St John’s Wort

St John’s wort is the plant species Hypericum perforatum, and is also known as Tipton’s WeedChase-devil, or Klamath weed.

With qualifiers, St John’s wort is used to refer to any species of the genus Hypericum. Therefore, H. perforatum is sometimes called Common St John’s wortto differentiate it. The species of Hypericum are classified in the Hypericaceae family, having previously been classified as Guttiferae or Clusiaceae.[1][2]Approximately 370 species of the genus Hypericum exist worldwide with a native geographical distribution including temperate and subtropical regions of North AmericaEuropeTurkeyRussiaIndia, and China.

St John’s wort is widely known as a herbal treatment for depression

Medical uses

Depression treatment use

St John’s wort is widely known as a herbal treatment for depression. In some countries, such as Germany, it is commonly prescribed for mild depression, especially in children and adolescents.[5]

A report from the Cochrane Review states,

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; and c) have fewer side effects than standard antidepressants.
There are two issues which complicate the interpretation of our findings:
1) While the influence of precision on study results in placebo-controlled trials is less pronounced in this updated version of our review compared to the previous version (Linde 2005a), results from more precise trials still show smaller effects over placebo than less precise trials.
2) Results from German-language countries are considerably more favourable for hypericum than trials from other countries.[6]

Standardized extracts are generally available over the counter, though in some countries (such as the Republic of Ireland) a prescription is required. Extracts are usually in tablet or capsule form, and also in teabags and tinctures. Herbalists are more likely to use a fluid extract than a tincture. Hypericum was prescribed in ancient Greece,[citation needed] and it has been used ever since.

Major depressive disorder

An analysis of twenty-nine clinical trials with more than five thousand patients was conducted by Cochrane Collaboration. The review concluded that extracts of St. John’s wort were superior to placebo in patients with major depression. St John’s wort had similar efficacy to standard antidepressants. The rate of side effects was half that of newer SSRI antidepressants and one fifth that of older tricyclic antidepressants.[6]

National Center for Complementary and Alternative Medicine (NCCAM) and other NIH-affiliated organizations hold that St John’s wort has minimal or no effects beyond placebo in the treatment of major depression.[7][8] This conclusion is based primarily on one trial of 340 volunteers, with negative outcome conducted by NCCAM.[9] The authors of the study themselves, as well as several others, pointed out the low assay sensitivity of this study, and how only limited conclusions can be drawn from its results.[10][11] The same study also indicated that sertraline (Zoloft) has no positive effects vs. the same placebo.

St. John’s wort has not been found to be effective for patients suffering from dysthymia, a less severe and more chronic variety of depression.[12]

Other medical uses

St. John’s wort is being studied for effectiveness in the treatment of certain somatoform disorders. Results from the initial studies are mixed and still inconclusive; some research has found no effectiveness, other research has found a slight lightening of symptoms. Further study is needed and is being performed.

A constituent chemical, hyperforin, may be useful for treatment of alcoholism, although dosage, safety and efficacy have not been studied.[13]Hyperforin has also been found to have antibacterial properties against gram-negative bacteria, although dosage, safety and efficacy has not been studied.[14]

randomized controlled trial of St John’s wort found no significant difference between it and placebo in the management of ADHD symptoms over eight weeks. However, the St. John’s Wort extract used in the study, originally confirmed to contain 0.3% hypericin, was allowed to degrade to levels of 0.13% hypericin and 0.14% hyperforin. Given that the level of hyperforin was not ascertained at the beginning of the study, and levels of both hyperforin and hypericin were well below that used in other studies, little can be determined based on this study alone.[15]

A research team from the Universidad Complutense de Madrid (UCM) published a study entitled, “Hypericum perforatum. Possible option against Parkinson’s disease“, which suggests that St John’s wort has antioxidant active ingredients that could help reduce the neuronal degeneration caused by the disease.[16]

Recent evidence suggests that daily treatment with St. Johns wort may improve the most common physical and behavioural symptoms associated with premenstrual syndrome.[17]

St John’s wort was found to be less effective than placebo, in a randomized, double-blind, placebo-controlled trial, for the treatment of irritable bowel syndrome.[18]

Externally, St John’s wort oil is used for the treatment of wounds, abrasions, and first degree burns.[19]

Adverse effects and drug interactions

St John’s wort is generally well tolerated, with an adverse effect profile similar to placebo.[20] The most common adverse effects reported are gastrointestinal symptoms, dizziness, confusion, tiredness and sedation.[21][22]

St John’s wort may rarely cause photosensitivity. This can lead to visual sensitivity to light and to sunburns in situations that would not normally cause them.[20] Related to this, recent studies concluded that the extract reacts with light, both visible and ultraviolet, to produce free radicals, molecules that can damage the cells of the body. These can react with vital proteins in the eye which, if damaged, precipitate out causing cataracts.[23]

Women who use the contraceptive implant Implanon are advised not to take St John’s Wort as it reduces the implant’s effectiveness.[citation needed]

Pharmacokinetic interactions

St John’s wort has been shown to cause multiple drug interactions through induction of the cytochrome P450 enzyme CYP3A4, but also CYP2C9. This results in the increased metabolism of those drugs, resulting in decreased concentration and clinical effect. The principal constituents thought to be responsible are hyperforin and amentoflavone.

St. John’s wort also has been shown to cause drug interactions through the induction of the P-glycoprotein (P-gp) efflux transporter. Increased P-gp expression results in decreased absorption and increased clearance of those drugs which leads to lower clinical concentrations and efficacy.[24]

{Information courtesy Wikipedia}