B vitamins are safe, but they don't appear to protect those who have suffered a stroke from heart attacks or new strokes, a large study shows for the first time.
The overall risk of suffering one of these events - between 15 and 17 percent - was similar for patients taking vitamins and placebo pills, respectively.
Until bigger studies have been done, lead author Dr. Graeme Hankey, of the University of Western Australia in Perth, suggested that stroke patients try to reduce their risk through a healthier lifestyle. If necessary, he added, medications such as aspirin and cholesterol-lowering drugs may help.
The new findings, published in The Lancet Neurology, come in the wake of a study showing B vitamins don't protect people who've had heart attacks either.
Since the early 1990s, the hope had been that vitamins - specifically, folic acid and vitamins B6 and B12 - would be a cheap and safe way to protect the ticker.
Amino acid homocysteine
Studies had shown blood levels of the amino acid homocysteine were high in people with heart disease. Researchers speculated that lowering homocysteine levels with B vitamins might in turn safeguard the heart and decrease the risk of strokes.
To test that, Hankey and colleagues followed more than 8,000 stroke patients for about 3 and a half years, on average. The researchers randomly assigned patients to take either inactive placebo pills or vitamins.
There were no differences in side effects between the two groups. In the placebo group, 114 (3 percent) died from heart attack, compared to 118 (3 percent) in the vitamin group. For stroke, the numbers were 388 (10 percent) and 360 (9 percent), respectively.
In a study of this size, Hankey said in an e-mail to Reuters Health, it couldn't be ruled out that even that slight difference was due to nothing but chance.
'Huge global problem'
Neurologist Dr Peter Sandercock of the Western General Hospital in Edinburgh, UK, said it was clear B vitamins didn't help people who'd suffered heart attacks.
And for healthy people, he told Reuters Health, "supplementing your diet by swallowing vitamins is probably never going to be worthwhile".
But in an editorial, he called for larger studies of strokes, which he said affect as many as 15 million people worldwide every year.
"The problem is that stroke is a huge global problem," said Sandercock, who wasn't involved in the new research. Even if the protective effect of B vitamins is small, "you don't want to close the door to something as cheap and simple as vitamin treatment."
He said it was going to be difficult to find sponsors to fund studies of a sufficient size - between 20 000 and 30 000 patients. - (Frederik Joelving, Reuters Health, August 2010)