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St. John's Wort

Posting Date: 06/04/2002

Original Posting: 1/1/2000

St. John's wort has long been used in Europe for treating mood disorders and has become very popular in the United States.

The plant itself is a perennial native to Europe, but it has adapted well to North America and grows as a weed in many places. (Indeed, it is sometimes called klamath weed or goatweed.)

In the Middle Ages, people noticed that the attractive bright yellow flowers of this herb appeared most profusely (or perhaps made their first appearance) around the feast of John the Baptist at the end of June.

The flowers were gathered and soaked in olive oil. The oil turned bright red after a few weeks' time and was considered a powerful treatment for cuts and scrapes.

Many Crusaders carried "red oil" with them to use to heal the wounds of battle. The plant itself had a reputation going back to Greek and Roman times of being able to protect people against evil spells.

Active Ingredients

The parts of the plant used are the leaves and the flowering tips (flowers and buds) collected when the plant is blooming and dried quickly to preserve their potency.

Hypericin and related compounds, such as pseudohypericin, are characteristic components making up from 0.05 to 0.3 percent of the herb. Concentrations of hypericins differ with the variety of the plant and with how much of the lower leaves and stem are gathered.

St. John's wort also contains the flavonoids kaempferol, quercitin, amentoflavone, and luteolin, and quercitin glycosides hyperoside and rutin. Together these constituents make up from 2 to 4 percent of the plant material.

Nearly 10 percent of St. John's wort is composed of tannins, and approximately 1 percent is a volatile oil.

Up to 3 percent of the herb is hyperforin, a chemical structurally similar to an active ingredient of hops. In addition, St. John's wort contains bioflavones and small amounts of procyanidins.