Vitamin D can be synthesized in the skin when it is exposed to sunlight and is then metabolized in the liver and kidney to the metabolically active form called 1α,25-dihydroxyvitamin D. Through binding to the vitamin D receptor (VDR), 1α,25-dihydroxyvitamin D can regulate the expression of hundreds of genes involved in skeletal and other biological functions (1). Vitamin D exhibits many non-skeletal effects, particularly on the immune system. Acting through the