Antibiotic-like actions of vitamin D.

Vitamin D is a secosteroid hormone that has expanding importance for a healthy lifestyle and disease prevention. A multitude of studies have highlighted that vitamin D acts not only in bone and calcium homeostasis but is critically important for human immunity. The discovery that the storage form of vitamin D (25-hydroxyvitamin D3) can be locally converted to the active form (1,25-hydroxyvitamin D3) in immune cells, epithelial cells and numerous other non-renal tissues highlights the importance of maintaining sufficient stores. When responding to a specific external stimulus, like bacterial invasion, intracrine synthesis of active vitamin D has the ability to regulate gene expression providing a specific response and directing cellular actions. These responses include the generation of antimicrobial peptides with production of these peptides dependent on vitamin D status. Vitamin D deficiency is associated with an increased rate of infection. This paper highlights the antibiotic like actions of vitamin D and importance of vitamin D sufficiency.