—Studies Conducted in Diseased Population Cannot Be
Applied to General Population or Preventative Benefits of B-Vitamins—
WASHINGTON, D.C., March 12, 2006 – Findings from two new studies (HOPE-2 and NORVIT) on vitamins B-6, B-12 and folate supported the conclusions of a vast body of scientific research which shows that these vitamins help lower homocysteine levels, but failed to support the hypothesis that lowering homocysteine levels in persons who already have cardiovascular disease (CVD) will provide protection against a future cardiovascular event. The studies are being presented at the American College of Cardiology Annual Scientific Session which begins on March 11 in Atlanta, Ga., and will be published in the April 13 issue of the New England Journal of Medicine.
According to Annette Dickinson, Ph.D., consultant and past president of the Council for Responsible Nutrition (CRN), “While these studies contribute importantly to the research base, they have limited application for the general population. These studies did not test whether B vitamins used by healthy people can help keep them healthy. Instead, they looked at whether B vitamins can treat or reverse heart disease in people who already have it. Vitamins should not be expected to perform like drugs—their greatest promise is in prevention.”
CRN pointed out that it is unrealistic to expect a vitamin to undo damage caused by heart disease and that consumers should not be looking for B-vitamins to treat disease. Both these studies involved seriously ill subjects. But what has to be considered, according to Dr. Dickinson, is whether the population studied would have been healthier to begin with if they had been taking B-vitamins and others consistently over time. “That’s the question we’d like to see researched,” she said.
The HOPE-2 study did have some positive findings, including a statistically significant 25% reduction in nonfatal strokes. The authors say this may be due to chance, but similar effects have also been observed in other studies.
At least ten clinical trials are now on-going or have been recently completed looking at whether B vitamins can reduce the risk of CVD. These trials are looking at populations who either already have CVD or are at very high risk of CVD. CRN emphasized that every new study needs to be viewed in context and cautioned against the tendency to look at every trial as conclusive advice for the entire population.
“This is a well-designed and executed trial for the purpose for which it was created. If there is a fundamental flaw,” said Dr. Dickinson, “it is in the reasoning that is the underpinning of many clinical trials on nutrient intervention. There are practical reasons—related to cost, duration and the size of the study group—why these trials are conducted in high risk or diseased populations. But we need to remember that they are not necessarily testing a hypothesis that led us to undertake the trials in the first place. Scientific research does not always provide the yes or no answers that some would like. Our best advice to healthy consumers is not to throw away your vitamins based on the study du jour.”
The Council for Responsible Nutrition (CRN), founded in 1973, is a Washington, D.C.-based trade association representing dietary supplement industry ingredient suppliers and manufacturers. CRN members adhere to a strong code of ethics, comply with dosage limits and manufacture dietary supplements to high quality standards under good manufacturing practices. For more information visit the CRN website http://www.crnusa.org.