My Healthy Heart Articles
Lack of Vitamin D May Increase Heart Disease Risk
03/07/08
Nutrition & Exercise
Eating a well-balanced diet is an essential part of maintaining heart health. New heart disease research now suggests that proper nutrition—specifically getting enough vitamin D—may help prevent heart problems. Vitamin D deficiency is associated with an increased risk of heart disease.
The same vitamin D deficiency that can result in weak bones now has been associated with an increased risk of cardiovascular disease, Framingham Heart Study researchers report in Circulation: Journal of the American Heart Association.
"Vitamin D deficiency is associated with increased cardiovascular risk, above and beyond established cardiovascular risk factors," said Thomas J. Wang, M.D., assistant professor of medicine at Harvard Medical School in Boston. "The higher risk associated with vitamin D deficiency was particularly evident among individuals with high blood pressure."
In a study of 1,739 offspring from Framingham Heart Study participants (average age 59, all Caucasian), researchers found that those with blood levels of vitamin D below 15 nanograms per milliliter (ng/mL) had twice the risk of a cardiovascular event such as a heart attack, heart failure, or stroke in the next five years compared to those with higher levels of vitamin D.
Researchers observed the highest rate of cardiovascular disease events among participants with high blood pressure. After researchers adjusted for conventional cardiovascular risk factors, participants with hypertension and a vitamin D deficiency had about two times the risk of having a cardiovascular disease event in five years.
Cardiovascular risk also increased as vitamin D levels decreased.
Study participants had no prior cardiovascular disease and were tested for vitamin D status and then followed for an average of 5.4 years.
The participants were examined between 1996 and 2001. Researchers obtained medical history, physical examinations and laboratory assessments of vascular risk factors. They also obtained medical records related to cardiovascular disease.
Overall, 28 percent of individuals had levels of vitamin D below15 ng/mL and 9 percent had levels below 10 ng/mL. Although levels above 30 ng/mL are considered optimal for bone metabolism, only 10 percent of the study sample had levels in this range, researchers said.
During follow-up:
- 120 participants developed a first cardiovascular event including fatal and nonfatal coronary heart disease;
- 28 participants had fatal or nonfatal cerebrovascular events such as nonhemorrhagic stroke;
- 19 participants were diagnosed with heart failure; and
- 8 had occurrences of claudication, fatigue in the legs during activity.
"Low levels of vitamin D are highly prevalent in the United States, especially in areas without much sunshine," Wang said. "Twenty to 30 percent of the population in many areas has moderate to severe vitamin D deficiency."
Most of this is attributed to lack of sun exposure, pigmented skin that prevents penetration of the sun’s rays, and inadequate dietary intake of vitamin D enriched foods, researchers said.
"A growing body of evidence suggests that low levels of vitamin D may adversely affect the cardiovascular system," Wang said. "What hasn’t been proven yet is that vitamin D deficiency actually causes increased risk of cardiovascular disease. This would require a large randomized trial to show whether correcting the vitamin D deficiency would result in a reduction in cardiovascular risk."
Therfore, Wang doesn’t recommend physicians check for vitamin D deficiency or that those with a known vitamin D deficiency be treated to prevent heart disease at this time.
During the past decade, researchers have studied several other vitamins that initially showed promise in reducing heart disease. But the vitamins didn’t reduce heart disease in subsequent large randomized trials.
"On the flip side, just because other vitamins haven’t succeeded doesn’t preclude the possibility of finding vitamins that might prevent cardiovascular disease," Wang said. "This is always an area of great interest. Vitamins are easy to administer and in general have few toxic effects."
The American Heart Association recommends that healthy people get adequate nutrients by eating a variety of foods in moderation, rather than by taking supplements. Food sources of vitamin D include milk, salmon, mackerel, sardines, cod liver oil and some fortified cereals. Vitamin or mineral supplements aren’t a substitute for a balanced, nutritious diet that limits excess calories, saturated fat, trans fat, sodium and dietary cholesterol. This dietary approach has been shown to reduce coronary heart disease risk in healthy people and those with coronary disease.
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