A review of the role of the gut microflora in irritable bowel syndrome and the effects of probiotics

Abstract

Irritable bowel syndrome (IBS) is a multi-factorial gastrointestinal condition affecting 8 -22 % of the population with a higher prevalence in women and accounting for 20 -50 % of referrals to gastroenterology clinics. It is characterised by abdominal pain, excessive flatus, variable bowel habit and abdominal bloating for which there is no evidence of detectable organic disease. Suggested aetiologies include gut motility and psychological disorders, psychophysiological phenomena and colonic malfermentation. The faecal microflora in IBS has been shown to be abnormal with higher numbers of facultative organisms and low numbers of lactobacilli and bifidobacteria. Although there is no evidence of food allergy in IBS, food intolerance has been identified and exclusion diets are beneficial to many IBS patients. Food intolerance may be due to abnormal fermentation of food residues in the colon, as a result of disruption of the normal flora. The role of probiotics in IBS has not been clearly defined. Some studies have shown improvements in pain and flatulence in response to probiotic administration, whilst others have shown no symptomatic improvement. It is possible that the future role of probiotics in IBS will lie in prevention, rather than cure.

Prevalence and temporal stability of selected clostridial groups in irritable bowel syndrome in relation to predominant faecal bacteria

“…The differences in faecal bacterial population between IBS and control subjects have been reported in several studies (Balsari et al, 1982;Bradley et al, 1987;Madden & Hunter, 2002;Mättö et al, 2005). We found a marked difference in the proportions of the C. coccoides-E. rectale group of clostridia between constipation-type IBS subjects and control subjects.…”

“…The existence of abnormal colonic fermentation in IBS (King et al, 1998) and alleviation of IBS symptoms by eradication of small intestinal bacterial overgrowth by antibiotic therapy (Pimentel et al, 2000), suggest that the intestinal microbiota has a role in IBS. Some studies have reported differences in the faecal bacterial population between IBS and control subjects (Balsari et al, 1982;Bradley et al, 1987;Madden & Hunter, 2002;Mättö et al, 2005;Malinen et al, 2005). However, the results obtained in earlier studies are partly contradictory, and with the exception of those of Mättö et al (2005) and Malinen et al (2005), are based on the culture-based analysis of the microbiota.…”

“…Transient disturbance of the intestinal microbiota during antibiotic therapy has been shown in several studies (Edlund & Nord, 2000; Donskey et al, 2003). Changes in the intestinal microbiota have also been suggested to occur in certain intestinal diseases and disorders, such as inflammatory bowel disease (IBD) (Seksik et al, 2003) and irritable bowel syndrome (IBS) (Madden & Hunter, 2002). IBS is an intestinal disorder that involves continuous or recurrent intestinal pain or discomfort that is relieved during defecation.…”

Probiotics - What They Are, Their Benefits and Challenges

“…IBD is a collection of disorders including ulcerative colitis, Crohn's disease and pouchitis, characterized by chronic or recurrent inflammation, ulceration and abnormal narrowing of the GIT resulting in abdominal pain, diarrhoea and gastrointestinal bleeding (Hanauer, 2006;Marteau et al, 2001). IBS is typically characterized by abdominal pain, excessive flatus, variable bowel habit and bloating (Madden & Hunter, 2002). Several studies have been conducted to investigate the efficacy of probiotics in treatment of IBD (Guandalini, 2002;Ma et al, 2004;Zhang et al, 2005).…”

Bloating and functional gastro-intestinal disorders: Where are we and where are we going?

“…However, the relevance of these data has been questioned for both the low reliability of the test, the weak clinical response to antibiotic therapy and the low placebo effect compared to other IBS studies [41] . However, there is general agreement that at least in a proportion of patients with IBS and bloating [42][43][44] an increased bacterial fermentation can contribute to the symptoms [45] . The net effect of colonic microflora on gas metabolism depends on the balance between gas-producing and gas-consuming microorganisms, which varies considerably among individuals [46] .…”