title: Outdoor exposure and vitamin D levels in urban children with asthma.
abstract: BACKGROUND
  The inner-city pediatric population in the United States has a disproportionate burden of asthma. Recent attention has focused on the immunomodulatory role of vitamin D, which may be protective against disease morbidity. As the primary determinant of vitamin D status in humans is exposure to sunlight, we aimed to determine if 25-OH vitamin D levels in urban preschool children with asthma were low, influenced by time spent outdoors, and associated with asthma morbidity.
  
  
  METHODS
  Serum 25-OH vitamin D levels were measured at baseline in a cohort of 121 inner-city children ages 2-6 years with asthma in Baltimore, MD. Participants were followed longitudinally at 3 and 6 months to assess time spent outdoors, asthma symptoms through questionnaires and daily diaries, and allergic markers.
  
  
  RESULTS
  In a predominantly black population of preschool children, the median 25-OH vitamin D level was 28 ng/mL (IQR 21.2-36.9), with 54% of the children below the traditionally sufficient level of 30 ng/mL and 7.4% in the range associated with risk of rickets (< 15 ng/mL). The median time spent outdoors was 3 hours/day (IQR 2-4), and greater time spent outdoors was not associated with higher vitamin D levels. 25-OH vitamin D did not show seasonal variation in our cohort (p = 0.66). Lower 25-OH levels were correlated with higher IgE levels.
  
  
  CONCLUSIONS
  Urban African-American preschool children with asthma have high rates of vitamin D insufficiency, and increased outdoor exposure is unlikely to correct these low 25-OH vitamin D levels. Repletion in this population may require dietary supplementation.
authors.forename: Sonali
authors.initials: S
authors.lastname: Bose
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Breysse
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Hansel
authors.forename: Robert R
authors.initials: RR
authors.lastname: Rusher
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Matsui
authors.forename: Roger
authors.initials: R
authors.lastname: Peng
authors.forename: Jean
authors.initials: J
authors.lastname: Curtin-Brosnan
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Diette
mesh_terms: D001741:Black or African American; D001249:Asthma / Q000097:blood / Q000453:epidemiology*; D015142:Baltimore; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D015995:Prevalence; D011446:Prospective Studies; D012044:Regression Analysis; D012621:Seasons; D013472:Sunlight; D011795:Surveys and Questionnaires; D014505:Urban Population; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
chemical_list: D014807:Vitamin D