An article published in the December 9, 2008 issue of the Journal of the American College of Cardiology describes the cardiac risk factors associated with vitamin D deficiency. The study results showed that low vitamin D levels are directly related to cardiovascular disease (including high blood pressure, diabetes, and obesity).



Previous studies estimate that vitamin D deficiency affects up to half of all adults and 30 percent of children in the United States. While the vitamin’s role in bone health is well known, several recent studies have uncovered associations between deficient levels of the vitamin and a number of diseases, including cardiovascular disease.



In the review, Michael F. Holick, MD, PhD and colleagues report that vitamin D deficiency activates the renin-angiotensin-aldosterone system, which can lead to hypertension and thickening of the heart and blood vessel walls. Altered hormone levels related to a deficiency of the hormone vitamin D increase the risk of diabetes, which is a well known risk factor for the development of cardiovascular disease. In 15,088 subjects from the NHANES III national cohort registry, higher vitamin D levels were associated with a lower risk of diabetes as well as hypertension, high triglycerides, and obesity.



In addition, chronic vitamin D deficiency can result in secondary hyperparathyroidism, which increases the risk of inflammation and cardiovascular events. Elevated parathyroid levels were associated with an increased risk of death among older individuals compared to those with normal levels over the course of follow-up in a recent observational study.



Lead coauthor James H. O'Keefe, MD, who is a cardiologist and director of Preventive Cardiology at the Mid America Heart Institute in Kansas City, Missouri writes that insufficient exposure to sunlight causes vitamin D deficiency. This is exacerbated in people who are overweight because they can produce vitamin D efficiently.

The authors’ strategy for restoring vitamin D to optimal levels includes initial treatment with 50,000 international units (IU) vitamin D2 or D3 weekly for 8 to 12 weeks followed by maintenance with 1,000 to 2,000 IU daily. O’Keefe also suggests limited sun exposure as a means of increasing vitamin D levels. The researchers observed that supplementation with vitamin D is safe and that adverse effects such as elevated calcium levels and kidney stone development are only rarely seen in individuals who consume 20,000 IU per day or more of vitamin D3.