The focus of this report is Astragalus membranaceus, an herb native to northern China and Mongolia that has stalks of yellow pea-like flowers (Oster, 1999:59). Some common names for Astragalus are huang qi, (Chinese) yellow leader and milk vetch (English), hwanggi (Korean) and ogi (Japanese) (AMR, 203:72). A. membranaceus belongs to the pea plant family Papilionaceae (www.ageless.co.za, 2005), and has a thick root with a yellowish, fibrous skin that has a slightly licorice taste (UMMCCMPR, 204, web). It is the dried root of A. membranaceus that is used medicinally, and it is usually harvested from 4‑5 year old plants (UMMCCMPR, 204 web). After briefly outlining the history of the medicinal use of A. membranaeeus, I will devote the rest of this paper to describing the herb's major uses and constituents, and will discuss its possible contraindications and recommended therapeutic dosages.
The great Chinese Emperor Shen Nung first discovered Astragalus membranaceus around 5000 years ago (Thompson, 201:2). According to Thompson, the Emperor's court preserved his knowledge and findings, enabling hundreds of generations of Chinese doctors to learn and expand upon. Westerners began to realize the medicinal importance of Astragalus membranaceus during the 1800's. Dr. Alexander van Bunge, a Russian physician who studied East Asian plants, first described the species for the West in 1868.
Same of the herb's popularity may be attributed to extensive scientific study that began in the 1970s, confirming the ability of Astragalus to stimulate the immune system, fight bacteria, viruses and inflammation, protect the liver, and act as a diuretic and adaptogen; a substance that "has nonspecific actions and causes minimal disruption to the body while normalizing body functions, no matter the condition or disease " (Thompson, 201:2). Astragalus membranaceus has also been shown to enhance circulation (AMR, 203:73), to successfully treat general digestive disturbances, including diarrhea, gas and bloating (UMMCCMPR, 2004 web), and to tonify the lungs (AMR, 203:72). It helps fight lung infections, by keeping viruses from gaining a foothold in the respiratory system (www.rd.com, 2005), and hence is helpful for people suffering from respiratory disorders such as asthma. Astragalus also has an adaptogenic effect on the kidneys (AMR, 1998:343; and Thompson, 201:2). Thus, it is useful for treating bladder infections caused by Proteus bacteria, and is of value in fighting the formation of kidney stones (www.ageless.co.za, 2005). Other medical conditions that may be treated with Astragalus are persistent infections, wounds, fever, burns, night sweats, chronic fatigue, anemia, uterine bleeding, stomach ulcers and abscesses (UMMCCMPR, 204 web). Finally, Astragalus is used to help male infertility, by improving sperm motility (AMR, 1998:75-76).
The immune restoring and strengthening uses of Astragalous membranaceus have been well documented (AMR, 203:73‑75; and AMR, 1998:33&340). Clinical trials have shown its benefits in generally impaired immunity, adjunctive cancer treatment, and viral infections, including the common cold and cervical erosion associated with Herpes simplex (AMR, 2003:73). Astragalus increases interferon production and makes some cancer medication more effective, thereby allowing less toxic dosages to be used in treatment. Concurrently, Astragalus reduces the side effects of steroid therapy and counteracts the immunosuppressive effects of chemotherapy and radiation (Landis, 199'7:136). It is used by cancer patients undergoing radiation as a supportive measure to prevent liver damage, as Astragalus exhibits good liver protecting qualities (www.ageless.co.za, 2005).
Some of the best evidence to date for the powerful immunostimulant effects of Astragalus comes from the University of Texas Medical Center in Houston. There, scientists tested damaged immune system cells from cancer patients, compared against cells from the blood of normal human subjects. Astragalus extracts were able to completely restore the function of cancer patients' immune cells. In some cases, the compromised cells were stimulated to greater activity than those from normal human subjects. The study concluded, "a complete immune restoration can be achieved by using a fractionated extract of A. membranaceus, a traditional Chinese medicinal herb found to possess immune restorative activity in vitro." (Landis, 1997;:136).
How does Astragalus membranaceus stimulate the immune system? First, it increases the number of stem cells in bone marrow and lymph tissue and encourages their development into active immune cells (AMR, 2003:73). In fact, Astragalus acts as an antioxidant, helping the body correct or prevent cell damage caused by free radicals (www.rd.com, 2005). It strengthens and boosts the immune system by improving the ability of macrophages (type of white blood cells) to fight and devour bacteria, fungi and viruses, and is also thought to promote the production of interferon in the body. (www.ageless.co.za, 2005) and enhances NK and T cell function (AMR, 2003:73).
The significant immune‑boosting effects of Astragalus membranaceus are due to its main constituents, which include polysaccharides, saponins, flavonoids, amino acids, and trace minerals (AMR, 2003:72). Some other important components of the herb are triterpene glycosides (e.g. astragaloides, I-VII), betaine, B-sitosterol, choline, dimethoxyisoflavone, gluconic acid; and kumatakanin (Thompson, 2001:3 and Balch, 1990:47). The flavonoids, saponins and polysaccharides found in Astragalus root help minimize free radical damage to membranes (AMR, 2003:73). Saponins are antioxidant compounds, and one saponin in Astragalus is reported to be especially protective of the liver (Landis, 1997:136). In one study performed in Shanghai, doctors showed that compounds from the root of Astragalus could protect heart cells from damage caused by the Coxsackie B virus. In one experiment, people suffering from this viral infection not only improved, but also showed enhanced resistance to the common cold (www.organicfood.co.uk, 2005). Astragalus helps improve circulation after a heart attack and helps protect the heart tissues. It has been found in tests to relieve angina pain, without the side effects of medicine normally used for this purpose (www.ageless.co.za, 2005). In diabetics, Astragalous is used to improve not only blood flow, but also to help improve fasting blood sugar levels (www.ageless.co.za, 2005).
Regarding concerns over the herb's possible toxicity, overall, Astragalus membranaceus is very safe, and doses as high as 100g/kg of the raw herb have been given to rats with no adverse effects (AMR, 1998:341).Astragalus membranaceus has no known side effects and can be used safely even in individuals who may not tolerate many other supplements, but pregnant or breastfeeding women should consult with a physician before using the herb (UMMCCMPR, 2004 web). Astragalus membranaceus should not be used without first talking to a healthcare provider if one is taking antiviral medications; this is because the herb may increase the effects of some antiviral medications such as acyclovir and interferon. Additionally, A. membranaceus may counteract the immune-suppressing effects of cyclophosphamide, a medication used to reduce the chances of rejection in transplant recipients (UMMCCMPR, 2004 web). Astragalus may be used in children to support the immune system, but should not be used if the child has a fever (UMMCCMPR, 2004 web). Finally, Tillotsin cautions that Astragalus may create nervousness and headache and even raise blood pressure in patients with heat signs or hypertension (Tillotsin, 2001:102).
Astragalus membranaceus preparations may be used in a variety of forms: capsules or tablets for internal use, injectable forms for use in clinical settings, or ointments for application to the skin (UMMCCMPR, 2004 web). Dr. Andrew Weil recommends looking for products standardized to 15% polysaccharides (www.drweil.com, 2005). He states that a usual dose is 2 capsules or tablets 2x/day, unless the product specifies otherwise. With tinctures, a dosage of 1 dropperful in tea or water 3x/day is recommended. Astragalus membranaceus is best used in small doses over a long period of time for prevention of infection (Tillotsin, 2001:102).
In conclusion, Astragalous membranaceus is an exceedingly powerful and useful herb, with extensive medical applications. Hopefully it will continue to be the focus of extensive scientific research, so that people dealing with diverse health conditions may benefit from its use in integrative medicine.
Bibliography
Books:
Balch, M.D., James F. and Balch, C.N.C., Phyllis. A Prescription For Nutritional Healing. New York: Avery Publishing Group, Inc., 1990.
Landis, Robyn. Herbal Defense. New York: Warner Books, Inc., 1997.
Mindell, R., Ph.D., Earl. New Herb Bible. New York: Simon & Schuster, 2000.
Oster, Maggie. Ortho's All About Herbs. Des Moines: Meredith Corp., 1999.
Tillotsin, Ph.D., A.H.G., D.Ay., Alan Keith. The One Earth Herbal Sourcebook. New York: Kensington Publishing Corp., 2001.
Magazine Articles:
Monograph. "Astragalus membranaceus." Alternative Medicine Review (AMR). V8, #l, 2003:72‑77.
Sinclair, N.D., L.Ac., Steven. "Chinese Herbs: A Clinical Review of Astragalus, Ligusticum, and Schizandrae." Alternative Medicine Review (AMR). V3, #5, 1998:338‑344.
Web Articles:
Thompson, Katrina. "The Healing Plant: Astragalus membranaceous." 2001:1‑4. http:://www.cancersalves.com/cheeklist/astragalus.html.
University of Maryland Medical Center Complementary Medicine Program Review (UMMCCMPR), 2004 hU://www.edu/altmed/ConsHerbs/Astraaalusch.html.
Websites:
www.herbalhouse.co.nz, 2005
www.drweil.com/u/Home/, 2005
www.apeless.co.za, 2005
www.rd.com, 2005
www.organicfood.co.uk, 2005
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