The Relationship between Vitamin D Status and Allergic Diseases in New Zealand Preschool Children.

Recent research on vitamin D in young children has expanded from bone development to exploring immunomodulatory effects. Our aim was to investigate the relationship of vitamin D status and allergic diseases in preschool-aged children in New Zealand. Dried capillary blood spots were collected from 1329 children during late-winter to early-spring for 25(OH)D measurement by LC-MS/MS. Caregivers completed a questionnaire about their child's recent medical history. Analysis was by multivariable logistic regression. Mean 25(OH)D concentration was 52(SD19) nmol/L, with 7% of children <25 nmol/L and 49% <50 nmol/L. Children with 25(OH)D concentrations >= 75 nmol/L (n = 29) had a two-fold increased risk for parent-report of doctor-diagnosed food allergy compared to children with 25(OH)D 50-74.9 nmol/L (OR = 2.21, 1.33-3.68, p = 0.002). No associations were present between 25(OH)D concentration and presence of parent-reported eczema, allergic rhinoconjunctivitis or atopic asthma. Vitamin D deficiency was not associated with several allergic diseases in these New Zealand preschool children. In contrast, high 25(OH)D concentrations were associated with a two-fold increased risk of parental-report food allergy. This increase supports further research into the association between vitamin D status and allergic disease in preschool children.