The popular herbal remedy St. John's wort is not effective in treating major depression, according to results of a clinical trial reported in the 18 April issue of the Journal of the American Medical Association. But experts are divided about whether the trial, which was funded and partly designed by Pfizer, the pharmaceutical company that sells the popular prescription antidepressant Zoloft, really proves that the herb does not work.
St. John's wort, Hypericum perforatum, is a small flowering weed that has been used for centuries to treat what were known as "nervous conditions." Extracts of the herb are sold widely today. More than 30 studies have claimed that the remedy eases depression. But these studies had "substantial limitations," says psychiatrist Richard Shelton of Vanderbilt University in Nashville, Tennessee, such as small sample sizes or unreliable methods for rating depression.
To test St. John's wort more stringently, Shelton and colleagues at 10 other medical centers tested the extract and a similar-tasting placebo pill on 200 people suffering from depression. The subjects' symptoms were severe enough to interfere with day-to-day functioning but not severe enough to make them suicidal. The researchers followed the subjects' progress using a standardized rating scale that gauges symptoms such as fatigue, sleep problems, and depressed mood. After 8 weeks, depression eased at about the same rates in patients taking St. John's wort and placebo. What's more, the results were the same when patients, rather than researchers, rated their own depression. "Until we have good data to support St. John's wort, we probably shouldn't be recommending it," Shelton says.
Not so fast, say other experts. Unlike in many clinical trials, the researchers did not test a third group of patients with a drug that's known to work--a procedure that ensures that true antidepressive effects could be detected, says psychiatrist Fred Quitkin of Columbia University College of Physicians and Surgeons in New York City. Moreover, the herb may still ease mild depression, says internist Barak Gaster of the University of Washington, Seattle. Still, although the results are not conclusive, they "have to be taken seriously," says Quitkin, and "another good study would be the kiss of death for St. John's wort."