Asthma control and exacerbations are not improved with the use of vitamin D according to the findings of an updated Cochrane systemic review
The use of vitamin D supplements has no overall effect on asthma control or in reducing the risk of a disease exacerbation according to the findings of an updated Cochrane systemic review.
Asthma is a chronic inflammatory respiratory disease and which globally, in 2019, was estimated to affect 262 million people in 2019, leading to 455,000 deaths. The potential role of vitamin D in asthma control is unclear though one study observed that among those deficient in the vitamin, the odds of having an exacerbation were 25% greater compared to those with levels in the normal range. Moreover, other work in children with severe, therapy-resistant asthma, found that lower vitamin D levels were linked to increased airway smooth muscle mass together with worse asthma control and lung function.
In 2016, a Cochrane review examined the possible value of vitamin D for the management of asthma and concluded that the vitamin is likely to reduce the risk of severe asthma exacerbations and healthcare. Despite this conclusion, the authors were uncertain as to whether these possible benefits were confined to those who had suboptimal vitamin D levels. The current review provided an updated meta-analysis based on subsequently published trials and included patients with mild to moderate asthma.
Asthma control and vitamin D use
A total of 20 studies, 15 of which included 1155 children and 5 with 1070 adults were included in the updated analysis. The researchers performed several subgroup analyses based on initial vitamin D status as well as the dosage and regime of the vitamin used.
Overall, use of vitamin D did not reduce or increase the proportion of patients who experienced one or more disease exacerbations requiring treatment with systemic corticosteroids (Odds ratio, OR = 1.04, 95% CI 0.81 – 1.34). In addition, vitamin D had no effect on the rate of asthma exacerbations and subgroup analysis failed to reveal any effect based on vitamin D status, dose, dosage frequency or patient age.
Secondary outcomes examined included exacerbations leading to hospitalisation and measures of asthma control but again, vitamin D had no impact on any of the assessed outcomes.
The authors concluded that in contrast to their 2016 review, the current analysis failed to identify any benefits from vitamin D supplementation on asthma exacerbations or asthma control.
Williamson A et al. Vitamin D for the management of asthma. Cochrane Database Sys Rev 2023