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Astragalus

Other common name(s): milk vetch, huang qi, huang ch', ogi, hwanggi, bei qi, radix astragali, goat's horn, green dragon, locoweed

Scientific/medical name(s): Astragalus membranaceus

Description

Astragalus is a traditional Chinese herbal medicine taken from a plant known as Astragalus membranaceus, which is a type of bean (legume). The root is used in herbal remedies.

Overview

Animal studies and preliminary human clinical studies suggest that astragalus may improve immune system function and boost the effect of conventional immune therapy for some cancers. But available scientific evidence does not support claims that astragalus can prevent cancer, cure cancer, extend survival, or reduce side effects of conventional cancer treatment. There is some suggestion that it may enhance the effects of certain chemotherapy drugs, but this theory needs to be tested more thoroughly.

How is it promoted for use?

The herb is promoted to kill cancer cells, reduce the toxic effects of chemotherapy, help heal burns, protect against heart disease, fight the common cold, and help improve overall weakness. Proponents also claim astragalus can stimulate the spleen, liver, lungs, circulatory, and urinary system, and help treat arthritis, asthma, and nervous conditions. They further claim it can lower blood sugar levels and blood pressure.

What does it involve?

When dried, the root of the astragalus plant is sold in tea bags, tinctures, and capsules. It is also available as dried slices of the root and as a powder. In China, healers sometimes use the dried root in soups or roast the root in honey for use as a medicinal tonic. Astragalus is usually combined with other Chinese herbal remedies.

What is the history behind it?

For more than 2,000 years, Chinese herbalists have recommended astragalus to help the human body build up energy and resist diseases including cancer, heart disease, liver and kidney problems, and infections. It is the most commonly used herb in traditional Chinese medicine, though it is most often used with other herbs. Conventional medical researchers became interested in the possibility that astragalus might boost immune response and lessen the side effects of chemotherapy.

What is the evidence?

The scientific evidence for the ability of astragalus to enhance the immune system and fight diseases, including cancer and heart disease, comes mostly from lab and animal studies. Researchers at The University of Texas M.D. Anderson Cancer Center found that astragalus extract boosted the cell-destroying ability, or cytotoxicity, of the conventional immune system drug interleukin-2 (IL-2) by helping cells of the immune system. (This study was done using cells in the lab, not in humans.)

Astragalus partly restored the immune function of cells in test tubes. Some studies have suggested that it can reduce the length of colds. Astragalus may stimulate the body to produce interferons, a group of substances used by the body to defend against viral infections.

Though animal and laboratory studies show promise, more study is needed to find out if the results apply to humans. A few human studies of astragalus have been done, mostly in China, and some suggest that this herb might help the immune system cells in people who have cancer. But most experts who have reviewed these studies said that flaws in the way the most of this research was designed, conducted, or analyzed make it difficult to say if their results are valid. If the herb is found to boost immune system effects and help fight tumors, it may be helpful as an adjunct to chemotherapy or other cancer treatments.

A 2006 review of the most reliable studies of astragalus and lung cancer found some evidence that this herb might enhance the effects of platinum-based chemotherapy drugs such as cisplatin. The reviewers recommended that more rigorously designed studies be conducted. A non-randomized clinical trial of patients with lung cancer found no evidence that astragalus increased the effectiveness of a different type of chemotherapy drug, docetaxel.

The consensus of available scientific evidence does not support claims that astragalus can prevent or cure cancer in humans or decrease the toxic effects of chemotherapy or other conventional cancer treatments. Large-scale human trials are needed to learn about the benefits, if any, of astragalus in people with cancer.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Astragalus is generally thought to be safe. Reported side effects include belly bloating, loose stools, low blood pressure, and dehydration. People with autoimmune diseases (such as rheumatoid arthritis or lupus) or people taking drugs that suppress the immune system (such as corticosteroids or cyclosporin) should talk with their doctors before taking this herb.

There is some concern that astragalus might interfere with blood clotting, so some doctors say that it should not be taken before surgery or in people taking aspirin-like drugs or blood-thinning medicines. It may also affect blood pressure in some, so those taking blood pressure medicines may need to be watched more closely if they use this herb. There have also been reports of lowered blood sugar, which could be dangerous for those with diabetes or hypoglycemia.

Other potential interactions between herbs and medicines are possible, some of which may be dangerous. Always tell your doctor and pharmacist about the herbs you are taking.

Allergic reactions are rare. People who are allergic to other legumes (peas and beans) may be more likely to be allergic to astragalus. Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

Additional resources

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org ) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Cancer Treatments

Learning About New Ways to Prevent Cancer

American Cancer Society Operational Statement on Complementary and Alternative Methods of Cancer Management

References

Block KI, Mead MN. Immune system effects of echinacea, ginseng, and astragalus: a review. Integr Cancer Ther. 2003 Sep;2(3):247-67.

Cassileth BR, Rizvi N, Deng G, Yeung KS, Vickers A, Guillen S, Woo D, Coleton M, Kris MG. Safety and pharmacokinetic trial of docetaxel plus an Astragalus-based herbal formula for non-small cell lung cancer patients. Cancer Chemother Pharmacol. 2009; 65(1):67-71.

Chu DT, Lepe-Zuniga J, Wong WL, LaPushin R, Mavligit GM. Fractionated extract of Astragalus membranaceus, a Chinese medicinal herb, potentiates LAK cell cytotoxicity generated by a low dose of recombinant interleukin-2. J Clin Lab Immunol. 1988;26:183-187.

Cui R, He J, Wang B, et al. Suppressive effect of Astragalus membranaceus Bunge on chemical hepatocarcinogenesis in rats. Cancer Chemother Pharmacol. 2003;51:75-80.

Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 3rd ed. Montvale, NJ: Thomson PDR; 2004.

Khoo KS, Ang PT. Extract of Astragalus membranaceus and ligustrum lucidum does not prevent cyclophosphamide-induced myelosuppression. Singapore Med J. 1995;36:387-390.

Lau BH, Ruckle HC, Botolazzo T, Lui PD. Chinese medicinal herbs inhibit growth of murine renal cell carcinoma. Cancer Biother. 1994;9:153-161.

McCulloch M, See C, Shu XJ, Broffman M, Kramer A, Fan WY, Gao J, Leib W, Shieh K, Colfrod JM Jr. Astragalus-based Chinese herbs and platinum-based chemotherapy for advanced non-small-cell lung cancer: meta-analysis of randomized trials. J Clin Oncol. 2006:24:419-430.

Memorial Sloan-Kettering Cancer Center. Astralagus (updated 8/17/09). Accessed at www.mskcc.org/mskcc/html/69128.cfm on April 8, 2010.

Miller AL. Botanical influences on cardiovascular disease. Altern Med Rev. 1998;3:422-431.

National Center for Complementary and Alternative Medicine (NCCAM). Astragalus. Accessed at http://nccam.nih.gov/health/astragalus/ on April 9, 2010.

Rittenhouse JR, Lui PD, Lau BH. Chinese medicinal herbs reverse macrophage suppression induced by urological tumors. J Urol. 1991;146:486-490.

Taixiang W, Munro AJ, Guanjian L. Chinese medical herbs for chemotherapy side effects in colorectal cancer patients. Cochrane Database Syst Rev. 2005;(1):CD004540.

Wu P, Dugoua JJ, Eyawo O, Mills EJ. Traditional Chinese medicines in the treatment of hepatocellular cancers: a systematic review and meta-analysis. J Exp Clin Cancer Res. 2009 Aug 12;28:112.

Zhao KS, Mancini C, Doria G. Enhancement of the immune response in mice by Astragalus membranaceus extracts. Immunopharmacology. 1990;20:225-233.

Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 07/06/2010
Last Revised: 07/06/2010