Randomized trial of vitamin D supplementation for winter-related atopic dermatitis in children.

Randomized placebo-controlled trial in Mongolian children with winter-related atopic dermatitis recruited from outpatient clinics in Ulaanbaatar during February to March 2009. The active vitamin D3 arm included participants aged 2 to 17 years.

Vitamin D3 was given as oral cholecalciferol, one drop providing 1000 IU daily for 1 month, compared with placebo. One-month follow-up data were available for 57 of the 58 participants randomized to the active arm.

Vitamin D3 improved winter-related atopic dermatitis compared with placebo, and no major or minor adverse events were reported. At 1 month, the average percent change in baseline EASI was 29% with vitamin D3 versus 16% with placebo (P = .02), and IGA also favored vitamin D3 (Fisher exact test P = .03; P for trend = .04). Parental assessment that the dermatitis was better than baseline was also significant at 1 month, 64% versus 43% (P = .03), but not at 2 weeks, 45% versus 33% (P = .24).

The trial was short, with only 1 month of follow-up, so durability of benefit is unknown. Generalizability is limited by the single-country, winter-season setting in Mongolian children from one urban clinic network, and some baseline diet data were not shown. The active arm was modest in size, which limits precision for safety and subgroup inferences.