SMALL INTESTINE: Edited by Fergus ShanahanLeaky gut – concept or clinical entity?Quigley, Eamonn M.M.Author Information Division of Gastroenterology and Hepatology, Lynda K. and David M. Underwood Center for Digestive Disorders, Houston Methodist Hospital, Weill Cornell Medical College Houston, Houston, Texas, USA Correspondence to Eamonn M.M. Quigley, MD, FRCP, FACP, MACG, FRCPI, Division of Gastroenterology and Hepatology, Lynda K. and David M. Underwood Center for Digestive Disorders, Houston Methodist Hospital, Weill Cornell Medical College Houston, 6550 Fannin St, SM1001, Houston, TX 77030, USA. E-mail: firstname.lastname@example.org Current Opinion in Gastroenterology: March 2016 - Volume 32 - Issue 2 - p 74-79 doi: 10.1097/MOG.0000000000000243 Buy Metrics Abstract Purpose of review This article evaluates the current status of the gut barrier in gastrointestinal disorders. Recent findings The gut barrier is a complex, multicomponent, interactive, and bidirectional entity that includes, but is not restricted to the epithelial cell layer. Intestinal permeability, the phenomenon most readily and commonly studied, reflects just one (albeit an important one) function of the barrier that is intimately related to and interacts with luminal contents, including the microbiota. The mucosal immune response also influences barrier integrity; effects of inflammation per se must be accounted for in the interpretation of permeability studies in disease states. Summary Although several aspects of barrier function can be assessed in man, one must be aware of exactly what a given test measures, as well as of its limitations. The temptation to employ results from a test of paracellular flux to imply a role for barrier dysfunction in disorders thought to be based on bacterial or macromolecular translocation must be resisted. Although changes in barrier function have been described in several gastrointestinal disorders, their primacy remains to be defined. At present, few studies support efficacy for an intervention that improves barrier function in altering the natural history of a disease process. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.