Update on the role of systemic vitamin D in atopic dermatitis.

Atopic dermatitis (AD) is a common chronic inflammatory type of eczema. The underlying cause of AD has not been established. Several studies have shown initial epidermal barrier dysfunction with subsequent immune activation as the underlying mechanism. Recently, in addition to its classical role in calcium homeostasis, vitamin D has been recognized for its effect on immunomodulation. Animal studies, case reports, and randomized clinical trials have suggested that vitamin D, through various mechanisms, may alleviate the symptoms of AD. The majority of these studies indicate an inverse relationship between the severity of atopic dermatitis and vitamin D levels. Furthermore, studies have shown that, in individuals with AD who are deficient in vitamin D, repletion of vitamin D results in decreased severity of disease. We present a review of the present literature that suggests a potentially significant role for vitamin D in the treatment of AD.