THURSDAY, Feb. 19, 2009 (HealthDay News) -- People with heart disease who take high doses of B vitamins are somewhat less likely to suffer from stroke, especially if they're under 70, a new Canadian study suggests.
But other studies have come to opposite conclusions about whether vitamins really protect against cerebrovascular disease, noted Dr. Larry B. Goldstein, director of the Duke Stroke Center at Duke University, in Durham, N.C.
"We will need to carefully review this study in light of these other reports," said Goldstein. "There remains no evidence that general vitamin supplementation lowers risk of stroke or other cardiovascular events, and considerable evidence that it is ineffectual."
The Canadian researchers sought to determine whether high doses of three B vitamins could dampen the risk of stroke by lowering levels of an amino acid known as homocysteine.
Some research has linked high levels of the amino acid in the blood to a higher risk of stroke, although there's a debate over what this means.
The American Heart Association has made a point of not declaring high homocysteine levels to be a risk factor for heart disease or stroke. In fact, the association doesn't recommend the widespread use of B vitamin supplements to counteract any risk.
In the new study, researchers from the University of Toronto and McMaster University examined the results of a research trial that randomly assigned 5,522 adults with heart disease to either take a daily regimen of several vitamins or placebo pills for five years.
The vitamin regimen included a daily dose of 2.5 milligrams of folic acid (a type of B vitamin), 50 milligrams of vitamin B6 and 1 milligram of vitamin B12. These levels are higher than people would normally get from their diets or from multivitamins, said Lona Sandon, spokeswoman for the American Dietetic Association.
The findings were reported Thursday at the American Stroke Association's International Stroke Conference in San Diego.
Nearly 5 percent of the participants in the trial suffered from stroke during an average of five years of follow-up. The risk was lower in patients who followed the vitamin regimen, although the researchers described the difference as "modest."
The study's statistics suggest the vitamin therapy would help 13 out of 1,000 subjects avoid a stroke.
Several groups gained more benefit from the vitamin treatment: people younger than 70, those who had higher cholesterol and homocysteine levels at the start of the study, those from areas without folic acid fortification in food, and those who weren't receiving antiplatelet drugs (such as Plavix) or cholesterol-lowering statins at the start of the study.
The vitamin therapy didn't appear to have an effect on the severity of stroke that some of the participants suffered.
Another study presented at the same meeting found that taking recommended doses of B vitamins reduced homocysteine levels and lowered the chances of another stroke in stroke patients.
The University of California, Los Angeles, researchers collected demographic, clinical and laboratory data on more than 3,000 stroke patients at the start of the study and in follow-up visits of six, 12 and 24 months.
The vitamin group was less likely to have a recurrent stroke by the end of the two-year study (13.4 percent vs. 20.3 percent), the team found
Vitamins aside, experts said a healthy diet is the best way to guard against stroke.
"The best anti-stroke diet is high in vegetables and fruits, including high-fiber produce, low in saturated and trans fat, and higher in plant-based unsaturated fats [such as olive oil, unsalted nuts and avocado], with enough calcium, potassium and omega-3 fatty acids and at a calorie level that helps maintain a healthy weight," said Cynthia Sass, a registered dietitian in New York City.
And don't assume that you can reduce stroke risk by adding supplements to your diet for a few weeks, Sandon added.
"The benefits of vitamins and minerals are not a quick fix like prescription drugs," she said. "Vitamins and minerals must be taken in over several years to glean the benefits."
More information
Learn more about homocysteine from the American Heart Association.
