Some studies—both observational and randomized—have teased a potential link between vitamin D deficiency in mothers or infants and later development of atopic diseases. But those results have been inconsistent.
So investigators in Finland performed a large randomized controlled trial (RCT) to, hopefully, definitively answer this question.[1] Almost 1000 full-term infants were enrolled. The babies were given either 10 µg (400 IU) or 30 µg (1200 IU) daily vitamin D during the first 12 months of life. Concentrations of vitamin D [25(OH)D] were measured during pregnancy, in cord blood at the time of birth, and at 12 months of age.
Infants were evaluated at 1 year of age. Specific IgE antibodies toward common food and airborne allergens were measured. Parents completed questionnaires that asked whether their child had ever received a diagnosis of food allergies, eczema, or asthma or had ever been hospitalized for asthma or bronchiolitis. Additional questions asked about the presence of such symptoms as wheezing, cough, and rash. Finally, the researchers calculated dietary intake of vitamin D on the basis of a food questionnaire.
Over 90% of the infants completed the 12-month follow-up visit. The majority (79%) were breastfed for more than 6 months (average duration, 10.7 months).
