Vitamin D Does Not Effectively Help Asthma Symptom Management

In 2016, a Cochrane Review by Martineau and colleagues found that vitamin D reduced the risk of asthma exacerbation.¹ But the results of their study did not end the debate around the association between vitamin D supplementation and asthma. And so, nearly 7 years later, several authors from the initial Cochrane review published an update to their original study. In their updated Cochrane Review, the authors found that there was no evidence to support that vitamin D supplementation reduces asthma exacerbations.²

The researchers included double-blind, randomized, placebo-controlled studies in their review where they evaluated the effects of vitamin D in exacerbation risk and/or asthma symptom control in children and adults with asthma.

In total, the authors included 20 studies for their review. Of the total, 15 trials involved 1155 pediatric patients and five involved 1070 adults. Both the children and adults in the studies had mild to moderate asthma. The participants' ages ranged from 1 to 84 years.

Compared with participants who received placebo, participants who received vitamin D supplements did not have a lower risk of asthma attacks. Further, vitamin D did not affect asthma control or risk of harmful side effects.

As noted, the study had several limitations including the lack of representation of people with severe asthma and individuals with very low vitamin D levels prior to taking the supplement.

Despite the results of their updated review, the authors noted that further study on patient with severe asthma is still warranted. 

“In contrast to findings of our previous Cochrane Review on this topic, this updated review does not find evidence to support a role for vitamin D supplementation or its hydroxylated metabolites to reduce risk of asthma exacerbations or improve asthma control,” the researchers concluded. “Participants with severe asthma and those with baseline 25(OH)D concentrations < 25 nmol/L were poorly represented, so further research is warranted here. A single study investigating effects of calcidiol yielded positive results, so further studies investigating effects of this metabolite are needed.”

Reference:

1. Martineau AR, Cates CJ, Urashima M, et al. Vitamin D for the management of asthma. Cochrane Database Syst Rev. Published online September 5, 2016. doi: 10.1002/14651858.CD011511.pub2
2. Williamson A, Martineau AR, Sheikh A, Jolliffe D, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database Syst Rev. Published online February 6, 2023. doi:10.1002/14651858.CD011511.pub3