Vitamin D Deficiency And Lung Function In Asthmatic Children

A new study from researchers in Boston has found that poorer lung function in asthmatic children, treated with inhaled corticosteroids, is linked with vitamin D deficiency.

Ann Chen Wu, MD, MPH, assistant professor in the Department of Population Medicine at Harvard

Medical School and Harvard Pilgrim Health Care Institute said:

"In our study of 1,024 children with mild to moderate persistent asthma, those who were deficient in vitamin D levels showed less improvement in pre-bronchodilator forced expiratory volume in 1 second (FEV1) after one year of treatment with inhaled corticosteroids than children with sufficient levels of vitamin D."

The study, which was published in American Journal of Respiratory and Critical Care Medicine, used data from the Childhood Asthma Management Program. It was a multi-center trial of asthmatic children between 5 and 12 years of age who were randomly assigned to treatment with nedocromil, budesonide (inhaled corticosteroid), or a placebo. The patients' vitamin D levels were categorized as deficient (≤ 20 ng/ml), insufficient (20-30 ng/ml), or sufficient (> 30 ng/ml).

Pre-bronchodilator FEV1 was increased during a treatment period of 12 months by 330 ml in the vitamin D insufficiency group that were treated with inhaled corticosteroids. In the vitamin D sufficiency group, kids with the same treatment saw a 290 ml increase, and in the vitamin D deficiency group only 140 ml increase.

Children who were vitamin D deficient were more likely to be African American, older, and have a higher BMI, as oppose to children who were vitamin D sufficient or insufficient. Those that were sufficient or insufficient in vitamin D, were associated with a more significant change in pre-bronchodilator FEV1 over 12 months of treatment after adjustment for age, race, gender, BMI, history of emergency visits, and time of year that the vitamin D specimen was taken.

The study had a few minor setbacks. Limitations included having only a small sample size of 101 vitamin D deficient children, and that the researchers only examined vitamin D levels at one time point.