The intestine constitutes the largest interface between a person and his or her environment, and an intact intestinal barrier is thus essential in maintaining health and preventing tissue injury and several diseases. The intestinal barrier has various immunological and non‐immunological components. The epithelial barrier is one of the most important non‐immunological components. Hyperpermeability of this barrier is believed to contribute to the pathogenesis of several gastrointestinal disorders including inflammatory bowel disease, celiac disease and food allergy. Hence, assessing barrier integrity is of the utmost importance. One of the more quantitative gauges for this assessment is transepithelial permeability of various molecular probes, among which sugars are commonly used. Measures of intestinal permeability might also be useful as markers for assessment of prognosis and follow up in various gastrointestinal disorders. The present article is a review of the normal and abnormal functioning of the intestinal barrier, the diseases that can result from loss of barrier integrity, and some promising agents and strategies for restoring barrier normality and integrity.

© 2003 Blackwell Publishing Asia Pty Ltd