NEW YORK (Reuters Health) – The results of a small study suggest that supplementation with vitamin D can restore production of an antimicrobial peptide in patients with atopic dermatitis, thereby decreasing their risk of skin infections.

Atopic dermatitis patients are known to be at increased risk for cutaneous infections with Staphylococcus aureus, herpes simplex, and other pathogens, Dr. Tissa R. Hata and colleagues, from the University of California, San Diego in La Jolla, note in a letter in the Journal of Allergy and Clinical Immunology for October 3. Recent findings suggest that this may relate to a deficit in the innate immune response, specifically an inability to ramp up production of the antimicrobial peptide cathelicidin.

Examination of the cathelicidin gene has shown that it contains a vitamin D response element in its promoter, according to the report.

In their study, which involved 14 patients with moderate to severe atopic dermatitis and 14 normal controls, the researchers examined whether oral vitamin D 4000 IU/day for 3 weeks could enhance cathelicidin expression in the skin.

Analysis of biopsy samples showed that vitamin D use markedly increased cathelicidin expression in affected skin from dermatitis patients. Skin from controls and unaffected skin from dermatitis patients also showed increased cathelicidin expression, but not to the extent seen in affected skin.

“Larger studies examining the incidence and risks of infections in atopic subjects while on vitamin D supplementation, and supplementation for a longer duration, will be necessary in the future to see if this increase in cathelicidin is adequate in the prevention of infections in these patients,” the authors state.

J Allergy Clin Immunol 2008;122:829-831.