Vitamin D and intestinal homeostasis: Barrier, microbiota, and immune modulation.

•Vitamin D plays a pivotal role in maintaining intestinal homeostasis.•Vitamin D limits microbiota entrance into the interstitium.•Should bacteria invade the lamina propria, immune cells clear the affected site.•Vitamin D subdues the immune response, thereby restoring homeostasis.•Significant limitations preclude universal acceptance of vitamin D for IBD therapy.