German researchers conducted a prospective cohort study on 3,316 white patients who were scheduled to undergo coronary angiography between 1997 and 2000. Vitamin D levels were measured and recorded on 3,299 of these patients for later analysis. During the follow-up period, 42 patients suffered a fatal stroke. The risk of fatal stroke was then determined for various vitamin D levels.
The patients who died from strokes were found to have significantly lower vitamin D levels than both the stroke survivors and those who did not experience a stroke during the follow up period. This trend remained significant even after adjustments were made for multiple outside variables such as exercise and cardiovascular disease markers. The researchers conclude that vitamin D might directly protect against stroke. They also conclude that vitamin D supplements are a promising and preventative/therapeutic approach in patients after stroke and at high risk for future stroke.
Pilz, Stefan et al. Stroke. July 2008;39:2611.