophysiology of IBS is known to be multifactorial, there is a growing body of evidence to support the role of the gut microbiota.1-3


Numerous studies have reported differences in the faecal microbiota of patents with IBS compared with healthy controls4-6, with the composition varying depending on the predominant form of IBS7. For example, diarrhoea-predominant IBS was significantly associated with significantly higher levels of Enterobacteriaceae and significantly lower levels of Faecalibacterium prausnitzii compared with healthy controls.8 In general, data suggest that in patients with IBS there is a relative abundance of pro-inflammatory bacteria species such as Enterobacteriaceae, and a corresponding reduction in Lactobacillus and Bifidobacterium.9


One of the strongest arguments supporting the involvement of the gut microbiota in the pathophysiology of IBS is that for some patients, the onset of IBS is preceded by an acute episode of gastroenteritis. In 2006, a meta-analysis reported an odds ratio of 7.3 [95% confidence interval: 4.7–11.1] for developing IBS after a gastrointestinal infection, supporting a link between the two.10  



1. Dupont (2014) Alimentary Pharmacology & Therapeutics 39:1033–42. 

2. Distrutti et al. (2016) World Journal of Gastroenterology 22:2219–41.

3. Rodino-Janeiro et al. (2018) Advanced Therapeutics 35(3):289-310.

4. Durban et al. (2012) Environmental Microbiology Reports 4:242–7.

5. Codling et al. (2010) Digestive Diseases and Sciences 55:392–7.

6. Parkes et al. (2012) Neurogastroenterology and Motility 24:31–9.

7. Kassinen et al. (2007) Gastroenterology 133:24–33.

8. Carroll et al. (2012) Neurogastroenterology and Motility 24:e248.

9. Zhuang et al. (2017) Journal Gastroenterology and Hepatology 32:28–38.

10. Halvorson et al. (2006) America Journal of Gastroenterology 101:1894–9.