Scientist Scrutinize Herbal Supplementation Tests

A central criticism of the herbal supplement industry is that many herbal remedies marketed in the U.S. have not yet been thoroughly studied by medical experts. Manufacturers often rely on a small number of preliminary studies and testimonials from people who say the product has worked for them to bolster the claims made in advertisements and on product labels. Medical experts criticize those methods as bad science, and argue that supplement makers' unsubstantiated claims may lure consumers to take products that do not help them and could even cause them harm.

The most sound and highly regarded medical studies are those that subject new treatments to clinical trials, experiments that compare the health outcomes of people who receive the studied treatment, called the experimental group, with the outcomes of people who do not, called the control group. Successful clinical trials must show that the group that received the treatment had better results than the group that did not.

The effects of any given medication or treatment may be confounded by what is known as the placebo effect. The placebo effect refers to medical benefits that patients gain from chemically inactive substances. In a clinical trial for a drug, for example, subjects do not know whether they are taking the experimental remedy or a similar-looking, yet inert, pill. Many people in the control group may actually experience or report physical improvement simply because they believe they are receiving a beneficial medication. Physicians note that in trials of new drugs, as many as 30% to 40% of people in the control group may report improvement, even though they have been given nothing more than a sugar pill.

Experts say that if a supplement is safe, the placebo effect can be beneficial for many people, whether or not the product itself is effective. However, if the safety of a product is unknown, its dangers could outweigh the benefits of the placebo effect.

Critics of herbal supplements say that because of the placebo effect, anecdotal evidence and testimonials, on which some supplement makers rely to support their claims, are dangerous sources of medical advice. Since a certain number of people who receive any treatment are expected to benefit from the placebo effect, medical benefits cannot automatically be attributed to the treatment itself. Moreover, anecdotal evidence that a particular supplement is effective does not take into account potential side effects and damage that the supplement could also cause.

Adding to the confusion over the testing of herbal products are herbal supplement manufacturers, who often make broad, largely unsubstantiated claims in promoting their products. The studies that bolster a supplement's claims are often exaggerated on labels and in advertisements. For example, preliminary studies of an extract of ginkgo biloba leaves have shown that in some people with Alzheimer's disease, it may help relieve mild dementia, a condition that impairs mental functioning. Ginkgo has since been marketed as a general memory aid, although there is no sold evidence that the product has an effect on healthy people's functioning.

Moreover, supplement manufacturers often make claims about their products that are unrelated to the effects that have been tested. The hormone melatonin, for example, has been shown by some studies to relieve jet lag. It is often promoted, however, as a supplement to slow the aging process, although those claims have not been supported by thorough scientific testing.

Advocates of herbal supplements argue that mainstream medical practitioners are needlessly hostile to remedies that may benefit the people who take them. They point out that approximately 75 years ago, the American Medical Association, the nation's most influential doctors' organization, called the burgeoning vitamin industry a "gigantic fraud," yet today vitamins are generally accepted by the medical profession, and many doctors recommend them to their patients. Proponents of herbal remedies believe that those products, too, will someday be more widely accepted, despite the fact that they are criticized as unproven today.

Supplement manufacturers say that expecting herbal supplements to undergo the same clinical trials as synthetic drugs is unreasonable. Such trials cost millions of dollars, they point out, and that money would be difficult to earn back, even if the trial resulted in bringing a new product to market. That is because medicinal plants cannot be patented by a single company, as synthetic drugs can. So while one herbal supplement manufacturer may spend money to test a product, others might spend no money and still reap the profits that result from a successful trial.

The federal government has taken steps to promote research on what it considers to be understudied herbal remedies. In 1991, Congress created an Office of Alternative Medicine (OAM) within the National Institutes of Health (NIH) to evaluate the effectiveness of a number of alternative medical treatments, including dietary supplements. The OAM, which opened in 1992, conducts research on various alternative treatments and provides funding to outside researchers for similar projects. The OAM's first request for research proposals brought in more than 800 letters, the largest response to a single request for proposals in NIH history. By 1997, funding for the OAM had risen to $12 million, up from $2 million in 1992.

Federal funding for research on herbal supplements has encouraged medical experts to examine the effectiveness and safety of those products. Research on those treatments has increased greatly in the U.S. in recent years, and many experts are also reviewing the body of research on the products from Europe.

Sources

Cowley, Geoffrey. "Herbal Warning." Newsweek (May 6, 1996): 60.

Daniels, Anthony. "To Heal the Hollow Soul." National Review (July 6, 1998): 46.

Hellmich, Nanci. "Many Doubt Supplements Can Live up to the Claims." USA Today (November 25, 1997): 1A.

Krantz, Michael. "The Self-Medication Generation." Time (May 12, 1997): 72.

Okie, Susan. "With Dietary Supplements, Health Claims Needn't Wait for Science." Washington Post (November 25, 1997): A1.