Abstract
Ever since the discovery of the fat-soluble secosteroid vitamin D, an abundance of research has been conducted on the molecular mechanisms for the multiple health benefits of this nutrient. Studies aimed at the beneficial effects of vitamin D supplementation have found appreciable evidence suggesting that it may play a more prime role than initially presumed. Though it has largely been implicated in bone pathophysiology, novel research on vitamin D indicates its fundamental involvement in a wide range of disease processes through its multiple systemic effects including but not limited to metabolic, cardiovascular, anti-inflammatory, antineoplastic, antioxidant, neuroprotective and immune actions. Recent work has yielded important mechanistic insights into the functions of vitamin D in mediating immunity. The present work sheds light on the metabolism and immune response mechanisms of vitamin D. The review is based on a thorough search of the available relevant research findings about the metabolic transformations of vitamin D and the molecular basis of its role in immunity. Apart from its classical mechanistic control of mineral homeostasis, vitamin D has immunomodulatory effects through a variety of mechanisms at both systemic and cellular levels. Disruption of vitamin D reliant molecular pathways in the regulation of immune response can potentially result in development and/or progression of autoimmune and infective processes.