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Other common
name(s): sweet root, licorice root
Scientific/medical
name(s): gan cao, Glycyrrhiza
glabra, Glycyrrhiza
uralensis
Description
Licorice is a perennial plant that grows in southern Europe,
Asia, and the Mediterranean. The dried roots and underground stems of
the plant are used in herbal remedies.
Overview
Licorice root is an ingredient in many traditional Chinese
herbal remedies. It also has been used in other countries to treat a
wide variety of health problems. However, it is linked to some fairly
serious side effects. Whole-herb licorice can cause an imbalance of
fluid and the mineral potassium in the body, which can lead to heart
rhythm problems, high blood pressure, muscle weakness, and even
paralysis. Although recent laboratory research has identified some
components that might be useful in cancer prevention or treatment,
there is almost no information available about their effectiveness in
humans. More research is needed to find out whether licorice extract
has any role in cancer prevention or treatment.
How is it promoted for use?
Licorice is promoted to treat peptic ulcers, eczema, skin
infections, cold sores, menopausal symptoms, liver disease, respiratory
ailments, inflammatory problems, chronic fatigue syndrome, AIDS, and
even cancer. It has also been promoted to relieve symptoms of
Addison’s disease, lower cholesterol and triglyceride levels,
strengthen the immune system, and treat hepatitis.
Many food products are widely available that contain traces of
licorice. Some licorice candy sold in the United States is actually
flavored with anise and does not contain licorice. Glycyrrhizin (an
active ingredient from the plant) is used as a flavoring in candy, gum,
cookies, beverages, and cough syrup. Licorice is also used as a
flavoring for tobacco products.
What does it involve?
Licorice is packaged as capsules, tablets, and as a liquid
extract. It can be purchased at grocery stores, health food stores, or
pharmacies. According to Commission E (Germany's regulatory agency for
herbs), the recommended dosage ranges from 200 to 600 milligrams for no
more than 4 weeks for peptic ulcers. Licorice is also an ingredient in
many traditional Chinese herbal formulations. The best known of these
are herbal products for prostate cancer treatment such as PC-HOPE and
PC-CARE. Because of its side effects, glycyrrhizin is removed from many
licorice formulas. This is called deglycyrrhizinated licorice (DGL).
What is the history behind it?
Licorice extract has been used in traditional Chinese medicine
for centuries. The Chinese used it as a mild laxative and to help
regulate the heartbeat in those with heart problems. Traditional
Chinese herbalists often prescribe licorice with the intent of helping
other herbs to work better together and promoting absorption of herbs.
It was also used for medicinal purposes in ancient Egypt, Greece, and
Rome.
What is the evidence?
Some research suggests that licorice can promote healing of
peptic ulcers. However, most of the evidence is from older studies,
smaller case series, and laboratory studies. Licorice is less effective
than conventional prescriptions and over-the-counter medications for
ulcers.
Laboratory studies have identified several substances in
licorice that may help prevent DNA mutations, inhibit tumor formation,
or even kill cancer cells. For example, Licochalcone-A, glabridin, and
licocoumarone have been tested using cancer cells growing in laboratory
dishes, and preliminary studies indicate that these chemicals can stop
the growth of or even kill breast cancer, prostate cancer, and leukemia
cells. In studies with mice, glycyrrhizin and glycyrrhizic acid reduced
formation of skin, colon, liver, uterine, and breast cancers.
Although results of animal studies suggest some chemicals from
licorice might be useful in preventing or treating some forms of
cancer, no human clinical trials of licorice supplements or substances
from licorice have been reported. Licorice is an ingredient in PC-SPES,
an herbal product for prostate cancer treatment, and although there
have been several clinical trials of PC-SPES (see the document
PC-SPES), they do not address whether licorice contributed to its
benefits.
Glycyrrhizin may be useful as a treatment for chronic
hepatitis, and a Japanese study found that patients with chronic
hepatitis C who took this supplement had lower risk of liver cancer.
However, this study asked patients to remember and report whether they
had used the supplement in the past. This kind of study is considered
less reliable than a clinical trial that randomly assigns patients to
various treatments and follows the patients over time.
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 provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not 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 written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
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.
Regular consumption of licorice has been shown to cause
headaches, lethargy, water retention, high blood pressure, and muscle
weakness. In extremely large amounts, it can cause paralysis and heart
failure. People with high blood pressure, irregular heart beat, or
cardiovascular, kidney, or liver diseases should avoid licorice unless
given under a doctor’s supervision. Use of DGL, or
deglycyrrhizinated licorice, helps to avoid the risk of more serious
side effects.
Studies in laboratory animals have suggested that licorice may
cause birth defects. Women who are pregnant should not use licorice.
Most herbalists also recommend that women who are breast-feeding avoid
this supplement.
In addition, the potential interactions between licorice and
other drugs and herbs should be considered. For example, licorice can
cause problems for patients taking heart medicines, steroids,
diuretics, or insulin. Blood-thinning medications, and hormone therapy
can interact with licorice and even DGL. Some of these combinations may
be dangerous. Always tell your doctor and pharmacist about any herbs
you are taking. 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-ACS-2345).
References
Arase Y, Ikeda K, Murashima N, Chayama K, Tsubota A, Koida I,
Suzuki Y, Saitoh S, Kobayashi M, Kumada H. The long term efficacy of
glycyrrhizin in chronic hepatitis C patients. Cancer.
1997;79:1494-1500.
Blumenthal M, ed. The
Complete German Commission E Monographs: Therapeutic Guide to Herbal
Medicines. Austin, TX: American Botanical Council; 1998.
Davis EA, Morris DJ. Medicinal uses of licorice through the
millennia: good and plenty of it. Mol
Cell Endocrinol. 1991;78:1-6.
Edwards CR. Lessons from licorice. N Engl J Med.
1991;325:1242-1243.
Fu Y, Hsieh TC, Guo J, Kunicki J, Lee MY. Darzynkiewicz Z, Wu
JM. Licochalcone-A, a novel flavonoid isolated from licorice root
(Glycyrrhiza glabra), causes G2 and late-G1 arrests in
androgen-independent PC-3 prostate cancer cells. Biochem Biophys Res Commun.
2004;322:263-270.
Izzo AA, Di Carlo G, Borrelli F, Ernst E. Cardiovascular
pharmacotherapy and herbal medicines: the risk of drug interaction. Int J Cardiol.
2005;98:1-14.
Licorice. Guide to medicinal and aromatic plants. Purdue
University Web site.
http://www.hort.purdue.edu/newcrop/med-aro/factsheets/LICORICE.html.
Updated December 6, 1997. Accessed June 6, 2008.
Licorice. Memorial Sloan-Kettering Cancer Center Web site.
http://www.mskcc.org/mskcc/html/69281.cfm. Updated August 14, 2007.
Accessed June 6, 2008.
Miyake K, Tango T, Ota Y, Mitamura K, Yoshiba M, Kako M,
Hayashi S, Ikeda Y, Hayashida N, Iwabuchi S, Sato Y, Tomi T, Funaki N,
Hashimoto N, Umeda T, Miyazaki J, Tanaka K, Endo Y, Suzuki H. Efficacy
of Stronger Neo-Minophagen C compared between two doses administered
three times a week on patients with chronic viral hepatitis. J Gastroenterol Hepatol.
2002;17:1198-1204.
Niwa K, Lian Z, Onogi K, Yun W, Tang L, Mori H, Tamaya T.
Preventive effects of glycyrrhizin on estrogen-related endometrial
carcinogenesis in mice. Oncol
Rep. 2007;17:617-622
Sigurjonsdottir HA, Manhem K, Axelson M, Wallerstedt S.
Subjects with essential hypertension are more sensitive to the
inhibition of 11 beta-HSD by liquorice. J Hum Hypertens.
2003;17:125-131.
Suzuki F, Schmitt DA, Utsunomiya T, Pollard RB. Stimulation of
host resistance against tumors by glycyrrhizin, an active component of
licorice roots. In Vivo.
1992;6:589-596.
Tamir S, Eizenberg M, Somjen D, Stern N, Shelach R, Kaye A,
Vaya J. Estrogenic and antiproliferative properties of glabridin from
licorice in human breast cancer cells. Cancer Res.
2000;60:5704-5709.
Wang ZY, Nixon DW. Licorice and cancer. Nutr Cancer.
2001;39:1-11.
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: 11/01/2008
Last Revised: 11/01/2008
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