An ancient remedy finds modern
Licorice is commonly found in the traditional herbal formulations of many cultures. It has been used therapeutically for centuries in both Eastern and Western medicine to treat various conditions. Today, licorice is the most commonly used herb in traditional Chinese medicine, often administered in combination with other herbs.
Ancient documents from the Middle East reveal that licorice was used to treat dry coughs, sore throats, and other respiratory conditions. In traditional Chinese medicine, it proved effective in the treatment of bronchitis, laryngitis, and bronchial asthma, as well as dyspepsia and other digestive problems. Over the centuries licorice has soothed inflammation of the mucous membranes, treated stomach and duodenal ulcers, and eased chronic gastritis.
The useful part of the herb is its root. Licorice is commercially harvested from the roots of Glycyrrhiza glabra, a member of the legume family. The shrub grows to a height of four to five feet throughout the Mediterranean region, the Middle East, and regions of western Asia, northern China, and southern Russia.
The Latin name for licorice, Glycyrrhiza, means sweet root. A major component of the product is the triterpenoid glycyrrhizin, a compound that’s about 50 times sweeter than sugar. Licorice also contains small amounts of volatile terpenoids such as anethole, which provides the pleasant flavor.
Licorice is an approved flavoring agent for gum, candy, soft drinks, ice cream, and baked goods. However, many licorice products actually don’t contain licorice since its flavor can be mimicked by anise. The anethole-containing oil that’s obtained from the seeds of anise smells and tastes just like licorice, and anise oil is a lot cheaper.
Many Protective Factors
Licorice is useful for the treatment of inflamed mucous membranes of the upper respiratory tract and for oral, gastric, and duodenal ulcers. The flavonoids in its root are thought to be responsible for its anti-ulcer activity. The substance licorione protects against stomach ulcers by lowering the acidity of the stomach and inhibiting gastric secretions.
A major constituent of the licorice root is glycyrrhizin, the triterpenoid glycoside, which possesses anti-inflammatory and anti-allergic properties. Glycyrrhizin has also shown to provide protection against the influenza virus. Licorice is also useful for the treatment of coughs and sore throat. It has pronounced expectorant and effective cough-suppressant properties.
Glycyrrhizin-containing preparations (obtained from licorice root extracts) have shown promise in the treatment of HIV-related diseases including AIDS. Glycyrrhizin modulates the cell-mediated immune system. When HIV-positive patients were daily given tablets of glycyrrhizin, their helper T-cell counts increased, helper-to-suppressor T-cell ratios got higher, and liver function improved within 2 months. In a similar study, those receiving the licorice extract had substantially better survival rates after 2 years than the matched control group.
A number of unique flavonoids in licorice provide some useful properties. The chalcones possess anti-tumor properties, as well as being active against gram-positive bacteria. The flavonoid glabridin in licorice is a powerful antioxidant that protects against the oxidation of LDL cholesterol, and hence, reduces the risk of atherosclerosis. The flavonoids also protect against Staphylococcus, Candida, and other microbes.
Reports of Toxicity
While licorice is useful for treating peptic ulcer, the treatment should not exceed four to six weeks because of the known side effects. Excessive use may also produce serious side effects. Large amounts of glycyrrhzin in licorice can cause fluid retention (edema) and high blood pressure due to sodium retention and potassium depletion (hypokalemia). Life-threatening arrhythmia has been reported from hypokalemia after large amounts of licorice were consumed. Patients with cardiovascular or kidney disease should either avoid the root altogether or use it only under the supervision of a physician. It’s also not recommended for persons with diabetes since it can interfere with blood glucose control.
Licorice should also be avoided during pregnancy as it can cause the uterus to contract, possibly sparking premature delivery. It should also be avoided during breast-feeding because of insufficient information regarding its safe usage.
Licorice has been successfully used as a cough suppressant and aid for congestion of the upper respiratory tract. Clinical studies confirm its usefulness for the treatment of gastric and duodenal ulcers. However, large amounts of glycyrrhizin are toxic, so eating it should be discontinued after four to six weeks. Licorice with its glycyrrhizin removed is usually free of adverse effects.
Winston J. Craig is professor of nutrition at Andrews University, Berrien Springs, Michigan.