Echinacea

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This article is about the flowering plant. For Superorder Echinacea (Echinodermata) see Sea urchin

Echinacea
Echinacea purpurea
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Tribe: Heliantheae Genus: Echinacea
Species
See text

Echinacea is a genus consisting of nine species of flowering plants in the Family Asteraceae, all native to eastern North America.

The genus name is derived from the Greek echino, meaning "spiny", due to the spiny central disk. They are herbaceous, drought-tolerant perennial plants growing to 1 or 2 m in height. The leaves are lanceolate to elliptic, 10-20 cm long and 1.5-10 cm broad. Like all Asteraceae, the flowers are a composite inflorescence, with purple (rarely yellow or white) florets arranged in a prominent, somewhat cone-shaped head; "cone-shaped" because the petals of the outer ray florets tend to point downward (are reflexed) once the flower head opens, thus forming a cone. Studies have both proved and disproved the effectiveness of Echinacea in combating common diseases such as the cold.

The species of Echinacea are:

• Echinacea angustifolia - Narrow-leaf Coneflower
• Echinacea atrorubens - Topeka Purple Coneflower
• Echinacea laevigata - Smooth Coneflower, Smooth Purple Coneflower
• Echinacea pallida - Pale Purple Coneflower
• Echinacea paradoxa - Yellow Coneflower, Bush's Purple Coneflower
• Echinacea purpurea - Purple Coneflower, Eastern Purple Coneflower
• Echinacea singuinea - Singuine Purple Coneflower
• Echinacea simulata - Wavyleaf Purple Coneflower
• Echinacea tennesseensis - Tennessee Coneflower

[edit] Uses

Some species of Echinacea, notably P. purpurea, E. angustifolia, and E. pallida, are grown as ornamental plants in gardens They tolerate a wide variety of conditions, maintain attractive foliage throughout the season, and multiply rapidly. Appropriate species are used in prairie restorations. Some species are used by domestic stock for forage; an abundance of these plants on rangeland purportedly indicates "good health".

Echinacea rhizome was used by North American Plains Indians, perhaps more than most other plants, for various herbal remedies. In the 1930s "Echinacea" became popular in both Europe and America as a herbal medicine. Echinacea has been popularly attributed with the ability to boost the body's immune system and ward off infections, particularly the common cold. Depending on which species is used, herbal medicinals can be prepared from the above-ground parts and/or the root. It is not known which of echinacea's many chemical components might be responsible for its touted health benefits, although all species possess compounds of a chemical class called phenols (as do most other plants). Cichoric and caftaric acids are phenols that are present in E. purpurea; echinacoside is a phenol found in higher levels within E. angustifolia and E. pallida roots. When making herbal remedies, these phenols can serve as markers to evaluate the quantity of echinacea in the product. Other constituents that may be important include alcamides and polysaccharides.

A medical study (Taylor et al. 2003^[1].) demonstrated that when echinacea products made from the entire plant (not just the root) were taken after the second cold symptom appeared they provided no measurable beneficial effect for children in treating the severity or duration of symptoms caused by the common cold virus. Studies by the University of Virginia School of Medicine (Turner, 2005 ^[2]) confirmed these results, and added that Echinacea had no clinically significant effects on the common cold even if taken immediately upon infection, or as a prophylaxis starting a week prior to symptoms of infection. However, a University of Maryland review of available studies concluded that Echinacea, when taken at first sign of a cold, reduced cold symptoms or shortened their duration. This conclusion was based on 13 European studies. The University of Maryland study also found that three of four studies concluded that taking Echinacea to prevent a cold was ineffective. Echinacea may, however, be useful when treating Athlete's foot with Econazole, or in cancer treatment^[3].

Leading herbalists claim that many studies do not distinguish between alcohol-based echinacea tinctures, which retain potency for up to seven years after production, and capsules containing the dried herb, which lose their efficacy over time. Proponents of echinacea assert that is not a "one-dose" treatment, and that in order to work effectively, a dose should be taken at the very first sign of a cold symptom. Subsequent doses must be taken every two to four hours after the first dose, including every two to four hours during the overnight sleeping period, until the cold symptoms have disappeared (generally within 24 hours.) The scientific studies stated above appear to dimiss these claims as ad hoc rationalising; if the cold doesn't go away when expected, the patient can always be blamed for not following the strict regimen, and the product is never to blame. This is known as subjective validation.

Not all species of Echinacea are equally effective. A Cochrane review of the published studies ^[4] has found that there is some evidence of benefit in the treatment (but not prevention) of the common cold by the aerial parts of Echinacea purpura; other formulations of the plant did not show the same effect, and no formulation was effective for prevention.

Echinacea herbals should not be taken by persons with progressive systemic and auto-immune disorders such as tuberculosis, leicosis, connective tissue disorders, collagenosis, and related diseases such as lupus erythematosus, according to the German Kommission E. Its use in AIDS or against opportunistic infections in AIDS patients is controversial: the Kommission E recommend against it. ^[5]. It should not be used with other known hepatotoxic drugs such as anabolic steroids, amiodarone (Pacerone^® or Cordarone^®), methotrexate, or ketoconazole (Nizoral^®) ^[6].

[edit] Notes and references