Studies suggest that Vitamin D may be very important for maintaining proper barrier integrity:

• Novel role of the vitamin D receptor in maintaining the integrity of the intestinal mucosal barrier.

• Effects of the cathelicidin LL-37 on intestinal epithelial barrier integrity.

• Vitamin D Receptor and Coactivators SRC2 and 3 Regulate Epidermis-Specific Sphingolipid Production and Permeability Barrier Formation.