Taking vitamin D supplements does not decrease the risk of asthma attacks, not in children nor adults, according to an updated Cochrane review, which previously suggested a reduction in asthma attacks in people taking vitamin D.
In this analysis, the researchers assessed 20 randomized controlled trials consisting of 1,155 children, and 1,070 adults with asthma. The data compared to nine trials comprised total of 1,093 people from a previous review. The majority of patients in the trials had mild to moderate asthma.
According to the results, when comparing patients who were assigned to take a vitamin D supplement with patients who were assigned to a placebo arm, the researchers found no statistically discernible difference in the number of people who experienced an asthma attack requiring treatment with a course of steroid tablets. Overall, the researchers did not observe any effect of taking vitamin D on asthma control.
“Vitamin D deficiency has been linked to an increased risk of severe asthma attacks and our previous Cochrane review, published in 2016, found that vitamin D reduced the risk of asthma attacks. However, more studies have been published since then and when we included the extra data in our updated review, the overall results changed. We found that vitamin D supplements had no effect on risk of asthma attacks or on control of asthma symptoms compared with a placebo,” said researcher Adrian Martineau, Clinical Professor of Respiratory Infection and Immunity at Queen Mary University of London, via a press release about the study.
Professor Martineau added that: “In contrast to our previous Cochrane review on this topic, this updated review does not find that vitamin D offers protection against asthma attacks or improves control of asthma symptoms. However, the trials we looked at did not include many people with severe asthma or people with very low levels of vitamin D in their blood, so these are areas where more research is still needed.