PURPOSE OF THE STUDY.
To examine the relationship between serum 25-hydroxyvitamin D (25[OH]D) levels and the prevalence of food and environmental allergies.
The study used the National Health and Nutrition Examination Survey 2005–2006, composed of a population of civilian noninstitutionalized US residents, which deliberately oversampled non-Hispanic black and Mexican American people to obtain accurate prevalence data in those subpopulations. All participants 1 year of age or older with available 25(OH)D levels and allergy-test results were included. Included in the final analysis were 3136 children and 3454 adults (>21 years old).
Information about vitamin D supplements, milk intake in the previous month (daily, less than daily but more than weekly, and once weekly or less), and television, computer, and videogame time (“screen time”) (none, <2 hours/day, 2–4 hours/day, and >4 hours/day) was collected. Allergy was determined by a questionnaire, and serum was obtained for total immunoglobulin E (IgE) and for specific IgE to dust mites, cat, dog, Alternaria, peanut, egg, and milk. Subjects 6 years of age or older also had ImmunoCAP (Phadia, Uppsala, Sweden) levels measured for German cockroach, selected tree, grass, and weed pollens, and shrimp. Allergy was defined as any positive IgE test result (≥0.35 kU/L) or a total IgE level in the top quintile (>191 kU/L). Seasonal and perennial allergies were defined as a positive ImmunoCAP level to a pollen or perennial allergen, respectively. 25(OH)D levels were classified as deficient (<15 ng/mL), insufficient (15–29 ng/mL), or sufficient (≥30 ng/mL).
Deficient 25(OH)D levels were associated with being non-Hispanic black or Mexican American, having a low socioeconomic status, >4 hours/day of screen time, lower frequency of milk-drinking, and not taking vitamin D supplements. Children and adolescents deficient in 25(OH)D had a higher prevalence of sensitization to most individual allergens, to any allergen, and to any seasonal or perennial allergen than those with insufficient or sufficient levels. The same trends were not seen in adults. Questionnaire data also revealed an association between deficient and insufficient 25(OH)D levels and prevalence of allergy symptoms in general but not to specific symptoms in children and adolescents.
Vitamin D deficiency is associated with a higher rate of allergic sensitization and self-reported allergy in children and adolescents.
Results of this study support previous ones in which low vitamin D levels were implicated in higher rates of allergic disease. The noncalcemic effects of vitamin D, including its immunomodulatory effects on antigen-presenting cells and effector cells, are growing areas of research, but specific mechanisms are not yet known. “Got milk?” Although there are no data as to whether vitamin D supplementation or naturally acquired higher 25(OH)D levels can reverse allergic sensitization, these results provide 1 more reason for children to turn off the video screen and go outside to play.
- Copyright © 2011 by the American Academy of Pediatrics