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B vitamins may prevent strokes

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B vitamins may prevent strokes By Ben Wasserman Nov 15, 2005, 01:01

Email this article Printer friendly page Taking high doses of B vitamins including folic acid, B6 and B12 may help reduce the risk of a second stroke and heart attacks, according to a new study titled "Vitamin Intervention for Stroke Prevention Trial - An Efficacy Analysis," published in the Nov. 1 issue of Stroke.

Canadian researchers J. David Spence, MD, FRCPC, FAHA and colleagues from the Stroke Prevention and Atherosclerosis Centre and other organizations found that "for the combined end point of ischemic stroke, coronary disease, or death, there was a 21% reduction in the risk of events in the high-dose group compared with the low-dose group."

The new findings were contradictory to previous studies. One study conducted by researchers at the University of Tromsø, Norway found treating patients who had a heart attack with high doses of B vitamins did not lower the risk of getting another heart attack or stroke, although homocysteine levels, which have been associated with an elevated risk of heart disease, were lowered after the treatment.

Even worse, harmful effects were observed among those patients with high levels of homocysteine at the start of the trial, or with impaired renal function, or with other vitamin supplements being taken in addition to the study medication. The study was presented at the Norwegian Vitamin Trial at the European Society of Cardiology Congress in Stockholm on Sept. 5, 2005

The findings of the current study were also contradictory to a previous study of the same authors who wrote, "treatment with a combination of folic acid, pyridoxine (vitamin B6) and cobalamin (vitamin B12) reduces plasma H(e) levels in most cases, restores endothelial function, and regresses carotid plaque, but there is no evidence that such treatment will reduce clinical events." The study titled Vitamin Intervention for Stroke Prevention (VISP) trial: rationale and design was published in the Feb. issue of Neuroepidemiology.

Dr. Spence and colleagues wrote in their current report that "reasons for lack of efficacy may have included folate fortification of grain products, inclusion of the recommended daily intake for B12 in the low-dose arm, treatment with parenteral B12 in patients with low B12 levels in both study arms, a dose of B12 too low for patients with malabsorption, supplementation with nonstudy vitamins, and failure of patients with significant renal impairment to respond to vitamin therapy."

In the current study of 2155 patients, the authors excluded those with low and high B12 levels at baseline (637 pmol/L, representing the 25th and 95th percentiles), as they were likely to have B12 malabsorption or to be taking B12 supplements outside the study or to have significant renal impairment (glomerular filtration rate <46