Tuesday, September 06, 2005
Folic acid and vitamin B pills do not ward off heart attacks or strokes and may even be harmful when combined, new research suggests.
Studies showing that the vitamins lower levels of a substance in the blood suspected of playing a role in the development of heart disease have prompted hundreds of thousands of heart patients in the developed world to take them.
However, the first large study of the question, presented Monday at a meeting of the European Society of Cardiology, found that although the supplements dramatically lowered the levels of homocysteine, they offered no heart protection.
It's impossible to analyze the details because it was presented at a conference, not published in a journal, but here's the report:
In the latest study, led by Dr. Kaare Harald Bonaa, a professor of cardiology at the University of Tromso in Norway, 4,749 heart attack survivors were divided into four groups. In addition to standard heart medicines, one group took high-dose vitamin B pills every day for three years. Another took high-dose folic acid. A third group took both pills every day and the fourth group took fake pills.
There was no difference in the groups taking fake pills, vitamin B or folic acid when it came to new heart attacks or strokes. However, there were 20 percent more heart attacks and strokes among the group that took both pills.
Those who fared worst were patients who also had kidney problems, and those who reported they also take other vitamin supplements, the study found.
The recommendation to take folic acid or vitamin B12 grew out of the observation that homocysteine levels were higher in people who had heart disease. Both folic acid and vitamin B12 help lower homocysteine levels. The thinking was that lowering the homocysteine levels would lower heart disease risk, but no cause and effect between homocysteine levels and heart disease was ever observed. It's always been a recommendation that's weak on evidence, but its saving grace was that taking extra B12 or folic acid wouldn't be harmful. This, however, suggests otherwise. So little we know.
UPDATE: From a nurse practitioner in cardiology:
The link mentions vitamin B-6 wheras your summary says vitamin B-12. B-12 would make more sense since if you are deficient in it, then homocysteine levels are elevated.
However this article seems to indicate that B-6 was supplemented, not B-12. Would like to know their hypothesis for using B-6 vs B-12.
The comment about "other supplements" is interesting as well. There was an article in the NEJM a couple of years ago - can't give you the reference right now as I am at home and don't have online access - but it looked at progression of CAD in patients who took simvastatin along with Vit C and E supplements vs simva alone. Those taking the Vit C and E had more progression of dz. I now tell all my patients on statins (since we use mostly simva at the VA) to stop taking Vit C and E supplements and recommend only a multivitamin.
I re-read the story, and it doesn't say which B vitamin the researchers studied. The only reference to B-6 is from a British physician who was not involved in the study saying he wouldn't recommend B-6 vitamins for his patients now. That could be because he went to the conference and knows they studied B-6, or it could be because in Britain, they favor B-6 while here we tend to go for B-12. In the end, it probably doesn't make much difference which B-vitamin your talking about. They're both involved in homocysteine metabolism. And we don't know if homocystiene actually plays a role in causing heart disease or if it's just serves as a marker of something else. (See here.)
UPDATE II: The researchers did use B-6.
posted by Sydney on 9/06/2005 12:58:00 PM 0 comments