The prevalence of wheezing and its association with serum zinc concentration in children and adolescents in Brazil

Objective: To assess the influence of zinc serum status on the prevalence of wheezing in a sample of children and adolescents in Northeastern Brazil. Research methods and procedures: This is a cross-sectional study which included 592 students of 6-12 years old, from the public elementary schools of Sao Francisco do Conde, Bahia, Northeastern Brazil. Report of wheezing in the past 12 months was collected using a questionnaire of the International Study of Asthma and Allergies in Childhood Program (ISAAC) phase III, adapted to Portuguese. The determination of serum Zn levels was performed using a flame atomic absorption spectrometer. Data on anthropometric status, level of physical activity, pubertal development and socioeconomic information, for each participant were obtained. Multivariate logistic regression analyses were used to assess the associations of interest. Results: Of the students, 8.6% (95% CI 6.30-10.9) reported having wheezing. The mean (SD) serum zinc level was 114 (22.9 mu g/dL). The results of the multiple logistic regression analysis showed, after adjustments, positive and significant association between low serum zinc levels and wheezing. Students categorized as being below the median for serum Zn concentration presented an almost 1.9-fold increase in the wheezing prevalence ratio (OR = 1.9; 95% CI 1.03-3.53). Conclusion: The main findings of this study suggest that the level of zinc may influence the risk of wheezing in late childhood on the study population. (C) 2014 Elsevier GmbH. All rights reserved.