Inflammatory bowel disease and irritable bowel syndrome: similarities and differences

Purpose of review Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are classically viewed as dichotomous conditions. The former is perceived as a typical organic disease, and the latter is regarded as a disorder of gut function driven by mood. Recent research identified some shared contributing factors, which will be discussed here. Recent findings Mounting evidence shows the importance in both IBD and IBS of genetic, microbiological, epithelial, and immunological factors. In some instances, these factors overlap in the two conditions as shown by: involvement of brain-gut axis dysfunction in IBD, implication of TNFSF gene in Crohn's disease and IBS, evidence of abnormal microbiota and its impact on host functions, identification of low-grade inflammation in subsets of IBS patients, and development of IBS symptoms in patients with IBD in remission. Summary IBD and IBS remain separate conditions although there are some overlapping mechanisms. Both research and clinical management would benefit from considering a functional approach for certain manifestations of IBD and accepting an organic view in subsets of IBS patients.