To B or not to B?

High doses of B vitamins didn't lower the risk of heart disease in high-risk patients in two new studies.

Canadian researchers gave more than 5,500 people with heart disease or diabetes either a daily placebo or a combination of folic acid (2,500 mcg), vitamin B-6 (50 mg), and vitamin B-12 (1,000 mcg) as part of the Heart Outcomes Prevention Evaluation (HOPE-2) trial.

After five years, the B-vitamin takers had no lower risk of heart attacks than the placebo takers. But they did have a 24 percent higher risk of being hospitalized for unstable angina and a 25 percent lower risk of stroke. (Unstable angina chest pain that occurs when heart muscle gets too little oxygen--can be a sign of an impending heart attack.)

The Norwegian Vitamin (NORVIT) trial gave more than 3,700 heart attack patients either a placebo, folic acid (800 mcg), vitamin B-6 (40 mg), vitamin B-12 (400 mcg), or some combination of the three B vitamins every day for three years. The results suggested that those who took all three vitamins might have had a higher risk of heart attack, but not cancer, as preliminary results had suggested (see Jan./Feb. 2006, p. 8).

What to do: It's not worth taking high doses of B vitamins to lower your risk of heart disease or stroke. (It still makes sense to take a daily multivitamin with B vitamins, though.) The number of strokes in this study was too small to conclude that B vitamins can lower the risk, especially since they failed to lower the risk of strokes in two other trials.

N Eng. J. Med. 354: 1567, 1578, 1629, 2006.