IntroductionPrinciple of Intestinal PermeabilityAssessment of intestinal permeability is done to assess the overall function of transport through the intestinal epithelial paracellular route.1 Transport of molecules across the intestinal epithelium takes place through two major routes, ie, trans-cellular and paracellular. Transport of solutes across the transcellular route is carrier-mediated and occurs with the help of transporters and channels. Transport of molecules through paracellular route across the intestinal epithelium occurs by the process of diffusion and it is not carrier-mediated. Intact intestinal epithelial barrier is essential for preventing penetration of the intestinal mucosa by the noxious substances. The disruption of this barrier system results in "leaky" intestine leading to increase in intestinal permeability.2 Intestinal permeability is the property of intestinal epithelium by which it allows the molecules to pass through by non-mediated diffusion.3Intestinal pe...