Licorice is the common name for plants of the Glycyrrhiza genus. There are more than 30 species in the Glycyrrhiza genus, but the two most widespread are G. glabra and G. uralensis. Glycyrrhiza glabra has been identified primarily throughout Asia and Europe. Glycyrrhiza uralensis, on the other hand, is best known in Asia, but it is grown throughout Asia, Europe, and North America.^[24][12]

The word “glycyrrhiza” is derived from the Greek words “glycos” (sweet) and “rhiza” (root). Since the oil responsible for the characteristic licorice flavor also has some bioactive components, it is often considered to be a functional food.^[25][12] As a flavoring agent, it is generally recognized as safe (GRAS) for consumption. However, US regulations restrict the maximum glycyrrhizin content in food products to less than 0.1% for baked goods, beverages, seasonings, and as a flavor enhancer, while confectionaries like gum (1.1%), soft candies (3.1%), and hard candies (16.0%) can contain more.

Glycyrrhizin is the component of licorice frequently cited as being responsible for its effects. However, licorice also contains other bioactive compounds including flavonoids, coumarins, and polyphenols like glabridin, quercetin, liquiritigenin and licochalcone.^{[12][26][27][28][29]}

Licorice may aid digestive health through reductions in ulcerations, pain, and inflammation along the digestive tract, which may explain why it is considered to improve symptoms of functional dyspepsia (indigestion) and ulcerative colitis.^{[30][31][32][33]} Similarly, licorice has shown some evidence of relieving the symptoms of postoperative sore throat, rheumatoid arthritis, and atopic dermatitis by suppressing T-cell activity and reducing inflammation (See this FAQ for details.)^{[34][35][36][37][38][39][40][41]}

It is also possible that licorice might prevent tumor growth, protect cells from chemotherapy damage, benefit some cardiovascular measures, and aid in neurological conditions like dementia and epilepsy.^{[42][43][44][45][46][47][48][49][50][51][52]} These findings are promising, but they generally still require further human-based clinical evidence before they can be considered conclusive.

Licorice intoxication or overdose is possible and has been associated with death and rhabdomyolysis (muscle breakdown due to low potassium) in case studies.^[53][10][11] In one small study, 3 of 4 people who consumed 200 grams of licorice in under an hour reported feelings of nausea and fatigue which correlated with serum glycyrrhizin levels.^[53]

The glycyrrhizin component of licorice in particular may raise blood pressure in individuals with hypertension.^[4][54][55] However, supplements with reduced (or undetectable) glycyrrhizin content may not be associated with the same adverse effects.^[56]

High doses of licorice (>500 mg of glycyrrhizin) are known to increase cortisol levels, decrease testosterone, and alter estrogen receptor activity.^{[57][58][3][5][6][7][8][59][60][61][62][63]} Some of the hormonal effects of licorice (including increases in parathyroid hormone and decreases in DHEA) may be sex dependent.^[64][65] Though licorice shows some promise for body fat reduction, these results are still conflicting, and it is possible that weight can increase through water retention.^{[66][4][67][68]}

Glycyrrhizin (and its other forms, glycyrrhetinic and glycyrrhizic acid) is one of the more notable components of licorice, likely due to its high content and bioavailability.^{[69][70][71][72]} One mechanism of glycyrrhizin seems to be its ability to inhibit enzymes, particularly along hormonal pathways. In clinical studies, these enzymatic inhibitions may produce effects such as increased cortisol and reduced testosterone.^{[57][58][3][9][73][74][60]} Preclinical evidence suggests that the enzymatic inhibition by glycyrrhizin might also improve insulin sensitivity (via increased lipoprotein lipase activity), increase lipolysis (via hormone-sensitive lipase activation), and enhance the antiproliferative effects of corticosteroids.^{[75][76][77][78][79][80]} Glycyrrhizin also might provide cardioprotection and relief of stomach cramps.^{[81][82][83][84][85][86]}

Flavonoid groupings, such as glabridin and liquiritigenin, and phenols such as licochalcone A are also found in licorice and may provide other health benefits. Dietary consumption of glabridin may protect LDL cholesterol from oxidation, slowing the progression of atherosclerosis.^[51][52]

In preclinical (animal) studies, glabridin and licochalcone A have shown anti-inflammatory effects through the inhibition of NF-kB activation.^[87][88] Licochalcone A and liquiritigenin both may reduce cytokine release, relax intestinal muscles, and have antitumor properties.^[43][45] Glabridin may also reduce fat storage and/or act as a selective estrogen receptor modulator,^[89][90] and liquiritigenin may reduce the absorption of lipids from the intestines.^[91] However, further research is needed to confirm these findings clinically in humans.