The intestinal microbiota and probiotics in irritable bowel syndrome

Abstract

Irritable bowel syndrome (IBS) is a poorly understood gastrointestinal condition affecting approximately onefifth of the UK population, with a higher prevalence in women and accounting for up to half of referrals to gastroenterology clinics in the UK. It is characterized by abdominal pain, excessive flatus, variable bowel habit and abdominal bloating with no evidence of organic disease. IBS commonly occurs after gastroenteritis or following a course of antibiotics. Suggested aetiologies include motility and psychological disorders and psychophysiological phenomena, although there is also evidence that disruption to the intestinal microbiota can play a role in IBS. Episodes such as hysterectomy, first incidence of bacterial gastroenteritis or a course of antibiotics have been shown to contribute to symptoms compatible with those of IBS. The intestinal microflora in IBS has been shown to differ from that of healthy individuals. Faecal microfloras of IBS patients harbour higher numbers of facultative organisms, such as Klebsiella spp. and enterococci, and low numbers of lactobacilli and bifidobacteria. The role of probiotics in IBS has not been clearly defined. Some studies have shown improvements in pain and flatulence in response to probiotic supplementation, while others have shown no symptomatic or objective improvements. Administration of probiotics reduced caecal and faecal yeast proliferation in IBS patients treated with antibiotics, suggesting that they prevent the disruption of the intestinal microbiota known to be associated with IBS. It is possible that the role of probiotics in the management of IBS will lie in prevention, rather than cure.

Intestinal microbiota, diet and health

“…IBS can be difficult to diagnose due to the lack of a biological or pathogenic marker (98,99) . Although the pathophysiology of IBS is still not well understood, several factors are thought to play a role.…”

“…Although the pathophysiology of IBS is still not well understood, several factors are thought to play a role. These include malfermentation of food ingredients, altered microbial composition, intestinal motor and sensory dysfunction, immune mechanisms, psychological factors and brain -gut axis dysregulation (99,102,103) . Considerable evidence suggests that factors that disturb the gut microbiota, such as gastroenteritis, may contribute to the development of IBS (104) .…”