From Wikipedia, the free encyclopedia
- This article is about the flowering plant. For Superorder Echinacea (Echinodermata) see Sea urchin
The genus name is 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:
The spiny flower center from which the name derives
Uses
Echinacea is an herb native to prairie habitats in the United States. Some species of
Echinacea, notably
P. purpurea,
E. angustifolia, and
E. pallida, are grown as
ornamental plants in gardens
[1] 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 angustifolia rhizome was used by
North American Plains Indians, perhaps more than most other plants, for various herbal remedies. Echinacea was one of the basic antimicrobial herbs of
Eclectic medicine in the mid 1800s through the early 1900s and its use was documented for snakebite and anthrax. 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.
This herb is sometimes used as a natural antibiotic and immune system stimulator, helping to build resistance to colds, flu and infections. It is thought to increase the production of white blood cells, and improve the lymph glands. The tea from this herb has been used for infections and has been used in treating skin cancers and other cancers.
Constituents
The full spectrum of echinacea's chemical components responsible for its health benefits are not well deliniated. Like most
crude drugs from plant or animal origin, the constituent base is complex and some parts may be directly antimicrobial while others work at stimulating or modulating different parts of the immune system. All species possess compounds of a chemical class called
phenols (as do many 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.
Studies
A medical study (Taylor et al. 2003
[2].) 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. Dosage however was about a third of what clinical herbalists routinely use, and the leaves and stems are not known to be clinically effective. Studies by the University of Virginia School of Medicine (Turner, 2005
[3]) 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.
[4] The University of Maryland study also found that three of four studies concluded that taking
Echinacea to prevent a cold was ineffective, although including studies that use subclinical doses, the wrong part or unassayed material will bias such conclusions. Echinacea may, however, be useful when treating
Athlete's foot with
Econazole, or in cancer treatment
[5].
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. Capsules not only lose strength, but must be digested in the stomach while alcohol tinctures enter the lymphatic system through the tongue. 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 disagree with 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
[6] 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.
[7]. It should not be used with other known hepatotoxic drugs such as
anabolic steroids,
amiodarone (
Pacerone® or
Cordarone®),
methotrexate, or
ketoconazole (
Nizoral®)
[8].
Notes and references
- ^ http://www.ars.usda.gov/SP2UserFiles/Place/36251200/Posters/Echinacea_poster2.pdf
- ^ "Efficacy and safety of echinacea in treating upper respiratory tract infections in children: a randomized controlled trial", Taylor, J. A., et al. 2003., Journal of the American Medical Association 2003 Dec 3;290(21):2824-30
- ^ "An evaluation of Echinaceae angustifolia in experimental rhinovirus infections." Turner, R. B. et al. 2005., New England Journal of Medicine 353: 341-348..
- ^ Paul Bergner. Healing Power of Echinacea and Goldenseal and Other Immune System Herbs (The Healing Power)1997
- ^ University of Maryland Echinacea Study Review
- ^ Linde K, et al. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. 2006 Jan 25;(1):CD000530
- ^ Mayo Clinic report
- ^ Herbal medicines. "Selected clinical considerations focusing on known or potential drug-herb interactions.", Miller, Lucinda G., 1998, Archives of Internal Medicine 158: 2200-2211.
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