Written by Patrick Massey M.D., Ph.D. Research shows that vitamin D may reduce your risk of heart disease.
Can a daily dose of vitamin D reduce your risk of heart disease? This was the question asked by a group of researchers at Harvard School of Public Health and the departments of medicine at both Brigham and Women’s Hospital and Harvard Medical School. The answer, based on their research published in a recent issue of the Annals of Internal Medicine, was a surprising yes.
Although heart disease is most commonly associated with high cholesterol, being overweight, inactivity and stress, low levels of vitamin D are also strongly associated with the development of heart disease. It has been hypothesized that cardiovascular disease might be related to sun exposure and, ultimately, vitamin D levels. Several studies have demonstrated that low levels of vitamin D strongly correlated with heart attacks and that these heart attacks were more common in the winter and in higher latitudes, when sun exposure is lower. The incidence of heart disease decreases with altitude, because of increased sun exposure.
Vitamin D is a fat-soluble vitamin and we usually think of it as helping to prevent bone loss. However, research over the past decade has shown that it is important in preventing a number of different cancers, as well as lowering the risk of developing dementia. It also is important for good skin function as well as enhancing immunity. There are several forms of vitamin D and light is required to produce the most active form.
In the current Harvard study, more than 18,000 men, free of heart disease, had their vitamin D levels followed over 10 years. During the 10-year period, 454 men had either a heart attack or fatal coronary event. Other factors involved in heart disease, such as high cholesterol, smoking and diabetes, were taken into consideration. Those with the lowest levels of vitamin D at the beginning and end of the study had the highest risk of heart attack. Those with the highest levels of vitamin D had the lowest risk of heart attack and those with an intermediate level of vitamin D had an intermediate risk of heart attack.
Low vitamin D levels are common in people who live in the northern latitudes – like Chicago. People of color have an increased risk of low vitamin D. In my own experience, about 70 percent of my patients have very low to undetectable levels of vitamin D when I first see them.
Keep in mind that the ultraviolet rays of the sun that produce vitamin D also increase the risk of skin cancer. Although there is no universal consensus on sun exposure, the American Dermatology Association advises avoiding unprotected sun exposure between 10 a.m. and 4 p.m. and getting vitamin D through diet and supplements.
The results of the Harvard study demonstrated that simply increasing dietary vitamin D can significantly reduce the risk of developing heart disease. The recommended daily amount of 400 IU per day is woefully inadequate and most people need a lot more. The best dietary sources of vitamin D are herring and some fish oils. However, most people need to take vitamin D-containing supplements.
Although vitamin D is very safe, there are potential toxicities at very high doses, especially in children. Often, a simple blood test for vitamin D can determine whether you need additional supplementation.
Posted November 19, 2008.
