Explain Viscosity of Gastrointestinal Contents Delay Absorption?

1. Inadequate mixing of luminal contents due to increased viscosity may slow the movement of digestive enzymes to their substrate thus delaying digestion; and

2. Viscous properties inhibit the access of nutrients to the epithelium. Nutrients have to diffuse across the thin, relatively unstirred layer of fluid lying adjacent to epithelium. This is achieved by intestinal contractions, which create convection currents, thus bringing the material from the centre of the lumen close to the epithelium. Increasing the viscosity of the luminal content impairs convective effects and thus delays absorption.