The link between serum vitamin D level, sensitization to food allergens, and the severity of atopic dermatitis in infancy.

OBJECTIVE To investigate the association between serum vitamin D levels, sensitization to food allergens, and the severity of atopic dermatitis in infants. STUDY DESIGN We investigated serum 25-hydroxyvitamin D (25[OH]D) and specific immunoglobulin E levels to common or suspected food allergens in 226 infants with atopic dermatitis or food allergy. The severity of atopic dermatitis by the Scoring Atopic Dermatitis index and amount of vitamin D intake was measured in subcohort children. Sensitization to food allergen was categorized by the number (non-, mono-, and poly-) of sensitized allergens and the degree (undetected-, low-, and high-level) of sensitization. RESULTS Significant differences in 25(OH)D levels were found between groups on number (P = .006) and degree (P = .005) of food sensitization. The polysensitization group had significantly lower levels of 25(OH)D than the nonsensitization (P = .001) and monosensitization (P = .023) group. High-level sensitization group had significantly lower 25(OH)D levels compared with undetected (P = .005) and low-level (P = .009) sensitization group. Vitamin D deficiency increased the risk of sensitization to food allergens (OR 5.0; 95% CI 1.8-14.1), especially to milk (OR 10.4; 95% CI 3.3-32.7) and wheat (OR 4.2; 95% CI 1.1-15.8). In addition, the Scoring Atopic Dermatitis index was independently related to 25(OH)D levels after adjusting for the level of sensitization (adjusted R(2) = 0.112, P = .031). CONCLUSIONS Our results suggest that vitamin D deficiency increases the risk of sensitization to food allergens and that atopic dermatitis may be more severe in infants with vitamin D deficiency.