Extracts of St John's wort (hypericum perforatum), a common garden plant with a profusion of yellow flowers, have been used in folk medicine for hundreds of years to treat a range of illnesses.
In some European countries, particularly Germany, it is widely accepted as an effective treatment for psychological problems. In 1994, German doctors prescribed 66 million daily doses of the herbal remedy, known also as hypericum, worth about pounds 26m.
Now scientists from Germany and the United States, have analysed the results of 23 clinical trials involving 1,757 patients with mild or moderate depression who were treated with St John's wort extracts, or a combination of this and other plant extracts, or a placebo, or another drug treatment.
Professor Cynthia Mulrow and colleagues at the San Antonio Cochrane Center, in Texas, and a team led by Dieter Melchart at the Ludwig-Maximilians- Universitat in Munich, found that St John's wort was "significantly superior" to a placebo, and equally effective as standard anti-depressants.
According to the report in tomorrow's issue of the British Medical Journal, there were less than 1 per cent drop outs for side-effects with St John's wort, and 3 per cent with standard anti-depressant drugs. Side-effects occurred in less than 20 per cent of St John's wort patients, and 53 per cent of those on standard anti-depressants.
The team concluded that St John's wort was a promising treatment for depressive disorders, while emphasising that further research was needed to evaluate its safety. "We believe there is good evidence that hypericum is better than placebo in treating some depressive disorders," the doctors wrote. "We do not yet know if hypericum is better in treating certain depressive disorders than others, and neither do we know if different preparations of hypericum are equally effective or the optimum dosages."
In an accompanying BMJ editorial, Peter De Smet, a clinical pharmacologist at the Royal Dutch Association for the Advancement of Pharmacy, said that despite evidence that the plant extract was safe and well-tolerated - there has not been a single report about a serious drug interaction or toxicity in Germany after extensive use - caution was necessary. Extra studies to determine if St John's wort was of use in severe depression were also needed.
St John's wort contains at least 10 substances that may contribute to its effectiveness as an anti-depressant, including hypericum - thought to inhibit an important enzyme in the brain, which has an affect on neurotransmitters which relay messages between brain cells. The remedy is licensed in Germany for the treatment of anxiety, depression and sleep disorders.
There are about 400 species of St John's wort found throughout the world, and it grows well except in extremes of temperature.Reuse content