Vitamin B May Not Guard Against Second Stroke, Heart Attack

Stroke patients who take vitamin B supplements to lower their homocysteine levels may not be protected from second strokes or heart attacks, a new study finds. The report is published online in The Lancet Neurology.

Earlier studies found an association between homocysteine in the blood, and an increased risk for stroke and heart attack. Vitamin B supplements lower homocysteine levels, but whether this really has an effect on stroke and heart attack risk has been unclear, the Australian researchers note.

"B vitamins are safe, but they were not, statistically, significantly more effective than placebo in preventing major vascular events among stroke and TIA [transient ischemic attack] patients," says lead researcher Graeme J. Hankey, MD, head of the stroke unit at Royal Perth Hospital in Western Australia. "B vitamins have not been proven to have a role in secondary stroke prevention."

For the study, Hankey and his colleagues in the Vitamins to Prevent Stroke (VITATOPS) trial tested whether lowering homocysteine with a combination of folic acid, vitamin B6, and vitamin B12 would lower the risk of a second stroke or heart attack in patients who had a recent stroke or transient ischemic attack.

In the trial, 8,164 patients were randomly assigned to daily doses of either B vitamins or a placebo in addition to standard care.

Over 3.4 years of follow-up, the researchers found the vitamins were no more effective than placebo. In all, 15% of the people taking B vitamins had a second stroke or heart attack or died, compared with 17% of those receiving placebo. B vitamins did, however, lower homocysteine levels.

People taking the vitamins had no adverse reactions and the vitamins were well-tolerated, the researchers note.

Despite these findings, Hankey isn't sure that B vitamins don't work. "Our study may well have been underpowered statistically," he says.

Had the trial gone on longer, a "significant treatment effect may have emerged, and has thus been missed in our study," Hankey adds.

Source: Brigham and Women's Hospital