The Clinical Impact of Vitamin D in Children With Atopic Dermatitis

© Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology • The Korean Academy of Pediatric Allergy and Respiratory Disease http://e-aair.org Recently there have been a number of reports that vitamin D plays a role in the pathogenesis of many diseases including atopic dermatitis (AD). Considering the purported immunologic mechanisms that contribute to AD, it is possible that vitamin D may influence this disorder through its immunomodulatory properties. It was well known the active form of vitamin D [1,25(OH)2 D3] enhanced expression of antibacterial peptides, and prevented skin infections. Some studies demonstrated a link between vitamin D–mediated activation of Toll-like receptors, the production of cathelicidin, and diminished sensitivity to bacterial infections. In addition, vitamin D stimulates protein synthesis, such as filaggrin, that is necessary for stratum corneum barrier formation. Therefore, vitamin D deficiency might exacerbate AD via disturbed epidermal barrier function and immunologic dysregulation, with subsequent impaired defense against infections. Clinical observations indicate that the disease usually worsens in winter season as a result of less exposure to solar radiation. Epidemiologic investigations have shown a higher prevalence of AD in countries with higher geographic latitude. This is consistent with other observations that inhabitants of urban countries at high latitudes often have low vitamin D levels. Javanbakht et al revealed that additional factors, besides geographic locations, may influence vitamin D level in patients with AD. Lee’s study in this issue found an inverse correlation between serum concentration of vitamin D and severity of the disease expressed by SCORAD index in children with AD associated with food allergy. The result from this study also did not prove such a correlation in SCORAD index and any of its parameters and it could be explained by the influence of other environmental factors on the course of the disease. Perhaps other extrinsic factors, such as sweat or clothing, can irritate and exacerbate skin inflammation in a setting of low vitamin D levels. The deficiency of vitamin D is responsible for the most intensive skin lesions localized on body regions not exposed to sun. Vitamin D The Clinical Impact of Vitamin D in Children With Atopic Dermatitis