Do probiotics improve symptoms in patients with irritable bowel syndrome?

There is increasing evidence that inflammation or a disturbance of the flora within the gut might contribute to the pathogenesis of irritable bowel syndrome (IBS), at least in a proportion of cases. As a consequence it has been speculated that, as some probiotic bacteria have a range of anti-inflammatory and immunomodulatory properties, the administration of such organisms might prove to be beneficial in this condition. It has to be acknowledged that the quality and design of trials of probiotics in IBS has been somewhat variable but the majority have shown benefit, although some bacteria appear to be more effective than others. More recent studies using Bifidobacterium infantis 35624 and Bifidobacterium lactis DN-173-010 have given particularly encouraging results. Issues for the future include determining which organisms are most effective, defining optimal doses, comparing methods of delivery and assessing the role of mixtures or the addition of prebiotics.