New research provides support for the use of St. John's wort extracts in treating major depression. A Cochrane Systematic Review backs up previous research that showed the plant extract is effective in treating mild to moderate depressive disorders.

"Overall, we found that the St. John's wort extracts tested in the trials were superior to placebos and as effective as standard antidepressants, with fewer side effects," says lead researcher, Klaus Linde of the Centre for Complementary Medicine in Munich, Germany.

Extracts of the plant Hypericum perforatum, commonly known as St. John's wort, have long been used in folk medicine to treat depression and sleep disorders. The plant produces a number of different substances that may have anti-depressive properties, but the whole extract is considered to be more effective.

Cochrane Researchers reviewed 29 trials which together included 5,489 patients with symptoms of major depression. All trials employed the commonly used Hamilton Rating Scale for Depression to assess the severity of depression. In trials comparing St. John's wort to other remedies, not only were the plant extracts considered to be equally effective, but fewer patients dropped out of trials due to adverse effects. The overall picture is complicated, however, by the fact that the results were more favourable in trials conducted in German speaking countries, where St. John's extracts have a long tradition and are often prescribed by doctors.

Despite the favourable findings for St. John's wort, researchers are anxious not to make generalisations about the plant's use as an anti-depressant and recommend consulting a doctor in the first instance, especially as the extracts can sometimes affect the actions of other beneficial drugs.

"Using a St. Johns wort extract might be justified, but products on the market vary considerably, so these results only apply to the preparations tested," says Linde.