researchers have attributed a host of other functions to the vitamin, and one of these is supporting the immune system. A systematic review and meta-analysis from 2017 in BMJ drew on data from 25 randomized controlled trials to look at whether taking a vitamin D supplement could prevent acute respiratory tract infections.
The international research consortium, led by Prof. Adrian R. Martineau, from the Centre for Primary Care and Public Health and the Asthma UK Centre for Applied Research, at Queen Mary University of London, in the United Kingdom, looked at data from nearly 11,000 study participants.