Latin: Glycyrrhiza glabra
Chinese: Gan cao, Zhi gan cao
WHAT IT DOES: Licorice root is sweet in taste and cooling in action. It detoxifies poisons from the blood and liver, and reduces general inflammation and pain. It moistens and heals the lungs and digestive tract.
SAFETY ISSUES: Do not use during pregnancy. Do not use high doses or for a prolonged period of time unless under the care of a qualified health care practitioner. Use cautiously with kidney disease, liver disorders, or if taking thiazide diuretics, cortisone or cardiac glycosides. Licorice prolongs the half-life of cortisone. Read the clinical summary here which explains that the DGL form of licorice is free of these side effects.
• Crude powder: one to three grams three times per day, up to six weeks
• Concentrated 4:1 granules: 150-250 mg. three times per day
Licorice root is one of the most widely used herbs in the world. Every major medical tradition uses it as medicine, usually describing its effects as cooling and tonifying. TCM doctors use it in two forms. Regular licorice root is considered to have an intrinsic harmonizing effect useful for reducing side effects from large combinations of other potent herbs, and for disguising their bitter or acrid flavors. Licorice is said to strengthen the digestion and the hormonal systems and moisten the lungs. TCM doctors also use a honey-fried form to warm digestion when indicated. TAM doctors use licorice root to reduce the pain of sore throat and ulcers, to subdue poisons, and as a major ingredient in cough syrups.
Almost 50 years ago, a scientist by the name of Revers reported that licorice paste reduced abdominal symptoms and caused radiographic evidence of ulcer healing. However, about 20% of patients developed edema, headache and other symptoms due to overdose, leading to a loss of enthusiasm (Schambelan, 1994). This led to the development of DGL (deglycyrrhizinated licorice), a form of licorice that does not contain the agents responsible for the side effects such as electrolyte changes. The de-acidified DGL tablet or capsule form used in Europe and America is therefore devoid of any major side effects, and is effective for healing the intestinal membranes. Because it is chewable, it also is helpful to the esophagus.
Paul Bergner, editor of Medical Herbalism, wrote an article citing recent Japanese and Chinese research highlighting the numerous positive and protective effects licorice root exerts on the liver. Its anti-hepatotoxic effects make it useful in treating chronic hepatitis and possibly cirrhosis. Licorice root contains plant (phyto) estrogens similar to those found in soy (Zava et al., 1998), and has an estrogen-like effect, binding strongly to estrogen receptors. This makes it a good treatment for easing hot flashes, though I would do this only at recommended doses in a formula with other herbs.
Many patients express concerns about using licorice because they have seen negative press coverage of this herb. It is important to understand that these reported concerns are dose-related. Licorice is traditionally used as approximately five percent of a formula, and that is what I usually do with it. If a patient takes the typical six to nine grams of concentrated 4:1 powder per day, this works out to about 1.2-1.8 grams of licorice, well within recommended dosage levels. Personally, I’ve never seen any of the potassium depletion and sodium retention effects described in the literature, and the pharmacologists I’ve consulted with assure me that such effects are rare, and easily reversible simply by stopping use.
The various components of licorice root act in a number of different ways in the test tube, on animals and on humans. It is important to keep in mind that specific results of scientific studies, such as the ones listed below, often relate to particular components of licorice. By examining these various reports you will be able to see the general pattern of cooling and detoxification noted by ancient doctors.
• We now know that the negative effects of licorice overdose, such as blood pressure elevation and fluid retention, are caused primarily by its dose-dependent inhibition of a specific enzyme called 11-HSD. Analysis reveals that this inhibition occurs only after multiple doses of 1.5 grams per day of pure glycyrrhizic acid. Daily doses of 500 mg. or less cause little or no problem (Krahenbuhl et al., 1994, Heilmann et al., 1999, White et al., 1997). In other words, licorice root is safe when used in proper dosage.
• According to several studies, DGL licorice is a very effective ulcer treatment (Morgan et al., 1985, Morgan et al., 1982, Morgan et al., 1987, Russell et al., 1984, Tewari and Wilson, 1973).
• Glycyrrhizin is a major anti-inflammatory compound found in licorice. Its anti-inflammatory action is due in part to the selective inhibition of thrombin (a clotting factor), which results in the removal of blood congestion. Glycyrrhizin was the first such compound to be isolated from a plant (Francischetti et al., 1997)
• Glycyrrhizic acid, a component of licorice roots, was found to inhibit the growth and cytopathology of several unrelated DNA and RNA viruses without affecting cell activity and ability to replicate. Glycyrrhizic acid irreversibly inactivates herpes simplex virus particles (Pompei et al., 1979). For this reason, licorice tincture or paste can be applied directly to lesions.
• In animal studies, licorice root has been shown to enhance liver detoxification of poisons, causing significant increases in liver and urinary excretion of acetaminophen (Moon and Kim, 1997).
• The complex sugars found in licorice root and many other herbs stimulate macrophages (immune cells), but some scientists have expressed concerns that the effects seen in laboratory experiments might have been overstated and due solely or in part to bacterial contamination. However, additional studies determined that macrophage stimulation by licorice root still occurred in plants grown in aseptic conditions (Nose et al., 1998).
• A compound in licorice root called beta-glycyrrhetinic acid has been identified as a potent inhibitor of a certain cascade of inflammatory immune system chemicals (Kroes et al., 1997).
• Licorice extract, along with glutathione and the bioflavonoids, belongs to a class of substances known as “desmutagens.” Scientists Kada and Shimoi categorized these molecules according to their unique ability to bind to toxic chemicals and cancer-causing agents (Shankel et al., 1993).
• DGL can be used as a mouthwash for small mouth ulcers (Das et al., 1989), and may reduce stomach bleeding caused by aspirin (Rees et al., 1979)
• Licorice alcohol extract contains a subclass of polyphenol flavonoids called isoflavones that may reduce the negative effects of LDL cholesterol, and reduce atherosclerotic lesion areas in mice (Fuhrman et al., 1997, Aviram, 1996). This effect was later shown to be similar to that of the bioflavonoid quercetin (Belinky et al., 1998).
• Licorice root has an effect on corticosteroid metabolism that links it to certain receptors in the brain and may eventually lead to applications in studies of mood, neuronal survival, and feedback related to blood pressure. Researchers hope to develop useful means to target specific action sites on the brain (Seckl, 1997).
• A licorice root extract, mostly glycyrrhizin (a saponin extracted from licorice) has been shown pharmacologically to stimulate interferon (Eisenburg, 1992), suggesting that a combination might be more effective than either along. A clinical test on humans showed results for hepatitis C (a reduction in viral load and ALT), but results failed to achieve significance (Abe et al., 1994).