The review was published in the Cochrane Database of Systematic Reviews 2008. The studies came from various countries, and tested various hypericum extracts, on patients suffering from mild to moderately severe symptoms of depression. The review concluded:

The available evidence suggests that the hypericum extracts tested in the included trials a) are superior to placebo in patients with major depression; b) are similarly effective as standard antidepressants; c) and have fewer side effects than standard antidepressants.

Background

There are 370 species of this aromatic, perennial herb Hypericum perforatum. The herb has golden-yellow flowers and the dried herb consists of the plant's overground parts (leaves and flowering tops).

It has been used as an herbal remedy since the Middle Ages, for its anti-inflammatory, diuretic and wound healing properties, as well as conditions like back pain and anxiety.

It is now widely used for treating patients with depressive syndrome, and is also used for its anti-viral, anti-bacterial, anti-inflammatory and other properties. Since 1995, it has become the most prescribed antidepressant in Germany, where it is a licensed herbal medicine, and is considered safe and effective for the treatment of children.

Studies

The herb has been studied extensively, particularly in Germany. The studies initially focused on hypericin as the active constituent responsible for the herb's anti-depressant effects. Many of these studies have shown that for mild to moderate depression, St John's Wort was an effective treatment.

However in January 2001, the Journal of the American Medical Association (JAMA) published results of a study that compared St John's Wort to a placebo for the treatment of major depression. It concluded that St John's Wort was not effective for the treatment of major depression. Interestingly, this study was funded by Pfizer, the pharmaceutical manufacturer of Zoloft, a leading synthetic antidepressant medication.

Not only was the study said to be flawed because there was no active pharmaceutical drug used to compare with the herb and placebo, but also because the dose of St John's Wort was said to be insufficient.

In 2000, researchers at the University of Frankfurt, extensively studied hyperforin, found instead of the previously thought hypericin, to be the primary active constituent in St John's Wort for treating depression. They stated in their abstract published in Neuropsychopharmacology: that "no other antidepressant compound exhibits a similar broad uptake inhibiting profile", meaning that St John's Wort is more effective than many antidepressants.

A study published in the Wien Med Wochenschr in 2007 explained that several groups of active compounds contribute to the antidepressant effect of the plant extract, and that the herb as a whole should be considered for increased efficacy, not just specific extracts.

Interactions / adverse effects

Adverse effects of St John's Wort are mimimal, and have been found comparable to placebo. A review in 2004 compared adverse events during clinical trials with the herb to those observed under placebo and synthetic antidepressants, and found no specific effects of Hypericum extract.

Howver, caution should be exercised when taking any drug at the same time as St John;s Wort. The herb should also be avoided during pregnancy and lactation. While the side effects are generally minimal, it is essential to seek medical advice if you have a preexisting medical condition or if you are already taking an antidepressant.

References

• Linde K, Berner MM, Kriston L. St John's wort for major depression. Cochrane Database of Systematic Reviews 2008, Issue 4. Art. No.: CD000448.

• Shelton RC, et al. Effectiveness of St. John's Wort in major depression: a randomized controlled trial. JAMA 2001 Apr 18;285(15):1978-86

• Wonnemann M, Singer A, Muller WE. Inhibition of Synaptosomal Uptake of H-L-glutamate and H-GABA by Hyperforin, a Major Constituent of St Johns Wort: The Role of Amiloride Sensitive Sodium Conductive Pathways. Neuropsychopharmacology 2000, 23 188-197.

• Butterweck V, Schmidt M. St Johns wort: role of active compounds for its mechanism of action and efficacy. Wien Med Wochenschr 2007;157(13-14):356-61

• Butterweck et al. Solubilized hypericin and pseudohypericin perforatum exert antidepressant activity in the forced swimming test. Planta Med 64(4):291-4. May 1998

• Trautmann-Sponsel RD, Dienel A. Safety of Hypericum extract in mildly to moderately depressed outpatients: a review based on data from three randomized, placebo-controlled trials. J Affect Disord. 2004 Oct 15;82(2):303-7

• Finfgeld DL. Serotonin syndrome and the use of SSRIs. J Psychosoc Nurs Ment Health Serv. 2004 Feb;42(2):16-20