People who boost their vitamin D levels with supplements reduce their risk of respiratory tract infections, such as the flu, by up to 12%, according to a new systematic review and meta-analysis study of 25 randomized controlled trial (RCT) studies published in The BMJ.
https://bcmj.org/news/vitamin-d-effective-reducing-flu-and-c...
Harvard Gazette: Study confirms vitamin D protects against colds and flu
https://news.harvard.edu/gazette/story/2017/02/study-confirm...
WebMD: Vitamin D May Cut Risk of Flu
https://www.webmd.com/cold-and-flu/news/20100616/vitamin-d-m...
Vitamin D protects against colds and flu, finds major global study https://www.sciencedaily.com/releases/2017/02/170216110002.h...