Selenium status and allergic disease in a cohort of New Zealand children

Background New Zealand has one of the highest rates of asthma and atopy. Selenium has been implicated in the aetiology of asthma, and associations between low selenium status and asthma in New Zealand children have been reported. Objective The aim was to investigate the association between selenium status and allergic disease in a birth cohort of New Zealand children. Methods The New Zealand Asthma and Allergy Cohort Study is a prospective birth cohort in Wellington and Christchurch, involving 1105 infants born 1997-2001. During the 6year assessment (n = 635), associations were investigated between plasma selenium (PlSe) and whole blood glutathione peroxidase activity (WBGPx) and allergy-related health outcomes including asthma, wheeze, hayfever, rhinitis, eczema and rash. Results Wellington children had greater PlSe and WBGPx than Christchurch children (P < 0.001 for both). PlSe (P = 0.004) and WBGPx (P = 0.03) were lower in children exposed to environmental smoke, but differences were no longer significant after adjustment for study location, current household smoking (5-6 years), maternal smoking during pregnancy, family history (either parent with asthma, eczema or hayfever), prioritized ethnicity (Maori, Pacific peoples, Other, European), gender, season born, number of siblings, New Zealand Deprivation Index and body mass index at 6 years. Analysis of PlSe or WBGPx as continuous variables or of quartiles of PlSe with health outcomes showed no significant associations after adjustment. Univariate analysis of quartiles of PlSe and WBGPx with persistent wheeze showed significant inverse trends (P = 0.005 for both), but these reduced after adjustment. Conclusions and Clinical Relevance Our results do not support a strong association between selenium status and the high incidence of asthma in New Zealand. However, there was a modest association between lower PlSe and WBGPx activity and higher incidence of persistent wheeze.