The association of vitamin D with allergy and lung function in asthmatic and healthy adolescents

Abstract

Background.Hypovitaminosis D is becoming an important public health problem everywhere, even in sunny parts of Europe. The role of vitamin D in skeletal disease is well-known but evidence suggests it might also be implicated in asthma and allergies.Objectives: To investigate the association of Vitamin D with allergic sensitization and lung function in asthmatic and non-asthmatic individuals.Methods.All reporting current wheezing on the ISAAC questionnaire among 538 4 16-18 year old Cypriot adolescents (65% response) were grouped into active asthmatics (CWA), if also reported asthma diagnosis (N = 69), and current wheezers only (CWO, N = 121). Controls were sampled amongst Never Wheezers/ Never Asthmatics (NWNA, N = 671, 75% response). Measures included serum 25(OH)D, lung function using spirometry (FEV1 and FVC) and skin prick testing to 8 aeroallergens. The association of vitamin D with study outcomes in each group was investigated in regression models.Results Vitamin D deficiency (< 20 ng/ml) and insufficiency (<30 ng/ml) were associated with allergic sensitization among wheezers. Those with vitamin D insufficiency were almost 4-times more likely to be sensitized to at least one allergen (OR 3.83, 95% CI = 1.23-11.96) after adjusting for seasonality and family history of allergy. Prevalence of polysensitization (positive >3 allergens) appeared 3–4 times higher among wheezers and NWNA with vitamin D insufficiency, even though associations were short of statistical significance due to the small number of participants in the vitamin D sufficiency range (only one in 10). In contrast, only a weak correlation was observed between Vitamin D and FVC in CWA (>0.27, p = 0.09) while no association was observed with lung function measures in the other groups.Conclusions.The results suggest a possible link between vitamin D and allergic sensitization against a background of mixed findings of mainly cross-sectional and only two prospective studies in the literature.