Extracts of the plant Hypericum perforatum - known as St. John's Wort - are a traditional herbal remedy to treat mild forms of depressionplugin-autotooltip__plain plugin-autotooltip_bigMajor Depressive Disorder
Major Depressive Disorder (MDD), also known simply as 'depression', is a mental disorder characterized by at least two weeks of pervasive low mood.
Current estimates are that severe depression affects around 2% of the global population at any given time, currently more than 150 million. The majority of cases don't appear to have an obvious personal and/or societal cause..
The extracts are currently available under medical prescription in some countries, notably Germany, where it's an officially approved treatment. In other countries (e.g. the US) the plant is not registered as a medicine, but as a 'food supplement',
The effectiveness of the treatment is still under discussion, but the plant appears to work at least as well as commonly prescribed SSRI drugs (e.g.Fluoxetineplugin-autotooltip__plain plugin-autotooltip_bigFluoxetine
Fluoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI) used in the treatment of Major Depressive Disorderand Obsessive-Compulsive disorder etc.. It's marketed under the trade names Prozac, Sarafem, Fontex and many others.
SSRIs are believed to act by inhibiting the re-uptake of the hormone serotonin) but with lower prevalence of adverse side effects.
The active ingredients are believed to be hypericin and hyperforin - possibly in conjunction with other compounds.
It's currently not known exactly how the plant's extracts help to alleviate depression, but they are thought to play a role in regulating serotonin levels. (For technical details see : CNS Drugs 17(8):539-62 )
Also see : Wikipedia