Effect of vitamin D supplementation on clinical outcomes of children with asthma and vitamin D deficiency Original paper

Asthma is a chronic inflammatory disease of the airway and is caused by increased sensitivity to allergens. New evidence suggests that vitamin D levels may be a factor in this disease. Vitamin D levels can have an impact on the immune system, and the epithelial cells lining the airways have high levels of enzymes that produce the active form of vitamin D. Recent studies have shown that supplementing with vitamin D during pregnancy can reduce the risk of childhood asthma, and vitamin D is known to affect pulmonary (lung) function and airway sensitivity. This study examined the effect of vitamin D supplements on clinical outcomes in children with asthma and vitamin D deficiency.

In a 12-week interventional study, the researchers assessed serum levels of vitamin D (25-hydroxyvitamin D), asthma severity, and lung function before and after therapeutic vitamin D was prescribed. The 68 children who participated in the study had an average age of 10.7 years, 39 of the participants were male, and 29 were female. Participants with vitamin D levels below 10 ng/ml received one of a few different vitamin D treatments: 3200 IU per day for 12 weeks for the 12-week intervention, one 50,000 IU tablet a day for up to 6 days, or 300,000 IU via intramuscular injection once per month. For patients with vitamin D levels of 10-30 ng/ml, vitamin D was administered based on the participant’s calcium level.

Asthma severity decreased after the vitamin D intervention, as did several indicators of lung function (forced expiratory volume in 1 second, forced vital capacity, and FEV1-to-FVC ratio), indicating that lung function improved. The authors concluded that therapeutic vitamin D is “very effective“ in improving asthma in children.

We have several qualms about this study. The authors’ description of the treatments was vague and nondescriptive, with no information on the amounts of vitamin D given to patients with vitamin D insufficiency. All patients improved after the intervention, which the authors’ attributed to vitamin D supplementation, but without a placebo control group and appropriate blinding, we can’t know. Although other more rigorous research has been published suggesting that vitamin D supplementation may improve asthma control in people with low vitamin D levels, the current study does not add to this body of work.