Vitamin D supplementation falls short in asthma prevention in at-risk kids

Supplementation with vitamin D during the perinatal period appears to have neutral effect on the 6-year incidence of asthma and recurrent wheeze among at-risk children, a study has shown.

A total of 806 women (mean age at baseline, 27.3 years) had been randomized to receive vitamin D3 at 4,400 IU (vitamin D group; n=405) or 400 IU (control group; n=401) per day during pregnancy. The primary outcome was the incidence of asthma and recurrent wheeze in offspring at the age of 6 years.

The primary outcome occurred in 176 children (43.5 percent) in the vitamin D group and 184 (45.9 percent) in the control group. Overall, 198 children (55.0 percent) were diagnosed with asthma, and 344 (95.6 percent) had recurrent wheezing.

In either an intention-to-treat analysis or one stratified according to the maternal 25-hydroxyvitamin D level during pregnancy, maternal vitamin D supplementation exerted a null effect on asthma and recurrent wheeze, as well as on on most of the prespecified secondary outcomes (ie, eczema, allergic rhinitis or lower respiratory tract infection).

Likewise, prenatal vitamin D supplementation did not improve spirometric indexes, although a very small effect on airway resistance (measured using impulse oscillometry) was seen. The significance of this benefit was uncertain.

The researchers pointed out that the effect of prenatal supplementation on airway resistance suggests a possible prenatal programming of lung airways and should be validated in future studies.