Vitamin D and skin diseases: A review

Vitamin D, which was formerly linked to rickets and osteomalacia, has lately been linked to a variety of medical and dermatological conditions. Most cells in the body, including the skin, have vitamin D receptors and enzymatic machinery capable of converting circulating 25-hydroxyvitamin D [25(OH)D] to the active 1,25-hydroxyvitamin D. Vitamin D analogs are well recognized for their anti-proliferative and pro-differentiating actions on keratinocytes, making them helpful in the treatment of psoriasis vulgaris. However, additional functions for vitamin D in skin have been discovered, including immunomodulatory and anti-apoptotic actions, suggesting that it may be used to treat atopic dermatitis and infections. Increasing data suggests that cutaneous vitamin D production may aid in the prevention of skin cancers, as well as that oral vitamin D supplementation may decrease cancer mortality. Low levels of vitamin D have been related to autoimmune disorders like vitiligo in several epidemiological studies, and topical vitamin D has been used to treat vitiligo. This study examines vitamin D's involvement in a variety of skin diseases, with a focus on both its well-known role in psoriasis and its less well-known role in conditions including ichthyosis, TB, and acne.