This is an interesting article, that details the results of an analysis of many scientific studies:
Experts do not know exactly how the plant lifts depression, although most believe it probably works by keeping the chemical serotonin, which is linked to positive moods, in the brain for longer.
The study’s lead author, Dr Klaus Linde, from the Centre for Complementary Medicine in Munich, pooled data from 29 studies involving 5,489 patients with mild to moderately severe depression.
‘Overall, the St John’s Wort extracts tested in the trials were superior to placebo, similarly effective as standard anti-depressants, and had fewer side effects than standard anti-depressants,’ he said.
But he pointed out that St John’s Wort products available in health food shops and chemists differed greatly and some may be more effective than others.
‘Using a St John’s Wort extract might be justified but products on the market vary considerably, so these results only apply to the preparations tested,’ he explained.
The findings were published by the Cochrane Library, which specialises in systematic reviews of research studies…
The studies I have seen on Saint John’s Wort are mixed. Some say it is effective, others say it is not. It seems to be effective for mild depression (exercising and getting fresh air seem to be as well). Either way, it is nice to know there is a safer, cheaper, alternative to prescription anti-depressants (although I would not go off one without working with a doctor!; It is also not wise to self-treat depression).