Modulatory role of vitamin D in atopic dermatitis and allergic rhinitis

Abstract

Vitamin D, beyond its classical role in calcium homeostasis, has emerged as a key regulator of immune function and epithelial barrier integrity. Its deficiency during early childhood—a critical period for immune maturation—has been increasingly implicated in the development of atopic diseases. While extensively studied in asthma, its role in non-respiratory allergic conditions such as atopic dermatitis (AD) and allergic rhinitis (AR) remains comparatively underexplored. This minireview synthesizes current mechanistic and clinical evidence on vitamin D in pediatric AD and AR. In AD, vitamin D promotes epidermal barrier function through upregulation of filaggrin and ceramide synthesis, and enhances antimicrobial defense via induction of antimicrobial peptides. Observational studies consistently report lower serum 25-hydroxyvitamin D in affected children, particularly those with allergic sensitization. Select randomized controlled trials suggest clinical improvement with supplementation, especially at doses > 2000 IU/day in deficient individuals. In AR, epidemiological data indicate stronger inverse associations with seasonal (pollen-induced) disease. Proposed mechanisms include modulation of dendritic cells, regulatory T cells, T helper 2 cytokines, and mucosal barrier integrity. The shared immunopathogenesis of AD and AR underscores vitamin D’s relevance. Although promising, clinical evidence remains heterogeneous. Future research should prioritize phenotype-stratified trials to clarify optimal dosing, timing, and individual response determinants, including genetics and microbiome composition.

Keywords: Vitamin D; Atopic dermatitis; Allergic rhinitis; Pediatric allergy; Immune modulation; Epithelial barrier function; Vitamin D receptor; Allergic sensitization; Early-life immunity; Genetic polymorphism

Core Tip: Vitamin D has emerged as a key modulator of immune responses and epithelial barrier integrity relevant to pediatric atopic dermatitis and allergic rhinitis (AR). Recent evidence highlights phenotype-specific effects, particularly in children with allergic sensitization, and suggests stronger associations with seasonal AR. Advances in vitamin D receptor biology and genomics support a personalized approach to supplementation. Early-life vitamin D exposure may influence immune development and disease trajectory, underscoring the potential for preventive and therapeutic applications in pediatric allergy care.