The plant Hypericum perforatum is native to Europe, the U.S.A. and parts of Canada. It grows aggressively in dry ground, usually to a height of one to two feet, but can grow as high as five feet on the Pacific Coast. A perennial, its bright yellow blossoms appear around the birthday of St. John the Baptist (June 24th), which explains its common name, St. John's Wort.

St. John's Wort has been used medicinally since the Middle Ages for a variety of complaints; however, the predominant use of current interest is for treating depression. In order to appreciate how St. John's Wort may help depression, it is important to understand the nature of the illness itself.

What is Clinical Depression?

In contrast to situational, or reactive depression, where an individual is responding to a serious event such as the death of a loved one, clinical depression can be medically defined. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), a depressive episode involves at least two weeks of depressed mood and markedly diminished interest or pleasure in most or all activities (like work, friends, food, sex, hobbies and entertainment). Increased severity of depression includes three or more symptoms involving changes in appetite, weight, sleep patterns or psychomotor activity, feelings of hopelessness, worthlessness or guilt, lethargy, the inability to concentrate, and/or suicidal ideation. Clearly, clinical depression isn't just a few days of the 'blues'.

Currently, it is believed the most common reason for depression is an imbalance of chemicals in the brain called neurotransmitters. Nerve impulses travel 'electrically' along nerve fibres. In order for the impulse to transfer from one fibre to the next, a chemical (neurotransmitter) is released and floats across the microscopic gap between the fibres (called a synapse), to bind to the next fibre, and stimulate a new electrical impulse to continue the 'message'. Once the message is transmitted, the sending nerve stops the stimulation of the receiving nerve by actively reabsorbing the neurotransmitter or destroying it with enzymes such as monamine oxidase (MAO).

The brain uses a number of neurotransmitters (including norepinephrine, epinephrine, dopamine and serotonin) which, combined with the actual complexity of the reaction taking place, means there are plenty of opportunities for things to go wrong, including:

• the sending nerve may not make enough neurotransmitters in the first place,
• there may not be enough binding sites on the receiving nerve,
• there may be too much enzyme destroying the neurotransmitter, or
• the neurotransmitter may be reabsorbed too quickly.

This range of possible actions makes it difficult to know exactly what is going wrong in a given individual; however the treatments can be aimed at one or several of these problems. Regardless of the action, the result is that the nerve impulses do not seem to be crossing this synapse properly. The goal of treatment is to improve this transmission.

Is St. John's Wort Really "Nature's Prozac"?

NO! St. John's Wort lacks the power and selectiveness of modern antidepressants like Prozac. It could be catastrophic to attempt to treat a major clinical depression with St. John's Wort; however, in cases of mild depression it may hold some value.

The way St. John's Wort works is the subject of many studies - most with conflicting results. The best known component of the plant is a compound called hypericin, but there are at least ten other potentially active constituents (including pseudohypericin, flavonoids, phenols, xanthines, tannins and terpines), which may be part of the reason for confusion. St. John's Wort seems to block the enzymes that breakdown neurotransmitters (called "MAO inhibition"), and reduce the reabsorption of neurotransmitters (similar to what drugs like Prozac do). No matter the varying opinions over how it works, most studies do agree that St. John's Wort demonstrates the ability to improve mild depression with a relatively low incidence of side effects.

Dosage

St. John's Wort must be harvested in the summer and dried immediately to preserve its maximum potency. Hypericin, once extracted, is deep red in colour and capable of staining skin and fabric. Commercial products are available in a variety of forms, but only those standardized to hypericin content (usually 0.3%) are recommended. The customary dose is 3O0mg, three times daily, and users should bear in mind that St. John's Wort, like any medication for depression, may take several weeks to show results.

Side Effects

St. John's Wort appears to be well-tolerated, but side effects may include gastrointestinal symptoms, fatigue, sedation or restlessness. There also appears to be a risk of photosensitivity, which produces a rash, so patients should avoid midday sun exposure and use a sunscreen. Although actual incidences have not been noted in the literature, the proposed MAO inhibitory activity of St. John's Wort could potentially cause interaction with foods that are high in tyramine (aged cheeses, beer, wine and dry sausage). Dietary restrictions are probably unnecessary, but users should not exceed the recommended dose, and should avoid consuming excessive quantities of these foods while taking St. John's Wort.

Patients already taking prescription antidepressants should not take St. John's Wort simultaneously because it is possible to induce Serotonin Syndrome - a serious condition characterized by confusion, chills, fever and hyperactive reflexes, and capable of progressing to seizures or coma. These people should discuss their interest in St. John's Wort with their physician to get more information.

Other Uses

Historically, St. John's Wort has been used to treat gastritis, insomnia, and as a diuretic. It can be applied to relieve inflammation and hemorrhoids, and promote healing. Although none of these uses have been scientifically demonstrated to be effective, it certainly does appear to have a role in the treatment of mild depression. Studies are also underway to investigate its use for the treatment of anxiety disorders and, through its apparent anti-viral action, there are hopes it will prove to be effective against viruses such as HIV, influenza, herpes and hepatitis. Watch for further news of this exciting drug in the years to come.

Compiled by Tracie & William Der
Island Apothecary, Gabriola Island, B.C.
Edited by Megan Stiles
Last Reviewed: September 2001