Megadoses of Vitamin B May Be Bad for Heart
Folic Acid, B-6 Combo Raises Chance of 2nd Heart Attack
WebMD News Archive
Sept. 6, 2005 (Stockholm, Sweden) -- When it come to heart health, megadoses of vitamin B may do more harm than good.
Contrary to their expectations, Norwegian researchers found that giving high doses of B vitamins to heart attack survivors does not lower the risk of a second heart attack or stroke. And survivors who took megadoses of two B vitamins -- B-6 and folic acid -- upped their risk of future heart disease complications.
While the researchers only looked at people who already had a heart attack, the findings likely apply to healthy people trying to ward off heart disease as well, says researcher Kaare Harald Bonaa, MD, professor of cardiology at the University of Tromso, Norway.
The Homocysteine-Vitamin B Debate
No one knows how many people take the vitamins for heart protection, but experts suspect the number is high. The reason: An increased risk of heart disease and stroke has been associated with elevated blood levels of a protein called homocysteine. In healthy people vitamin B helps lower homocysteine levels.
But there is debate about what role, if any, homocysteine has in the development and prevention of heart disease.
The new findings were presented at the annual meeting of the European Society of Cardiology.
Those on Multiple Vitamins Fare Worse
The study included nearly 4,000 heart attack survivors who were followed for an average of 3.5 years.
They took either high-dose (40 milligrams) vitamin B-6 capsules, high-dose (0.8 milligrams) folic acid capsules, both high-dose folic acid and high-dose vitamin B-6, or placebo daily in addition to their standard heart medications.
There was no difference in the number of new strokes and heart attacks among people taking vitamin B-6 alone, folic acid alone, or placebo.
But people taking both vitamins were 20% more likely suffer a heart attack or stroke than the others.
People who had kidney problems or took multiple vitamin supplements fared the worst, Bonaa says.
"The homocysteine hypothesis is dead. Homocysteine is not a risk factor for heart disease. It is an innocent bystander," he tells WebMD.
But American Heart Association spokesman Timothy Gardner, MD, a heart surgeon at the University of Pennsylvania in Philadelphia, says there's a long way to go before that conclusion can be drawn.
"What has been demonstrated by this trial is that vitamin B-6 and folic acid are not helpful in preventing heart disease. The key message for people taking vitamins is to be careful -- you can overdo what you thought was beneficial," Gardner tells WebMD.
"In recommended amounts, these vitamins may not be harmful," he tells WebMD. "That's a question for future research."