‘Cracking the Aging Code' with vitamin D, Metformin, etc. Book
'Cracking the Aging Code' Says Halting Aging Process Possible Via Vitamin D, Metformin, Anti-Parkinson Drug Intake
Kindle $15, Look inside, free preview
A quick look inside the book from Amazon: Vitamin D decreases death rate
See also VitaminDWiki
Mortality category listing has items along with related searches along with the following chart
People die sooner if they have low vitamin D
click on image for details