Used medicinally for thousands of years, licorice root contains hundreds of bioactive compounds now being studied for effects involving the liver, digestive tract and oral health, although its glycyrrhizin content can also cause potentially serious side effects.
By yourNEWS Media Newsroom.
Licorice root has occupied a place in traditional medicine for thousands of years, and modern researchers are continuing to examine whether compounds in the ancient herb can help protect the liver, soothe the digestive tract and promote healing in the mouth.
Known scientifically as Glycyrrhiza glabra, licorice has a documented history reaching back at least 3,000 years. Substantial quantities of the root were discovered in the tomb of Egyptian King Tutankhamun, while ancient Egyptians prepared a sweet licorice beverage known as mai sus for ceremonies honoring the spirits of pharaohs.
The army of Alexander the Great also reportedly used licorice root to ease thirst.
Nazim Mamedov, a former assistant professor of ethnobotany and ethnopharmacology at the University of Massachusetts Amherst, has said the herb appears in the Epic of Gilgamesh, regarded as the world’s oldest surviving epic poem. Hippocrates also considered licorice useful for dehydration and ulcers.
The root’s distinctive sweetness is another feature that has contributed to its long history of use. Licorice can be approximately 50 times sweeter than ordinary sugar.
The historical record is now intersecting with laboratory and clinical research as scientists investigate traditional herbal approaches to conditions involving the liver, gastrointestinal tract and other organ systems. Research into medicinal plants and liver health has also contributed to renewed interest in compounds found in licorice.
Licorice Across Chinese Medicine and Ayurveda
Licorice has maintained an especially prominent role in traditional Chinese medicine, where it is known as gan cao.
Rather than being used solely for one organ system, it has traditionally been added to numerous herbal preparations as a harmonizing ingredient. Its sweetness helps mask the stronger flavors of other herbs, while traditional practitioners believe it can moderate some of their harsh effects and help guide a formula throughout the body’s meridian system.
Traditional Chinese uses include replenishing chi, clearing heat, removing toxins, moistening the lungs and easing cough, spasms and pain.
Licorice has remained widely used in Chinese herbal practice for more than three millennia, in part because practitioners historically believed it could improve the tolerability and absorption of other ingredients.
Ayurveda has its own extensive history with the herb.
Known as Yashtimadhu, meaning “sweet stick,” licorice has traditionally been regarded as a rejuvenating tonic. Practitioners have used it for complaints involving the throat, stomach and respiratory system, as well as ulcers and general support for strength and well-being.
Historical Western herbal practitioners similarly used licorice for coughs, chest complaints and irritation of mucous membranes lining the respiratory, urinary and digestive systems.
The Eclectic medical tradition employed it for conditions including chronic gastritis and peptic ulcers, as well as adrenal disorders.
Mamedov has identified cough, bronchial asthma, Addison’s disease, cold sores, mouth sores, stomach discomfort, ulcers, eczema and the common cold among licorice’s most common traditional applications.
Licorice has also been classified in some herbal traditions as an adaptogen, a term used for substances believed to help the body respond to physical or environmental stress.
Chewing licorice sticks has additionally been practiced as a traditional method of supporting teeth and gums.
Hundreds of Compounds Identified in Licorice
Modern chemical analysis has identified approximately 400 bioactive substances in licorice, including about 300 flavonoids.
Among the best known is glycyrrhizin, the compound responsible for much of the herb’s intense sweetness and many of its biological effects.
After licorice is consumed, intestinal bacteria convert glycyrrhizin into glycyrrhetinic acid. Researchers have associated that metabolite with anti-inflammatory, antiviral, antioxidant and tissue-protective activity.
Glycyrrhizin is also responsible for many of licorice’s most important safety concerns.
Its effects can interfere with processes controlling sodium, potassium and water balance. Excessive intake can cause the body to retain sodium and fluid while losing potassium, potentially increasing blood pressure and placing additional strain on the cardiovascular system.
Those effects led to the development of deglycyrrhizinated licorice, commonly called DGL.
DGL has most of its glycyrrhizin removed, substantially reducing the particular risks of elevated blood pressure, fluid retention and potassium depletion associated with conventional licorice preparations.
Whole licorice root has also attracted attention because glycyrrhizin has structural similarities to cortisol, a hormone produced by the adrenal cortex.
Some naturopathic and herbal practitioners have consequently used whole licorice root for what they describe as adrenal weakness or burnout and in connection with Addison’s disease, a serious medical condition involving inadequate production of adrenal hormones.
Research into licorice’s effects on the liver has separately focused on glycyrrhizin’s influence on free-radical production and lipid peroxidation.
Liver Research Examines Glycyrrhizin
Some of the more extensive research involving licorice has examined liver inflammation and viral hepatitis.
In a randomized controlled trial involving approximately 1,400 patients with primary liver disease, licorice treatment was associated with reduced liver inflammation.
Laboratory research involving hepatitis C-infected liver cells also found reductions in viral activity, with relatively small concentrations reportedly reducing activity by roughly half.
Studies have additionally examined glycyrrhizin in combination with interferon alpha, a treatment historically used against hepatitis C. Researchers reported synergistic activity when the two were combined, along with reductions in alanine aminotransferase, or ALT, among European patients with chronic hepatitis C.
Such findings concern specific compounds, doses and patient populations and do not establish that ordinary licorice products can treat hepatitis or other liver diseases without medical supervision.
Glycyrrhetinic acid has also been studied in connection with liver injury associated with toxins, including acetaminophen and alcohol.
Digestive Research Focuses on Ulcers and Stomach Protection
Licorice’s traditional reputation as a digestive remedy has generated considerable modern research.
Researchers have examined its possible ability to stimulate production of protective mucus within the stomach, reduce acid and pepsin activity, increase blood flow to injured stomach tissue and decrease local inflammation.
Licorice compounds have also demonstrated activity against Helicobacter pylori, the bacterium associated with many peptic ulcers.
Clinical trials have evaluated licorice-derived preparations for preventing or treating gastric ulcers, including comparisons with treatments such as cimetidine.
DGL has become particularly prominent in digestive-health applications because it removes most of the glycyrrhizin responsible for licorice’s blood-pressure and electrolyte effects while retaining other constituents associated with mucosal protection.
Michael T. Murray, a naturopathic physician, author and researcher, has described DGL as his preferred form when using licorice for peptic ulcers.
“I have treated many cases of peptic ulcers over the years with 100 percent success using DGL,” Murray said. “It is extremely safe with no side effects or contraindications.”
That statement reflects Murray’s clinical experience and should not be interpreted as proof that DGL will produce the same outcome for every patient.
DGL was once viewed as comparatively inactive after removal of glycyrrhizic acid, but subsequent research suggested other components could promote healing of the stomach lining.
Chewable preparations are commonly emphasized for peptic-ulcer applications because mixing DGL with saliva is thought to promote the release of substances involved in protecting and repairing gastrointestinal tissues.
For that reason, some research and herbal guidance have favored chewable DGL tablets over capsules.
Studies Examine Mouth Sores and Oral Inflammation
Licorice has also been investigated for several painful conditions affecting the mouth.
A systematic review found reductions in pain associated with licorice treatment across three oral conditions: canker sores, oral lichen planus and radiation-induced oral mucositis.
Another review concentrating specifically on canker sores reported improvements in pain, ulcer size and healing time.
Research comparing traditional herbal mouthwashes has also found licorice and triphala preparations capable of reducing oral bacteria.
Those findings correspond with the herb’s longstanding traditional use for mouth irritation and with the practice of chewing licorice sticks for oral care.
Regular Licorice and DGL Have Different Safety Profiles
The distinction between ordinary licorice and DGL is important because medicinal doses of glycyrrhizin-containing licorice can produce significant physiological effects.
For otherwise healthy people, occasional exposure through food generally poses considerably less concern than high-dose or prolonged medicinal use.
Heavy or extended consumption can increase blood pressure, lower potassium and produce fluid retention. Severe electrolyte abnormalities may contribute to abnormal heart rhythms and other cardiovascular complications.
Licorice can also interact with medications, including diuretics, corticosteroids, digoxin and some drugs used to control blood pressure.
Glycyrrhizin may affect the metabolism of steroid hormones as well. Research has described possible increases in concentrations of progesterone and other steroids, with reported consequences including menstrual disruption, reduced libido and hormonal abnormalities.
Because the biological effects depend heavily on glycyrrhizin content, preparations that look similar on a store shelf may have substantially different safety considerations.
Doses Depend on Preparation and Intended Use
Murray has written that medicinal dosing should take glycyrrhetinic acid exposure into consideration, with the objective of reaching potentially useful levels without increasing the likelihood of adverse effects.
Commonly described doses taken three times daily include 1 to 2 grams of powdered licorice root, 2 to 4 milliliters of a 1-to-1 liquid extract, or 250 to 500 milligrams of a 4-to-1 dry extract.
Those amounts are not universally appropriate and should not be interpreted as individualized medical recommendations.
Peptic-ulcer applications using DGL are handled differently because the preparation is generally chewed rather than swallowed intact.
The importance of dose, duration and formulation makes licorice different from many foods that can generally be consumed without close attention to their pharmacological activity.
Whole licorice contains compounds capable of affecting blood pressure, electrolyte balance, hormone metabolism and medication response. DGL removes much of the component responsible for those effects but is generally used for a narrower range of digestive applications.
For people with cardiovascular disease, kidney problems, electrolyte abnormalities or other medical conditions — as well as those using prescription medications — medicinal licorice warrants particular caution.
The herb’s history stretches from ancient Egypt and Mesopotamia through Chinese medicine, Ayurveda and Western herbal traditions. Modern research has identified biological mechanisms that may help explain some of those traditional uses, particularly in the digestive tract and liver.
At the same time, the same chemistry that gives licorice many of its potential therapeutic effects can make high-dose or prolonged use unsafe.
People considering medicinal licorice, particularly glycyrrhizin-containing products, should therefore discuss its use with a qualified healthcare professional who can account for medications, health conditions, dose and duration.
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