PURPOSE OF THE STUDY.
To determine whether vitamin D supplementation during pregnancy and infancy prevents aeroallergen sensitization and respiratory illness identified by primary care providers.
Two hundred and sixty women were recruited from an urban primary care maternity clinic in New Zealand from April 2010 to July 2011. The women were managed from 27 weeks’ gestation to delivery, and their infants were managed from birth to 18 months of age. Participants were not taking vitamin D supplementation before enrollment.
This was a randomized, double-blind, placebo-controlled, parallel-group trial. The mother and infant pairs were randomly assigned to daily placebo and placebo, lower-dose vitamin D (1000 IU/day for mother; 400 IU/day for infant), or higher-dose vitamin D (2000 IU/day; 800 IU/day). When the children were 18 months of age, skin prick testing and specific immunoglobulin E (IgE) antibodies were measured to common aeroallergens including house dust mites (such as Dermatophagoides farinae and Dermatophagoides pteronyssinus), cats, and grass pollen. In addition, serum 25-hydroxyvitamin D concentration was measured, and primary care visits were reviewed to assess the incidence of acute respiratory illnesses among the treatment groups.
Skin prick tests for the selected aeroallergens were available for 184 out of 186 children from whom serum was also collected at 18 months of age. Less than 5% of children had measurable specific IgE to aeroallergens other than dust mites. As a result, group comparisons were made for the mite antigen groups only. For the skin prick testing, children who received higher-dose vitamin D supplementation had a reduced risk of mite antigen sensitization (P = .03). The proportion of children with serum-specific IgE positivity to dust mites was significantly decreased for both low-dose and high-dose vitamin D supplementation. In regard to primary care visits, the number of children presenting with asthma and in whom asthma was listed as a diagnosis was significantly smaller in the groups receiving vitamin D supplementation.
Vitamin D supplementation during the third trimester and first 6 months of life decreases sensitization to house dust mites and the number of primary care visits for asthma at the age of 18 months.
Vitamin D has immune-modulating effects, and it is known that atopic sensitization can start before birth. The authors of this study suggest that early vitamin D supplementation in utero and in early infancy can decrease the sensitization to dust mites later in life. These results are especially important for populations at risk for vitamin D deficiency, such as in breastfed infants. Current guidelines recommend supplementation with 400 IU per day, yet the authors of this study suggest that a higher dose of 800 IU per day may decrease infants’ sensitization to house dust mites. Further studies are needed to determine optimum doses and durations of vitamin D supplementation as a possible allergy prevention measure.
- Copyright © 2017 by the American Academy of Pediatrics