Lack of vitamin D is a global health problem that increases mortality rates. At this point, many studies have shown that having adequate amounts of vitamin D in the blood can lower your risk of cardiovascular disease, which is the leading cause of death. In a new review article that is published in Nutrients, the authors look closer at vitamin D supplementation to see if it can prevent stroke and speed up rehabilitation. It is essential that vitamin D supplements have good bioavailability so they can optimize blood levels of the nutrient.