Vitamin D for infections

Purpose of review Current data clearly support an interaction of vitamin D with cells of the immune system apart from its regulatory role in calcium homeostasis. The discovery that immune cells express the vitamin D receptor and are capable of metabolizing circulating 25-hydroxyvitamin D into its active form, 1,25-dihydroxyvitamin D, has revolutionized the field and suggested a regulatory role on both the innate and adaptive immune systems. Recent findings Of particular interest with respect to infectious diseases, 1,25-dihydroxyvitamin D has been shown to trigger the production of antimicrobial peptides with a direct pathogen-killing capacity. Interestingly, pathogen-derived components influence the key players in the vitamin D metabolizing pathway, further supporting such an interaction. Summary Here, we review the potential mechanisms of vitamin D in promoting the innate immune response against infectious agents and discuss the possible implications for such a response in the prevention of or the intervention in various infectious diseases.