Echinacea

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Echinacea Purpea, a.k.a. coneflower. Its name is derived from the Greek echinos, meaning "hedgehog", due to resemblance of the central part of the flowering head to the spines of a coiled hedgehog, superimposed.

Echinacea is a genus of nine perennial herbs native to central and eastern North America. The genus is a member of the Asteraceae or sunflower family and a member of the large tribe Heliantheae within the Asteraceae. Three members of the genus are known principally for their uses as topical and internal herbal remedies. The plant is also appreciated and cultivated for its ornamental value as a garden flower.

Echinacea contains the glycoside ecinacoside, alkamides, inulins, and resins.[1] The plant has a long history as an herbal medicine, is popular today as such, and has been the subject of numerous scientific studies in these regards, with varied results.[2]

The genus contains nine species including E. angustifolia (blacksamson echinacea) and E. purpurea (eastern purple coneflower). E. angustifolia grows in the central United States.[3]

E. purpurea grows in the eastern United States except for northern New England.[4]

Botany

The echinacea genus is in the aster family.[5]

Phytochemicals

The chemicals contained in the upper part of the plant and its root differ considerably. The above-ground parts of the plant are known to contain high amounts of polysaccharides, which have been shown to trigger immune system activity, while the roots contain high concentrations of volatile oils (odorous compounds).[6]

Traditional uses

Archaeological digs suggest that certain Native Americans used echinacea for at least 400 years as a sort of "cure all", and for infections and wounds.[7] In the European West, echinacea has been used to treat scarlet fever, syphilis, malaria, blood poisoning, and diphtheria. In the United States, it was especially popular during the 18th and 19th centuries, although usages declined after the introduction of antibiotics. In Germany, echinacea became increasingly popular through the 20th century.[6] Interest in the herb in the United States renewed after passage of the Dietary Supplement Health and Education Act of 1994, which loosened regulatory control over the marketing and sale of herbal remedies,[8] with just one company reporting over US $10-million in sales two years later.[9] Herbal practitioners today may recommend echinacea for urinary tract infections, vaginal yeast (candida) infections, ear infections (otitits media), athlete's foot (tinea pedis), sinusitis, hay fever (allergic rhinitis), and slow-healing wounds.[6]

Role in modern health care

German scientists have conducted the majority of research on echinacea. The above-ground parts of Echinacea purpurea are approved by the German government to treat colds, upper respiratory tract infections, urinary tract infections, and slow-healing wounds, while Echinacea pallida root is approved to treat flu-like infections.[6]

According to randomized controlled trials and most systematic reviews conducted within the United States, however, there is insufficient evidence to warrant a role for echinacea in treating or preventing the common cold.[10][11][12][13] An additional randomized controlled trial found no benefit in experimentally induced rhinovirus infection.[14] A meta-analysis by the Cochrane Collaboration concluded there may be a role for the aerial parts of Echinacea purpurea that needs further study.[12] More recently, a meta-analysis conducted in the U.S concluded that echinacea may help in both prevention and reducing duration.[15] This meta-analysis did not study the effect on the severity of cold symptoms. This is difficult to interpret as two of the best studies,[11][14] that used placebos designed to mimic the taste and texture of the echinacea, were both negative. In addition, this meta-analysis reported funnel plot asymmetry which notes its results may be affected by publication bias against negative studies.

Of note, in the field of complementary and alternative medicine (CAM), publication bias or bias in interpretation of studies, may be more common than in other disciplines. This may be more likely in studies published in languages of than English.[16] This may be due to typical CAM studies being smaller than trials of conventional medicine[16]. According to two European analyses, both including German authors and one from the German Cochrane Center, this bias may be especially prevalent in German publications.[17][18]

Both German and U.S. studies have suggested echinacea may be efficacious in treating upper respiratory infections (URIs).[6]

References

  1. Anonymous (2022), Echinacea (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. University of Maryland Medical Center. Echinacea. University of Maryland Medical Center. Retrieved on 2008-02-03.
  3. USDA. PLANTS Profile for Echinacea angustifolia (blacksamson echinacea). USDA PLANTS. Retrieved on 2008-02-03.
  4. USDA. PLANTS Profile for Echinacea purpurea (eastern purple coneflower). USDA PLANTS. Retrieved on 2008-02-03.
  5. USDA. Classification for Kingdom Plantae Down to Genus Echinacea Moench. USDA Plants. Retrieved on 2008-02-03.
  6. 6.0 6.1 6.2 6.3 6.4 University of Maryland Medical Center. Echinacea (HTML). University of Maryland Medical Center. Retrieved on 2008-02-03.
  7. See Andrea T Borchers, et al. "Inflammation and Native American medicine: the role of botanicals". Am. J. Clinical Nutrition, Aug 2000; 72: 339 - 347. Available online Also Archived by WebCite®. The people groups mentioned are the Cheyenne, Dakota, Fox, Kiowa, Montana Indians, Omaha, Pawnee, Ponca, Teton Sioux, and Winnebago.
  8. Turner, Ronald B. "Echinacea for the Common Cold: Can Alternative Medicine Be Evidence-Based Medicine?" Annals of Internal Medicine, 12/17/2002, Vol. 137 Issue 12, p1001-1002, 2p; (AN 8689863).
  9. Pollock, Ellen Joan and Moss, Michael. Wall Street Journal (Eastern Edition); 1/20/97, Vol. 229 Issue 13, pA1, 1bw.
  10. Yale SH, Liu K (2004). "Echinacea purpurea therapy for the treatment of the common cold: a randomized, double-blind, placebo-controlled clinical trial". Arch. Intern. Med. 164 (11): 1237–41. DOI:10.1001/archinte.164.11.1237. PMID 15197051. Research Blogging.
  11. 11.0 11.1 Barrett BP, Brown RL, Locken K, Maberry R, Bobula JA, D'Alessio D (2002). "Treatment of the common cold with unrefined echinacea. A randomized, double-blind, placebo-controlled trial". Ann. Intern. Med. 137 (12): 939–46. PMID 12484708. [e]
  12. 12.0 12.1 Linde K, Barrett B, Wölkart K, Bauer R, Melchart D (2006). "Echinacea for preventing and treating the common cold". Cochrane Database Syst Rev (1): CD000530. DOI:10.1002/14651858.CD000530.pub2. PMID 16437427. Research Blogging. “some evidence that preparations based on the aerial parts of Echinacea purpurea might be effective for the early treatment of colds in adults but results are not fully consistent”
  13. Arroll B (2006). "Common cold". Clin Evid (15): 2006–14. PMID 16973075. [e]
  14. 14.0 14.1 Turner RB, Bauer R, Woelkart K, Hulsey TC, Gangemi JD (2005). "An evaluation of Echinacea angustifolia in experimental rhinovirus infections". N. Engl. J. Med. 353 (4): 341–8. DOI:10.1056/NEJMoa044441. PMID 16049208. Research Blogging.
  15. Shah SA, Sander S, White CM, Rinaldi M, Coleman CI (2007). "Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis". Lancet Infect Dis 7 (7): 473–80. DOI:10.1016/S1473-3099(07)70160-3. PMID 17597571. Research Blogging.
  16. 16.0 16.1 Pham B, Klassen TP, Lawson ML, Moher D (2005). "Language of publication restrictions in systematic reviews gave different results depending on whether the intervention was conventional or complementary". J Clin Epidemiol 58 (8): 769–76. PMID 16086467. [e]
  17. Galandi D, Schwarzer G, Antes G (2006). "The demise of the randomised controlled trial: bibliometric study of the German-language health care literature, 1948 to 2004". BMC Med Res Methodol 6: 30. DOI:10.1186/1471-2288-6-30. PMID 16824217. Research Blogging.
  18. Lancet. 1997. Language bias in randomised controlled trials published in English and German. http://pubmed.gov/16086467