Evidence for efficiency of daily exposition to the sun or sun light source or intake of vitamin D3

GrassRootsHealth

http://www.bmj.com/content/356/bmj.i6583

http://www.foodmanufacture.co.uk/Ingredients/Vitamin-D-cold-and-flu-study-link-divides-scientists/?utm_source=Newsletter_Subject&utm_medium=email&utm_campaign=Newsletter%2BSubject&c=dC5HnbRQjqmLldPh8taGdocbYZm7sM2e