Researchers from Queen Mary University of London and the University of Edinburgh found no evidence of reduced asthma attacks with vitamin D supplementation. The study is published in the Cochrane Database of Systematic Reviews .
The scientists analyzed the results of 20 high-quality studies. A total of 1,155 children and 1,070 adults with asthma took part.
The review did not show any effect of vitamin D supplementation on asthma control, even if people were vitamin D deficient. The dose of the medication also did not matter. Most studies tested the effects of cholecalciferol, and one trial tested the effects of another form of vitamin D, calcidiol. This drug has somewhat reduced the frequency of asthma attacks, so the scientists recommend more research.
In addition, the researchers did not look at the benefit of vitamin D supplementation in severely deficient or severe asthma.
Some studies have previously shown that vitamin D deficiency is associated with an increased risk of severe asthma attacks. Among them was a previous review by the authors. It was published in 2016, and scientists acknowledge that much more data has emerged since then. The results of the new review can be prioritized as more high-quality studies are included.
Also, the contradiction between the two reviews may be explained by the fact that people have increased the use of vitamin D supplements in recent years, which has led to a decrease in the prevalence of its deficiency.
The authors’ results highlight the need to update reviews as new studies become available.