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The German findings are collected in a 685-page tome called The Complete German Commission E Monographs, which the American Botanical Council in Austin, Texas, recently published in English. It tells which herbs have proved safe and beneficial but warns against side effects and other risks. It advises pregnant and nursing women not to take kava, for example, and notes that some people may become sensitive to sunlight when using St. John's wort. It approves standardized doses of ginkgo extract but rejects nonstandard preparations made from whole leaves as untested and potentially hazardous. At the same time, it turns thumbs down on folk remedies like nutmeg for upset stomachs, noting scant evidence that it works and warning that large doses can cause hallucinations.
Similarly, last week the Archives of Family Medicine, a sister publication of J.A.M.A., reported a study suggesting that echinacea was no better at preventing colds than a placebo (a pill with no active ingredients). But the researchers conceded that their sample size, 302 volunteers, may have been too small to detect modest differences and concluded that more study was needed. The researchers didn't test whether echinacea alleviates colds already in progress.
In considering the effectiveness of any medicine, conventional or herbal, it's important to consider that the placebo effect, or the patient's desire to believe in a cure, can have a powerful influence. Recent studies show, for instance, that while 86% of men taking a baldness remedy reported that it worked, so did 42% of men taking a placebo.
The history of diet supplements is rife with fads that fizzled or proved dangerous to health. Melatonin, a hormone used to prevent insomnia, became a craze a few years ago, when, on the basis of studies with mice and rats, some researchers hailed it as a miracle cure for aging. But when later reports cast doubt on the findings, sales of melatonin went back to sleep. Last year a tea made from the Chinese kombucha mushroom that was promoted as a remedy for cancer caused four people to be hospitalized for conditions ranging from jaundice to headaches and nausea.
Research on many herbs is generally at the stage where studies of vitamins and minerals were a decade ago. Vitamins, though, are easier to investigate because the active ingredients in plant remedies can take years to identify. Vitamin C has been shown to protect against infection and bruises, while vitamin E improves circulation and helps lower blood pressure. But megadoses of many nutrients can have dangerous side effects. Overuse of vitamin D, a substance that promotes the growth of bone and teeth in children, can be particularly toxic, as can overuse of the mineral iron by older adults.
Research on herbs has lagged in the U.S. because companies have little incentive to spend $500 million on 10 to 15 years of tests--as pharmaceutical firms typically do to check out new medications. Unlike drugs, most herbal preparations cannot be patented, so the testing company would not be rewarded for its efforts. The FDA, meanwhile, would have to prove that a supplement is unsafe before yanking it off the market, yet it has no authority to test nutritional supplements. "The result is that there are a lot of products on the market that little is known about," says FDA deputy commissioner for policy William Schultz.