Vitamin D deficiency is fairly common. Vitamin D is not actually a vitamin, but a hormone the body produces from sunlight.
According to a review of existing research there is evidence low vitamin D levels impact cardiovascular disease risk, specifically blood pressure, insulin resistance, and coronary artery disease. The review of around 75 mostly observational studies was published in the Journal of the American College of Cardiology.
Whether or not taking supplemental vitamin D will reduce cardiovascular risks or how much is needed to be effective is still to be determined. We now need more randomized control research studies to examine the impact of high dose Vitamin D supplementation to weigh the pros against the cons.
Daily Vitamin D Recommendation