Randomized Trial: B Vitamins
Lowered Risk Of Stroke and Cardiac Events

A combination of B vitamins can help reduce the risk of a second stroke, cardiac events and death, according to study published in the journal Stroke.

The combination of folate, B12 and B6 is already known to lower levels of homocysteine in the blood, a risk factor linked to cardiovascular disease. However, firm evidence that lowering homocysteine levels corresponds with reduced risk for stroke has been awaiting completion of randomized controlled studies.

One of the first studies published was the Vitamin Intervention for Stroke Prevention (VISP) trial. The VISP study group reported that while the B vitamins therapy had lowered homocysteine levels modestly in patients with nondisabling stroke, the combination did not reduce the risk of a recurrent vascular event. However, a second group of doctors re-analyzed the VISP trial data and an entirely different conclusion emerged.

When Dr. David J. Spence and scientists from the Stroke Prevention and Atherosclerosis Research Center in Ontario, Canada conducted their efficacy analysis of the VISP data, it turns out that the trial included patients who were not likely to respond to the vitamin treatment.

Spence and colleagues analyzed the results for a subgroup of subjects that excluded individuals with very low or very high levels of B12 (representing the 25th and 95th percentiles). Among the 2155 patients remaining, there was a 21% reduction of stroke, death or coronary events.

When the researchers subdivided the patients by their initial level of B12, the difference between the treatment groups widened further. Participants who fared the best were those with higher baseline B12 levels who received the high-dose vitamin combination (25 mg of B6, 0.4 mg of B12, and 2.5 mg of folate); those who did the worst came to the trial with lower levels of B12 and received a low dose (0.2 mg of B6, 0.006 mg of B12, and 0.02 mg of folate).

In the era of folate-fortified foods, vitamin B12 status may now be the key variable in lowering homocysteine to safe levels. Higher doses of B12, plus other therapies, may be required to lower homocysteine and thus reduce the risk of stroke, death, and heart attack.

• Additional studies are forthcoming that will further demonstrate whether folate intake has a direct, causal role in reducing the risk for stroke, heart attack, or other cardiac events.
• Intake of more than 1000 mcg/day of folate can hide symptoms of B12 deficiency. A blood test can measure serum B12, or see if methylmalonic acid is elevated as a proxy for functional B12 shortage. Oral supplementation with 1000 mcg/day of B12 corrects or protects against most cases of deficiency (except those due to metabolic or serious malabsorption issues). If untreated, B12 deficiency can result in nerve damage.
• This article is not intended to replace the advice or attention of your doctor or other health care professional. Do not stop taking medications or start taking any nutrition supplement without first speaking to a qualified health care professional.