Complex relationships between vitamin D and allergic sensitization among Puerto Rican 2-year-old children.

Background: In the United States, Puerto Ricans have a higher prevalence of asthma than other Latino ethnicities. Low vitamin D levels for children living in northern climates could be a factor.

Objective: To assess serum 25-hydroxyvitamin D [25(OH)D] distributions (a marker of vitamin D) and associations among vitamin D, allergic sensitization, early wheeze, and home/demographic factors.

Methods: Puerto Rican infants born in New York City, with a maternal history of atopy, were enrolled in a birth cohort. Blood was collected at age 2 years (n = 154; 82 males and 72 females). Serum 25(OH)D and immunoglobulin E (IgE) (indoor allergen-specific and total) were determined using immunoassays. Home/demographic characteristics and respiratory symptoms were assessed by questionnaire.

Results: The median concentration of 25(OH)D was 22.6 ng/mL; 32% were at risk of deficiency or inadequacy (<12 or 12-19 ng/mL). Serum 25(OH)D levels were lower in the heating (a surrogate for less sun exposure in colder months) compared with nonheating (26.1 vs 22.7 ng/mL, P = .02) season, but were not associated with allergen-specific IgE levels or with level of acculturation (measured by maternal birthplace). However, low 25(OH)D levels (below median) were associated with high total IgE >100 IU/mL (P = .01). Also, 25(OH)D concentrations differed between children who attended daycare and those who did not (21.8 vs 24.5 ng/mL; t test, P = .02). Serum 25(OH)D was not associated with wheeze or asthma by 2 years of age (P = .43).

Conclusion: Vitamin D deficiency, possibly linked with allergic pathways, may partially explain the trajectory for disproportionate asthma burden among Puerto Ricans, especially those born and raised in colder climates.