Background information
Echinacea is derived from the Greek word for hedhog. Native to North America, this purple coneflower is one of the world’s most widely used herbs for strengthening the immune system. It’s also America’s favourite herbal remedy, topping the list of best-selling herbs since 1996. Research shows it has the ability to raise the body’s resistance to bacterial and viral infections such as colds and flu. The best-studied and most widely used species are Echinacea purpurea, E. angustifolia, and E. pallida (McCaleb et al., 2000).
 
History and folk use
American Indians used echinacea intensively for illness and injuries. It was used externally for healing of wounds, burns, abscesses and insect bites; internally for infection, toothache and snake bites. It was first commercially introduced to Americans around 1870 as a blood purifier and was very popular among medical professionals in the late nineteenth century. After the introduction of antibiotics, it was forgotten. However, with the concern about the dangers of antibiotics overuse, and the increased interest in immune system disorders, such as chronic fatigue syndrome, AIDS and cancer, interest in echinacea was revived in 1980s. Since then, a great deal of scientific study has been done and impressive records of laboratory and clinical results were obtained for this native American herb (Murray, 1995; McCaleb, 2000). 
 
Parts used and Key uses
Root, flower, leaf and seed

Key uses: Boosts immune system Colds and flu Other minor infections (e.g. infections of ears, urinary tract, respiratory tract)
 
Popularity
The international recognition of echinacea’s function in boosting the immune system is well reflected in the German Commission E Monographs, where the pressed juice of Echinacea purpurea herb is recommended as supportive therapy for colds and chronic infections of respiratory and lower urinary tract. It was also indicated for poor healing wounds and chronic ulcerations. The root of Echinacea pallida is also recommended as supportive therapy for inflenza-like infections. In the United Kingdom, E. angustifolia root is approved for the treatment of chronic viral and bacterial infections, mild septicemia (blood poisoning), and skin complaints, including boils (McCaleb, 2000; Blumenthal, 1998).
 
Active constituents
Echinacea consists of a broad range of pharmacological active constituents, basically divided into seven categories:

• Polysaccharides
• Flavonoids
• Caffeic acid derivatives
• Essential oils
• Polyacetylenes
• Alkylamides
• Miscellaneous chemicals (Murray, 1995)

According to Stimple (1984), most of echinacea’s immune-enhancing properties are attributed to polysaccharides. One of echinacea’s polysaccharides, arabinogalactan, has shown significant ability to stimulate the immune system (Leuttig, 1989). However, most researchers believe that the synergistic effect among the constituents plays an essential role in producing the immune stimulation (McCaleb, 2000).
 
Recommended use
In herbal medicine, the recommended daily dosage of echinacea powdered extract is 900 mg daily (divided into three times) for adults. 
 
How it works
Immune system: There are two types of mechanisms by which our immune system protects against disease, simply described as (i) specific and (ii) non-specific immune defenses. For the first one, the immune cells, called lymphocytes, must recognise the specific invaders in order to destroy them. The non-specific defenses do not require the immune cells to recognise the invaders. Instead, invaders are destroyed by functions such as fever, release of anti-viral proteins called interferons, and phagocytosis, the process in which white blood cells consume invading organisms.

Echinacea activity is directed towards non-specific cellular immune system. It appears to boost the immune system by promoting the potency of infection-fighting cells such as macrophages, natural killer cells, and T lymphocytes. It may also increase the mobility of infection-fighting leukocytes (white blood cells) and stimulate phagocytosis. The herb also appears to stimulate the production of other important immune system components, including a group of inflammatory mediators called tumor necrosis factor (TNF) and interferon.
 
Health applications of echinacea
Echinacea exerts anti-inflammatory, immunostimulating, bactericidal, and wound healing action. As a whole, it promotes general well-being of the body in terms of disease prevention and supportive treatment. Specifically, the healthcare applications of echinacea include:

• Colds and flu: Echinacea has emerged as the most effective herbal prescription for the prevention and treatment of colds. It has become the most popular herbal remedy prescribed by healthcare professionals in Europe and the United States. Recent studies have proven its usefulness in this area (Schoneberger, 1992; Braunig et al, 1992).
• Infections: Various echinacea extracts or products have shown results in general infectious conditions like urinary tract infections. Such infections are normally treated with antifungal medications to kill the bugs. However, the underlying problem is indeed a weak immune system with insufficient defense. When used as a supportive therapy, echinacea has been proven to reduce the recurrent rate by 16.7% as compared to 60% when antifungal medication is used alone (Brown, 1996). Other types of infections where this herb may be of supportive therapy function include upper respiratory tract and ear infections. Cancer : Depressing the white blood cell levels is one of the side effects of cancer treatments (i.e. chemotherapy and radiotherapy). Several studies have demonstrated the stimulatory effects of echinacea on white blood cell counts in patients receiving radiation for cancer therapy (Murray, 1995).
• Other functions:
  • Wound healing: An 85% overall success rate in the treatment of inflammatory skin conditions such as wound of all kinds, eczema, abscesses and burns was found in several studies (Bauer, 1991).
  • Snake bites: Snake venom permeates the body through an enzyme, called hyaluronidase, which breaks down connective tissue in the ground substance between cells. Echinacea’s ability in inhibiting this enzyme might account for its efficacy in healing snake bites. 

Safety
Individuals who are allergic to daisies are advised not to take echinacea. Patients suffering from autoimmune illness, or other progressive systemic disease such as tuberculosis, multiple sclerosis, AIDS and HIV infection, need special precautions and should seek professional advice on the use of echinacea. In terms of drug interaction, it is advised not to take this herb together with methotrexate, anabolic steroids, and other hepatotoxic drugs (Brinker, 1998; Horowitz, 2000).

Note: Information provided is based on thorough research done on scientific and reliable sources. However, it is not meant to substitute for the advice provided by your own physician or other medical professional.
 
REFERENCES
1. Blumenthal, M., et al. (1998). The Complete German Commision E Monographs. The American Botanical Council. USA.

2. Bauer R and Wagner H: Echinacea species as potential immunostimulatory drugs. Econ Med Plant Res 5, 253-321, 1991.

3. Bratman, S., & Kroll, D. (1999). Natural Health Bible. Prima Health. USA.

4. Braunig B et al. Echinacea purpurea root for strengthening the immune response in flu-like infections. Zeitschrift Phytother 13:7-13, 1992.

5. Brinker, F. (1998). Herb Contradiction and Drug Interaction. Eclectic Medical Publications. USA.

6. Brown, D.J. (1996). Herbal Prescriptions for Better Health. Prima Health. USA.

7. Chevallier, A. (1996). The Encyclopedia of Medicinal Plants. Dorling Kindersley. UK.

8. Horowitz, S. (2000). Combining Supplements and Prescription Drugs – What Your Patients Should Know. Alternative & Complementary Therapies – August 2000, p. 177-183. USA.

9. Leuttig B, et al.: Macrophage activation by the polysaccharide arabinogalactan isolated from plant cell cultures of Echinacea purpurea. J Natl Cancer Inst 81:669-675, 1989.

10. McCaleb, R.S., Leigh, E., & Morien, K. (2000). The Encylopedia of Popular Herbs. Prima Health. USA.

11. Milam, L.J. (1999). Ginkgo Biloba.

12. Murray, M.T. (1995). The Healing Power of Herb. Prima Health. USA.

13. Schoenberger D: The influence of immune-stimulating effects of pressed juice from Echinacea purpurea on the course and severity of colds. Forum Immunol 8:2-12, 1992.

14. Stimpel M, Proksch A, et al.: Macrophage activation and induction of macrophage cytotoxicity by purified polysaccharide fractions from the plant Echinacea purpurea. Infect immunity 46:845 – 849, 1984.