TUESDAY, April 23, 2002 (HealthDayNews) -- You've probably heard about the heart-healthy powers of vitamins such as A, C and E. Now, researchers say vitamin D could soon join their ranks as a nutrient offering cardiovascular protection, especially for women.
In a new study presented today at the American Heart Association's Asia Pacific Scientific Forum in Hawaii, researchers offered the first piece of evidence that vitamin D may reduce the risk of heart disease in women, particularly those over age 65.
"This is potentially exciting because it may lead to more research. And, if it really works, vitamin D is both inexpensive and safe, which would indeed be great news in an era of exploding health-care costs," says study author Dr. Paul Varosy, a researcher in cardiology and medicine at the University of California at San Francisco and the San Francisco VA Medical Center.
While previous studies have examined links between heart attacks and low blood levels of vitamin D, this is believed to be the first research to look at the overall effects of vitamin D on the cardiovascular system -- particularly the risks of cardiovascular disease in older women.
New York cardiologist Dr. Stephen Siegel finds the study interesting, but inconclusive.
"Vitamin D is critical in calcium metabolism, and both calcium absorption and metabolism are affected by vitamin D. So, one could make an argument that it may affect calcium either going into or coming out of the artery, and in that sense it may ultimately have an effect on heart disease," says Siegel, a clinical professor of medicine at New York University School of Medicine.
"However, what we don't know yet is whether or not that effect is powerful enough to influence the rate of heart disease, and I think it's way too early to tell," he says.
The idea that vitamin D might play a role in heart health grew out of its link to bone health. Vitamin D is key to a process known as calcification, a metabolic action that helps keep enough calcium in bones so they remain healthy and strong.
However, while calcification is a good thing for your skeleton, it may not help your arteries.
Some studies show that women who suffer from the bone-thinning disease osteoporosis are more likely to die of heart disease. So, Varosy theorized the same metabolic activity that caused calcium to be lost from these women's bones may somehow contribute to its buildup in their blood vessels and, ultimately, increase their risk of heart disease.
The entire process, he guessed, could be influenced by levels of vitamin D.
Varosy's study involved 9,704 women ages 65 and older who were originally enrolled in the Study of Osteoporotic Fractures, a National Institutes of Health project designed to look at risk factors and outcomes of osteoporosis.
From this group, he looked at 4,272 women who, at the time of the original study, reported using vitamin D supplements. Although researchers on the original study did not question the women as to the type or amount of vitamin D they were taking, Varosy believes most were taking the standard, daily recommended dose of 400 units, the amount found in most multivitamins.
During the 11 year follow-up study, 420 women died of coronary heart disease. When researchers compared the number of deaths to vitamin use, they found that those women who reported using vitamin D supplements had a 31 percent decreased risk of dying from heart disease than the women who said they took no supplements.
Although Varosy says his study accounted for such factors as smoking, use of calcium supplements, health status and exercise, what could not be immediately verified was the full impact of the vitamin D.
"We don't have data to tell us what proportion of our subjects were taking multivitamins and what proportion were taking vitamin D alone, and this is one of the most important limitations of the study," Varosy says.
Siegel agrees: "You can't be certain from this particular study that vitamin D was the nutrient that made the difference. Or if it did, how much it might take to convey protection."
While Siegel calls the results "interesting and exciting" and sees no real downside to taking vitamin D, he also cautions that, "if this was a drug that showed this kind of effect, we'd require a little bit more in terms of safety and efficacy data before making any blanket recommendations. And I think this should be the case concerning vitamin D and heart disease as well."
Varosy feels the same way: "It is far too early, based on this study alone, to advocate that people start taking vitamin D for the purpose of reduction of heart disease risk. It's potentially an exciting idea, but it's just too soon."
Both Siegel and Varosy agree women should check with their doctor before starting any supplement, particularly if they are at risk for heart disease.
What To Do: Are you are risk for heart disease? To calculate your risk, visit the University of Kansas Medical Center. To learn more about vitamin D and bone health, check Osteoporosis Online.
