The prevalence of vitamin D deficiency/insufficiency is estimated in over a billion people world-wide . Vitamin D has potential mechanisms not only in the balance of calcium and bone homeostasis, but also a key modulator of the immune system. Vitamin D receptors (VDRs) are located on all nucleated cells including the GI tract. Thus far, there is already accumulating evidence for a role for vitamin D supplementation in inflammatory bowel disease (IBD). A recent systematic review suggested there may be benefits of vitamin D supplementation in IBD.