A combination of B vitamins may help lower the risk of a second stroke, as well as reduce the risk of cardiac events and death, according to a report in the journal Stroke.1 The supplement studied contained vitamins B6, B12, and folic acid, which are known to reduce blood levels of homocysteine, a risk factor for cardiovascular disease.
Led by Dr. David J. Spence, scientists from the Stroke Prevention and Atherosclerosis Research Center (Ontario, Canada) conducted an efficacy analysis of data from the Vitamin Intervention for Stroke Prevention (VISP) trial.1 A 2004 report from the VISP study group had reported that combined B vitamin therapy modestly lowered homocysteine levels, but did not reduce the risk of stroke recurrence, cardiac events, or death.2
When Dr. Spence and colleagues re-analyzed the results of the VISP trial, however, a different picture emerged. Noting that the trial included patients who were unlikely to respond to treatment due to existing vitamin B12 deficiency or renal failure, Spence’s group re-examined the results in a subgroup of 2,155 subjects deemed most likely to respond to treatment.1
In this group, combination B vitamin therapy demonstrated benefits in preventing recurrence of stroke and cardiac events.1 Specifically, a higher-dose B vitamin combination (25 mg of B6, 0.4 mg of B12, and 2.5 mg of folic acid) reduced the risk of recurrent stroke, death, and heart disease by 21% compared to a lower-dose B vitamin supplement (0.2 mg of B6, 0.006 mg of B12, and 0.02 mg of folic acid). When the researchers subdivided the patients by baseline levels of B12, thus identifying patients with difficulties absorbing the vitamin, the differences between the high- and low-dose groups further widened. Individuals with baseline B12 levels at or above average who received the higher-dose supplement had the best overall outcomes; those with below-average baseline B12 levels who received the lower-dose supplement had the worst outcomes.1
Dr. Spence noted that while folate fortification of foods is widespread, vitamin B12 status varies widely among patients, and patients’ response to vitamin therapy for lowering homocysteine may largely depend on B12 levels. Higher doses of vitamin B12 or other measures may be necessary to adequately lower homocysteine levels and thus to reduce the risk of stroke, cardiac events, and death.1 Life Extension has long contended that higher doses of B6 (100 to 1000 mg/day) are needed to achieve optimal homocysteine-lowering effects.
—Elizabeth Wagner, ND