VDR and Stroke: Identification of vitamin D receptors in the heart and vascular endothelial cells raised interest in the potential cardiovascular effects of vitamin D. Although several epidemiological studies have suggested that persons with low blood levels of vitamin D have increased risks of heart disease, stroke, and hypertension [22–25], meta-analyses and randomized controlled trials of vitamin D supplementation have failed to show cardiovascular benefits of this vitamin [26, 27].