St. John's wort, the over-the-counter herbal remedy widely touted for combating depression, has failed a major test for effectiveness. Investigators led by a Vanderbilt University researcher studied 200 patients at 11 academic medical centers throughout the United States. All had been diagnosed with major depression--that is, multiple symptoms such as fatigue and loss of interest in formerly pleasurable activities combined with impairment in day-to-day functioning.
For 8 weeks, about half of the participants took St. John's wort extract, while the remainder received look-alike sugar pills. At the conclusion of the study, there were no significant differences in depression between the groups.
These results differ from those of numerous prior studies that have shown benefits for St. John's wort. However, those studies generally contained methodologic flaws that the Vanderbilt study was designed to address. They didn't run for a long enough time, for instance, or had too few subjects.
Of course, a single study is never sufficient by itself to provide definitive answers across the board. It is possible, for example, that the herb may be effective in people who are only mildly depressed. Rigorous research has not shown that, but results from a second major study that should help clarify the issue are expected later this year.