Background Echinacea, Astragalus and Glycyrrhiza have been used historically and are used today to enhance the immune system. Echninacea has been used for centuries by Native Americans, and is one of the most commonly used herbs for respiratory tract infections. Astragalus is primarly used in Chinese medicine as a tonic, to prevent colds and aid the spleen and lungs. Glycyrrhiza (licorice) has been used medicinally since the beginning of recorded history, and is widely used today in Indian and Chinese medicine. For centuries the herb has been used to treat respiratory, gastrointestinal and cardiovascular conditions.
Most of the existing research into the mechanism of these herbs has been conducted in animal models. To measure the effects in humans, researchers must examine the impact the herbs have on cell activation in lymphocytes. Lymphocytes are a type of white blood cell and come in three forms: B cells, which make antibodies that bind to a virus or micro-organism and then destroy it; CD4 T cells, which coordinate the immune system’s response; and CD8 T cells, which kill cells that become infected.
A New Study The authors of a new study entitled, “The Effect of Echinacea purpurea, Astragalus membranaceus, and Glycyrrhiza glabra Immune Cell Activation and Proliferation in Humans” are Julie Brush, ND, Elissa Mendenhall, ND, Alan Guggenheim, Tracy Chan, ND, Erin Connelly, MA, Richard Barrett, ND, and Heather Zwickey, Ph.D., all from the Helfgott Research Institute, National College of Natural Medicine, Portland, OR; (Note: Dr. Zwickey is also Director of the Helfgott Research Institute); Amala Soumyanath, Ph.D., from the Oregon Health and Science University, Portland, OR; and Randal Buresh, from Oregon’s Wild Harvest, Sandy, OR. An American Medical Association Seed Grant, Helfgott Research Seed Fund Grant, and Oregon’s Wild Harvest funded this study.
Dr. Zwickey will present her team’s findings at the 21st Annual Meeting of the American Association of Naturopathic Physicians (http://www.Naturopathic.org), being held August 9-12, 2006 at the Oregon Convention Center, Portland, OR.
Methodology Sixteen healthy subjects participated in a double-blind, placebo controlled, randomized clinical trial. The subjects were randomized to solutions of Echinacea only, Astragalus only, Glycyrrhiza only, the combination of all three in equal parts, and placebo. The subjects received a 7.5 ml dose twice a day for seven days. Peripheral blood was drawn from the subjects three times: before ingesting the herbal solution, after 24 hours, and seven days after herbal ingestion. White blood cells were separated from whole blood and analyzed to determine immune activation through the cell surface protein CD69. Immune regulation was determined by CD25 expression on CD4 T cells.
Results The researchers found that:
- Echinacea and Glycyrrhiza were able to stimulate proliferation of CD4 T cells, CD8 T cells and NK cells when administered orally to the study subjects.
- All three herbs -- administered either singly or in combination -- were able to activate CD8 T cells. Astragalus caused the most activation.
- Glycyrrhiza was able to stimulate NK activation.
- All the subjects who received Echinacea tincture showed CD25 activation at 24 hours compared to 0 hours, which persisted at seven days.
- Of great interest to the researchers was the simultaneous expression of activation (CD69) and regulation (CD25), present in the same patients.
Conclusions The results demonstrate that Echinacea, Astragalus, and Glycyrrhiza herbal tinctures stimulate CD4 T and CD8 T cells. Thus, the authors believe that these herbs do work in enhancing the immune system, but are likely to be most effective when the essential medical qualities are applied in a certain application. The team also stated that this study, supported by the naturopathic and medical communities, demonstrates that further collaborative research on the use of the herbs in enhancing the body’s immune system is warranted.
The American Association of Naturopathic Physicians (AANP) was founded in 1985 to provide alternative methods for healing human diseases and disorders than have been traditionally offered in the United States. Members of the AANP must have graduated from one of North America’s six accredited graduate schools of naturopathic medicine.
Source: American Association of Naturopathic Physicians (AANP)