Feb. 10, 2000 (Washington) -- One day it may be proven that taking vitamins reduces the risk of heart disease, but today is not that day -- despite a Dutch study that showed a 60% reduction in abnormal heart stress tests in people who took vitamin B6 and folic acid for two years, compared to a group who took a placebo. That study, published in Feb. 12 issue of the journal The Lancet, is too small to be conclusive and used measurements of heart health that are fraught with inaccurate results, experts tell WebMD.
Some researchers have come to suspect that high levels of a naturally occurring protein, homocysteine, put people at increased risk for heart problems. The tantalizing, but yet unproven, theory is that the use of simple B vitamins, specifically B6 and folic acid, can reduce these homocysteine concentrations and thwart heart problems. Studies are underway that look at whether these supplements result in reduced numbers of heart attacks, strokes, and other related problems.
The Lancet study also tries to prove this theory, but the Dutch researchers looked at how well their study participants did on exercise stress tests, which are notoriously inaccurate.
"I think this tells us nothing and I am afraid people will misinterpret it," Andrew G. Bostom, MD, tells WebMD. Bostom, an assistant professor at Brown University in Providence, R.I., wrote an editorial critical of the study that also appears in the publication. "They can stand on their heads and spit nickels in the Netherlands about the editorial. But this study still means nothing. It is not a valid design and three of the four things they studied showed no result," he says.
A co-author of the study, however, defended it as an "important first step." Says Coen Stehouwer, MD, "This is the first investigation that has provided some ... proof of the concept. This is only the first step. We clearly do not want to claim that this is all settled, but it is an important step. It is encouraging," though more conclusive proof will come from large studies, he says. Stehouwer is an assistant professor of internal medicine at University Hospital Vrije Universiteit in Amsterdam.
The study began in 1993 with nearly 750 patients who had some evidence of heart disease that occurred before they were 56 years old. The researchers then sought out the siblings of these individuals, and screened them for high levels of homocysteine. A total of 450 siblings were screened for this protein, but the final study sample was much smaller -- 80 joined the placebo group and 78 were placed in the treatment group. The treatment group received 250 mg of vitamin B6 and 5 mg of folic acid daily for two years.
At the end of the two years, those in the treatment group were 60% less likely than those in the placebo group to have abnormal tests during stressful exercise. There was no change in other tests that measure heart function.
In his editorial, Bostom said the study size was too small to be significant and called the use of stress exercise tests questionable. Bostom says studies underway in the U.S. and Europe will indicate whether lowering homocysteine levels with B vitamins actually results in fewer heart problems. Until then, he advises "watching and waiting" and does not recommend that people take higher than recommended doses of B6 and folic acid.
Stehouwer, in contrast, says he sees little peril in suggesting that people who are at increased risk of heart disease consume B6 and folic acid, a practice he says his hospital has adopted. If results from future studies indicate little value, the vitamins can easily be stopped, he says. "What we used were a bit higher than what it the common dose. We believe the chances of doing harm are fairly remote."
But another researcher currently studying this issue feels there is some danger from this study. Charles Hennekens, MD, tells WebMD he fears such studies will prompt people to abandon the more difficult -- but proven -- lifestyle changes they should be making to reduce their risk of heart disease.
"It is premature to begin to tell people to take folic acid [and vitamin B6] to prevent heart disease, but we can't sweep suggestions that high levels of homocysteine are correlated to heart disease," says Hennekens, a visiting professor in the department of epidemiology and public health at the University of Miami. "But these are research questions, not public policy questions. We have a population in the U.S. that prefers prescription of drugs, rather than proscription of lifestyle modifications. If people, hearing the news, relax their efforts at reducing cigarette smoking, reducing obesity, reducing physical inactivity ... that could do damage."
- Doctors in the U.S. say it's too soon to be sure whether vitamins can reduce heart disease risk.
- Observers note that although a Dutch study found some optimistic results, the researchers used testing methods that can be inaccurate.
- Others note that the study was too small to be able to produce results with certainty. The study's co-author, however, says the work is an important first step to understanding the relationship between vitamins and heart disease.