Vitamin D is a fat-soluble steroid hormone that is crucial for human health. Since long the role of epidermal keratinocytes in the UVB-induced photochemical conversion of 7-dehydrocholesterol to vitamin D3 is known, and also for the enzymatically controlled hydroxylation of the photolysis product. This whole process results in the formation of the biologically active final product 1, 25-(OH)2 D3 (Calcitriol). Moreover recently various research articles have shown benefits of calcitriol and various other vitamin D analogues having a therapeutic role in various dermatologic conditions like psoriasis, atopic dermatitis, acne, vitiligo owing to its anti-inflammatory, antiproliferative action. The present review shows a summary of role of vitamin D in dermatologic perspective. KEYWORDS: Vitamin D, calcitriol, anti-inflammatory, anti-proliferative.
INTRODUCTION:Vitamin D is a fat-soluble prohormone and was identified after the discovery of the anti-rachitic effect of cod liver oil somewhere in the early part of the 20 th century. This vitamin which was found in cod liver oil was assigned as "vitamin D" following Vitamin A, B and C. 1 Vitamin D has two major biologically inert precursors, vitamin D3 (Cholecalciferol) and vitamin D2 (Ergocalciferol). 2,3 Out of these precursors, vitamin D3 is formed from 7-dehydrocholesterol present in the skin, which following exposure to solar ultraviolet B (UVB, 290-320 nm), is converted to previtamin D3. Previtamin D3 is immediately converted to vitamin D in a heat dependent process. Moreover excess of UVB rays also transform previtamin D3 into biologically inactive metabolites, tachysterol and lumisterol. On the other hand, the other precursor vitamin D2 is plant derived and its source is through diet. 1 Vitamin D has both endocrine and autocrine functions. The endocrine role of vitamin D is mainly in serum calcium homeostasis.The autocrine effects of vitamin D depend mainly on genetic transcription specific to the various types of cells expressing nuclear vitamin D receptors. These functions lead to inhibition of cell proliferation, promotion of cell differentiation and apoptosis. Thus vitamin D has an important role in modulation of calcium homeostasis, cardiovascular dynamics, musculoskeletal health and genetic expression. 4,5,6 In Dermatology, topical vitamin D and its analogues are being used since time immemorial in various conditions like vitiligo, psoriasis in the form calcitriol, calcipotriol, etc. Recently vitamin D deficiency and its reduced levels in serum has been seen in various skin diseases.