Two new studies question the conventional wisdom that folic acid and B vitamin supplementation lowers cardiovascular risk. The logic behind supplementation has been that it reduces blood levels of a protein called homocysteine, long linked to heart attack and stroke. But the new research suggests that lowering homocysteine this way has no effect on preventing heart attacks - and may even trigger a slight rise in heart attack risk. There was one glimmer of hope for people taking these supplements, however: One of the two studies did note a "marginally significant" decrease in stroke risk after supplementation. Over the three years of the trial, the researchers found that while homocysteine levels dropped an average of 27 percent among people taking folic acid and vitamin B12, this decline in the blood protein had no significant effect on whether people had another heart attack or died from another heart attack. In fact, people taking all three supplements actually experienced a slightly increased risk of having another heart attack, the researchers found. Overall, however, the researchers concluded that "combined daily administration of 2.5 mg [milligrams] of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12 for five years had no beneficial effects on major vascular events in a high-risk population with vascular disease." They added that "our results do not support the use of folic acid and B vitamin supplements as a preventive treatment."