Explore the gastrointestinal environment as a critical path to balance and imbalance~wellness and illness. The intestinal environment comprises our primary interface with our external world, being the portal for 30-50 tons of macronutrients and micronutrients during our lifetimes. This lecture will frame disease risk within the context of digestion/absorption, inflammation/infection/intestinal permeability, GI dysbiosis. Review diagnostic and therapeutic approaches to clinically common GI complaints that are based on returning the gastrointestinal tract to homeostasis.