title: Serum micronutrient concentrations and childhood asthma: the PIAMA birth cohort study.
abstract: BACKGROUND
  Research suggests an influence of micronutrients on childhood asthma. So far, evidence mainly originates from cross-sectional studies using nutrient intake data, which is not an accurate measure of nutrient status. This study aimed to investigate the cross-sectional and prospective associations between serum concentrations of magnesium, vitamin D, selenium, and zinc and prevalence of (severe) asthma, atopy, and bronchial hyperresponsiveness (BHR) in childhood.
  
  
  METHODS
  In the Prevention and Incidence of Asthma and Mite Allergy birth cohort study, serum nutrient concentrations were available for a 4-yr-old subgroup (n = 372) and for a different 8-yr-old subgroup (n = 328). Yearly questionnaires inquired about asthma prevalence until 8 yr of age. Allergic sensitization was measured at 4 and 8 yr of age; BHR was measured at 8 yr of age. Data were analyzed with logistic regression and generalized estimating equations models.
  
  
  RESULTS
  There was a consistent (non-significant) inverse association between serum magnesium concentrations and asthma prevalence. Serum vitamin D concentrations measured at age 4 were inversely associated with asthma at ages 4-8 [e.g., cross-sectional association between vitamin D tertile 3 vs. 1 and severe asthma: odds ratio (OR): 0.49, 95% confidence interval (CI): 0.25-0.95], whereas vitamin D measured at age 8 was positively associated with asthma at age 8 (e.g., cross-sectional association between vitamin D tertile 3 vs. 1 and severe asthma: OR: 2.14, 95% CI: 0.67-6.82).
  
  
  CONCLUSIONS
  Our study contributes to the evidence that children with higher serum magnesium concentrations are less likely to have asthma. The associations between serum vitamin D concentrations and asthma were age-dependent.
authors.affiliation: Department of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: A A M
authors.initials: AA
authors.lastname: van Oeffelen
authors.forename: M B M
authors.initials: MB
authors.lastname: Bekkers
authors.forename: H A
authors.initials: HA
authors.lastname: Smit
authors.forename: M
authors.initials: M
authors.lastname: Kerkhof
authors.forename: G H
authors.initials: GH
authors.lastname: Koppelman
authors.forename: A
authors.initials: A
authors.lastname: Haveman-Nies
authors.forename: D L
authors.initials: DL
authors.lastname: van der A
authors.forename: E H J M
authors.initials: EH
authors.lastname: Jansen
authors.forename: A H
authors.initials: AH
authors.lastname: Wijga
mesh_terms: D000367:Age Factors; D001249:Asthma / Q000097:blood* / Q000453:epidemiology* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008274:Magnesium / Q000097:blood*; D008297:Male; D018977:Micronutrients / Q000097:blood*; D009426:Netherlands; D015995:Prevalence; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000097:blood*; D015032:Zinc / Q000097:blood*
chemical_list: D018977:Micronutrients; D014807:Vitamin D; D007073:Immunoglobulin E; D008274:Magnesium; D015032:Zinc