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

Randomized, double-blind, placebo-controlled trial in Mongolian children aged 2–17 years with winter-related atopic dermatitis (baseline EASI 10–72; mean 21, SD 9). 107 participants randomized (58 to vitamin D, 49 to placebo) across dermatology clinics in Ulaanbaatar; 59% male; AD history common.

Oral cholecalciferol (Vitamin D3) 1000 IU daily for 1 month.

Vitamin D3 supplementation for 1 month produced a clinically and statistically significant improvement in disease severity vs placebo: EASI score improved more with vitamin D (P=0.01) and Investigator’s Global Assessment favored vitamin D (P=0.03). No major adverse events occurred. Conclusion: Short-term oral vitamin D supplementation improves winter-related atopic dermatitis in children, supporting assessment of vitamin D status and consideration of supplementation in similar high-latitude settings.

Limitations: short duration (1 month); small sample; no measurement of serum 25(OH)D to relate baseline status or response; generalizability limited to Mongolian children with winter-related AD; longer-term safety/efficacy not assessed.