> Vitamin D has been endlessly promoted as a treatment for many diseases due to evidence from observational studies, but hundreds of millions of dollars in rand

> Vitamin D has been endlessly promoted as a treatment for many diseases due to evidence from observational studies, but hundreds of millions of dollars in randomized controlled trials have never demonstrated it to be effective for any disease except rickets. This randomized controlled trial, with 11000 participants "confirms vitamin D protects against colds and flu": https://news.harvard.edu/gazette/story/2017/02/study-confirms-vitamin-d-protects-against-cold-and-flu/ https://news.harvard.edu/gazette/story/2017/02/study-confirm...