Licorice

Glycyrrhiza glabra L.

G. uralensis Fisch. ex DC. and G. inflata Batalin (Chinese licorice),
G. echinata L. (East European licorice), and other species of Glycyrrhiza

Family: Fabaceae

Introduction

Licorice is native to the Mediterranean, central-to-southern Russia, and Asia Minor to Iran, and it is now widely cultivated throughout Europe, the Middle East, and Asia.¹ It is a perennial with aggressive laterally spreading roots and loose spikes of pale blue to violet pea flowers in summer.² The roots or stolons (underground horizontal stems) are the most commonly used plant parts and can be harvested after 3 to 4 years of growth.¹

History And Cultural Significance

Dioscorides, a first-century Greek physician, coined a name that was later developed into the genus name Glycyrrhiza, which is derived from a combination of the Greek words, glukos (sweet) and riza (root).¹ One of the main constituents of the root is glycyrrhizin (also known as glycyrrhizic acid or glycyrrhizinic acid), which is about 50 times sweeter than sucrose (common sugar).¹ The Roman name, gliquiricia, which became liquiritia, evolved over the years into licorice.³

Ancient Arabs used licorice to treat coughs and to relieve constipation.¹ Theophrastus, an ancient Greek physician and botanist (circa 371 – 286 BCE), documented the use of licorice to assist with coughs and asthma. Since 25 CE, the Chinese have used the herb extensively to relieve and prevent cough and as an expectorant, as well as an adjuvant in many herbal formulas. It also relieves spasms of the smooth (involuntary) muscles and exhibits a cortisone-like action. Licorice has a long history as a common remedy in Ayurvedic medicine for its expectorant, anti-inflammatory, and laxative properties. The German Commission E approved licorice root for inflammations of the upper respiratory tract and stomach ulcers.¹

Until around 1000 CE, licorice was collected mainly in the wild, which is still a common practice in China.¹ Cultivation was recorded in Bologna, Italy, in the 13th century, in Bavaria in the 16th century, and in Northern England by the end of the 16th century.⁴

Most of the natural licorice imported to the United States today is used to flavor tobacco products.¹ Licorice root extract is used in cough drops, syrups, laxatives, and nicotine lozenges, and it is added to foods to sweeten them. The root is added to teas and can be purchased dried, sliced, or powdered.³ The root is also sold in capsules, tablets, tinctures, and other dietary supplements for traditional uses or as a flavoring.⁵ Licorice preparations are added to candy, cakes, ice cream, and packaged desserts, but most of the candy sold in the United States today as licorice is flavored with a synthetic licorice or flavorings made from anise (Pimpinella anisum L., Apiaceae).³

Modern Research

Licorice is one of the most extensively researched medicinal and food plants.¹ Studies on licorice have demonstrated positive effects for treatment of various types of ulcers and chemoprevention.⁶ Other studies indicate the following: (1) dietary consumption of licorice root extract may help to lower cholesterol and act as an antioxidant,^6,7 (2) compounds in licorice inhibit serotonin re-uptake and may be useful in the treatment of mild to moderate depression in women,⁸ and (3) licorice may help reduce body fat mass.⁹ One study suggests that topical application of licorice extract may be effective in treating the itching and inflammation associated with dermatitis.¹⁰

Persons with cholestatic liver disorders, liver cirrhosis, hypertension, hypokalemia (low levels of potassium in blood), severe kidney insufficiency, and possibly diabetes (unconfirmed contraindication) should consult a healthcare provider before using licorice.⁶ Licorice is not recommended during pregnancy, as heavy exposure to glycyrrhizin may double the risk of birth before 38 weeks.¹¹

No adverse effects have been associated with licorice root preparations when used appropriately. Prolonged use (longer than 6 weeks) and higher doses (generally greater than 50 g per day) may lead to sodium retention, water retention, and potassium loss, all of which may be accompanied by hypertension, edema (swelling), hypokalemia, and in rare cases, myoglobinuria (excretion of the muscle’s oxygen-transporting protein, myoglobin, in the urine).⁶ Side effects are less likely with aqueous licorice root extract than with isolated glycyrrhizin due to the lower intestinal absorption when consumed as part of the total extract.¹²

In 2 separate cases, pulmonary edema and life-threatening ventricular tachycardia (rapid heart beat) due to hypokalemia occurred as a result of overdoses of black licorice-flavored candy. Dietary supplements are available that contain licorice extracts with the glycyrrhizin removed. This eliminates some of the potential adverse effects associated with consumption of relatively large amounts of licorice (as noted above).

Licorice may potentiate the side effects of potassium-depleting thiazide diuretics (e.g., chlorothiazide, chlorthalidone, hydrochlorothiazide, and metolazone). With potassium loss, sensitivity to digitalis glycosides (heart medications, e.g., digoxin, lanoxin) increases. Licorice should not be combined with corticoid treatment.⁶

—Gayle Engels

References

1. Blumenthal M, Goldberg A, Brinckmann J, editors. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; Newton, MA: Integrative Medicine Communications; 2000.

2. Bown D. The Herb Society of America New Encyclopedia of Herbs & Their Uses. New York: DK Publishing, Inc.; 2001.

3. Onstad D. Whole Foods Companion. White River Junction, VA: Chelsea Green Publishing Co.; 1996.

4. Foster S, Yue C-X. Herbal Emissaries: Bringing Chinese Herbs to the West. Rochester, VT: Healing Arts Press; 1992.

5. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Foods, Drugs, and Cosmetics. New York: John Wiley and Sons; 1996.

6. Blumenthal M, Hall T, Goldberg A, Kunz T, Dinda K, Brinckmann J, Wollschlaeger B, editors. The ABC Clinical Guide to Herbs. Austin, TX: American Botanical Council; 2003.

7. Fuhrman B, Volkova N, Kaplan M, et al. Antiatherosclerotic effects of licorice extract supplementation on hypercholesterolemic patients: Increased resistance of LDL to atherogenic modifications, reduced plasma lipid levels, and decreased systolic blood pressure. Nutrition. 2002:18;268-273.

8. Ofir R, Tamir S, Khatib S, Vaya J. Inhibition of serotonin re-uptake by licorice constituents. Journal of Molecular Neuroscience. 2003:20(2);135-140.

9. Armanini D, De Palo CB, Matterello MJ, et al. Effect of licorice on the reduction of body fat mass in healthy subjects. Journal of Endocrinological Investigation. 2003:26(7);646-650.

10. Saeedi M, Morteza-Semnani K, Ghoreishi M-R. The treatment of atopic dermatitis with licorice gel. Journal of Dermatological Treatment. 2003:14;153-157.

11. Strandberg TD, Javenpaa A-L, Vanhanen H, McKeigue PM. Birth Outcome in relation to licorice consumption during pregnancy. American Journal of Epidemiology. 2001;153(11):1085-1088. Cited by: Blumenthal M, Hall T, Goldberg A, Kunz T, Dinda K, Brinckmann J, Wollschlaeger B, editors. The ABC Clinical Guide to Herbs. Austin, TX: American Botanical Council; 2003.

12. Cantelli-Forti G, Maffei F, Hrelia P, et al. Interaction of licorice on glycyrrhizin pharmacokinetics. Environ Health Perspectives. 1994;102:65-68. Cited by: Blumenthal M, Hall T, Goldberg A, Kunz T, Dinda K, Brinckmann J, Wollschlaeger B, editors. The ABC Clinical Guide to Herbs. Austin, TX: American Botanical Council; 2003.