Vitamins have little effect in preventing recurrent stroke, according to a report in the February 4 JAMA. James F. Toole, MD, Professor of Neurology and Director of the Stroke Research Center at Wake Forest University Baptist Medical Center in Winston-Salem, and colleagues found nearly identical rates of recurrent strokes and heart attacks between participants on a high dose of folic acid, B6, and B12 vitamins and those taking a low dose. “High-dose vitamin therapy had no effect on stroke prevention, coronary heart disease events, or death in this study, which was disappointing,” Dr. Toole remarked.

The Vitamin Intervention for Stroke Prevention (VISP) study involved 3,680 adults who had already had a nondisabling stroke and were being treated at one of 56 centers in the United States, Canada, and Scotland. Half of the patients were assigned to the high-dose group and half to the low-dose.

During the double-blinded study, 8.1% of patients on the low vitamin dose and 8.4% of patients on the high dose had a second stroke.

The study found that vitamin therapy lowered levels of homocysteine. “Findings in other trials of an association between total homocysteine with increased risk of stroke and heart disease suggest that longer trials in different populations with elevated total homocysteine may be necessary,” the researchers said. In both the low-dose and the high-dose vitamin groups, those with a high homocysteine level at the start of the study were the most likely to have a recurrent stroke.

Of patients in the low-dose, or control, group, 6.7% had a coronary heart disease event, usually a heart attack, compared with 6.3% of patients in the high-dose group. Overall deaths from any cause totaled 5.4% in the high-dose group compared with 6.3% in the low-dose group.

Just after the start of VISP, folate fortification of the US grain supply began (which increased folic acid in breads and other foods containing grains), and it became mandatory in January 1998. This “profoundly reduced” the number of people with low levels of folate and high total homocysteine levels, Dr. Toole said.

The study was stopped in December 2002, when the study’s performance and safety monitoring board told the funding agency, the National Institute of Neurological Disorders and Stroke, that “there was no chance of showing any difference between the two treatment groups during the remaining follow-up period.”

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Suggested Reading
Toole JF, Malinow MR, Chambless LE, et al. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death. The Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. JAMA. 2004;291:565-575.

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