Background/Aims: Historically, research on vitamin D deficiency in young children focussed on bone development and rickets. Growing awareness of the immunomodulatory effects of vitamin D has led to the investigation of the relations of vitamin D status to many allergic diseases. Our objective was to investigate this topic in preschool-aged children in NZ.
Methods: 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. Modules of the validated International Study of Asthma and Allergies in Childhood questionnaire were used to identify eczema, allergic rhinoconjunctivitis (ARC) and asthma; diagnosis of doctor-diagnosed food allergy was by parental report. Analysis was by multivariable logistic regression.
Results: Mean 25(OH)D concentration was 52 (SD 19) nmol/L, with 7% of children <25nmol/L and 49% <50nmol/L. Children with 25(OH)D concentrations ≥75nmol/L (n=29) had a two-fold increased risk for parent-report of doctor-diagnosed food allergy compared to children with 25(OH)D 50-74nmol/L (OR=2.21, 1.33-3.68, P=0.002). There was a non-significant U-shaped association between 25(OH)D and ARC, with a nadir at approximately 60nmol/L. No associations were present between 25(OH)D concentration and presence of parent-reported eczema or asthma.
Conclusions: Vitamin D deficiency was not associated with several allergic diseases in these NZ preschool children. In contrast, high 25(OH)D concentrations were associated with a two-fold increased risk of food allergy, with a trend of higher risk of ARC following a U-shaped association with 25(OH)D.
Funding source: Health Research Council of New Zealand