The Cochrane Systematic Review supports an earlier research in which it was shown that extracts of the plant Hypericum perforatum, commonly known as St. John's wort, 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," said lead researcher, Klaus Linde of the Center for Complementary Medicine in Munich, Germany.
St. John's wort has 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.
In the study, the researchers assessed 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.
The trials, in which St. John's wort was compared to other remedies, found that not only were the plant extracts considered to be equally effective, but fewer patients dropped out of trials due to adverse effects.
However, the results were found to be more favorable in trials conducted in German speaking countries, where St. John's extracts have a long tradition and are often prescribed by doctors.
Despite the favorable findings for St. John's wort, researchers are still refraining from making generalizations about the plant's use as an anti-depressant.
In fact, they are not even recommending the patients to consult 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," said Linde.