Intestinal Permeability: The Basics

Twenty years ago it became possible, with the introduction of nonmetabolized sugars as test substances, to assess intestinal permeability reliably and noninvasively in humans1. Acceptance of the technique was initially slow, mainly because of the confusion that the use of polyethylene glycol (PEG 400) brought with it2,3, but in the past few years there has been a proliferation of published studies, from a wide range of research workers, using these tests to assess various aspects of gastrointestinal diseases. Tests of intestinal permeability may relate to at least five purposes; these are: 1. Diagnostic screening for intestinal disease. 2. Confirming diagnosis; indication of therapeutic response and prognosis. 3. Evaluation of drug-related, dietary and environmental factors upon the intestine. 4. The effect of various physiological factors on intestinal barrier function; for instance, related to diet (e.g. level of food intake and osmolar content), level of nutrition and state of blood flow. 5. To assess the importance of the intestinal barrier function in the etiology, pathophysiology and pathogenesis of intestinal and systemic disease.