Study Shows Vitamin B May Lower Stroke Risk

Vitamin B may reduce the risk of stroke in some people, say the Oregon researchers whose study is published today in the journal Stroke.

But Los Angeles stroke experts, while noting that the study has merit, say it is too soon to conclude that Vitamin B therapy is effective for reducing the risk of stroke, which afflicts a half million Americans a year. (A stroke is an interruption in the blood supply to the brain; nearly 150,000 victims die annually.)

Vitamin B may reduce stroke risk, the Oregon researchers say, by breaking down abnormally high levels of an amino acid called homocysteine. (Amino acids are the “building blocks” of proteins.)

In their study, Dr. M. Rene Malinow, professor of medicine at Oregon Health Sciences University, Portland, and his colleagues found high levels of homocysteine in one-third of 99 patients who had suffered strokes, transient ischemic attacks (a stroke “warning”), or who were at high stroke risk because of high blood pressure, diabetes, smoking or hardening of the arteries. The homocysteine levels in these 33 patients were 1.5 times higher than levels in 31 healthy control subjects.

Exactly how this elevated homocysteine may increase stroke risk isn’t known, according to Malinow, who said four or five other studies have suggested the same association between elevated homocysteine and increased stroke risk. One possibility: “The elevated levels of homocysteine may injure the endothelial cells lining the blood vessels,” said Malinow.

Malinow believes the blood test to measure homocysteine, now available only at a handful of U.S. facilities, should be more widely available. Until then, Malinow says, consumers at high risk of stroke might consider requesting this test. If their homocysteine levels are elevated, and pernicious anemia (caused by a Vitamin B-12 deficiency) has been ruled out, taking Vitamin B may be wise. He recommends two milligrams a day of folic acid, which is a member of the B vitamin family.

“One or two milligrams of folic acid a day probably won’t hurt, providing there is no pernicious anemia (the symptoms of which may be masked by taking folic acid),” said Dr. Richard Wright, senior staff cardiologist at St. John’s Hospital and Health Center, Santa Monica, emphasizing that the concept needs further study. “We need more study about the effects of folic acid therapy not just on amino acid levels, but on stroke prevention,” he said.

Dr. Mark Fisher, USC associate professor of neurology, agreed: “I don’t believe that increased levels of homocysteine represent a proven independent risk factor for stroke. It’s a good study, but bears further investigation.”

Until more evidence is gathered, consumers can concentrate on tried-and-true stroke prevention measures, Wright said. “Keep blood pressure under control,” he said. “Don’t smoke, eat a nutritious diet and exercise.”