A recent meta-analysis investigated the evidence regarding the effects of vitamin D supplements on the rate of asthma exacerbations.
Asthma is a long-term condition of the lungs. It is a condition where a person’s airways become narrow and inflamed, which makes breathing difficult. Asthma is a common condition that affects over 300 million people across the globe, and it is estimated to cause approximately 400,000 deaths each year. Mortality rates associated with asthma are often a result of episodes of acute exacerbations, which simply means asthma symptoms worsen. These exacerbations are often precipitated by viral upper respiratory infections. Vitamin D supplements have been shown to support the antiviral responses in respiratory epithelial cells and inhibit a pro-inflammatory marker which is isolated from the cells of patients with severe asthma.
This recent meta-analysis of data from 955 participants of seven randomised control trials provides an up to date overview of the protective effects of vitamin D supplements against asthma exacerbations needing treatment with systemic corticosteroids. This meta-analysis is novel as it also investigates if the effect of vitamin D on the risk of asthma exacerbation differs according to the pre-existing concentrations of vitamin D in patients.
The results of this meta-analysis showed that the rate of asthma exacerbations treated with systemic corticosteroids was reduced by vitamin D when compared with a placebo. A subgroup analysis demonstrated that vitamin D decreased the rate of asthma exacerbations treated with systemic corticosteroids in individuals with a baseline level of vitamin D (or 25-hydroxyvitamin D) below 25nmol/L. However, the results did not show that vitamin D had a statistically significant reduction in the rate of asthma exacerbations in individuals with a pre-existing vitamin D level of 25nmol/L or higher.
The authors of this meta-analysis, published in The Lancet Respiratory Medicine, conclude that their results reaffirm a previous meta-analysis demonstrating that vitamin D supplementation safely decreases the rate of asthma exacerbations. Despite these findings, the authors were unable to obtain any evidence that vitamin D’s effects differed between subgroups of patients.
Vitamin D supplementation is relatively cheap and asthma exacerbations are a major economic cost burden. This means that vitamin D could provide a new cost-effective strategy to decrease exacerbations and thus decrease this crucial cause of morbidity and mortality is asthmatic patients.
Written by Jade Marie Evans, MPharm, Medical Writer
Reference: Jolliffe.D et al. (2017). Vitamin D supplementation to prevent asthma exacerbations: a systematic review and meta-analysis of individual participant data. Available: http://www.thelancet.com/journals/lanres/article/PIIS2213-2600(17)30306-5/fulltext. Last accessed 19th Dec 2017 .