Chinese licorice: Difference between revisions

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| intro = Chinese licorice (''Glycyrrhiza uralensis'' Fisch.) is a perennial leguminous herb of the north Chinese steppe, the botanical source of gan cao (甘草, literally "sweet herb"), one of the most widely prescribed medicinals in the entire Chinese Materia Medica. Gan cao occupies a role in classical Chinese medicine without parallel in Western pharmacology: it is the defining harmonizer of formulas (调和诸药, tiáo hé zhū yào), an herb added to approximately sixty percent of all classical formulae not primarily for a specific therapeutic action of its own but to moderate the potency of harsh or toxic herbs, unify the divergent properties of a formula's ingredients, and protect the stomach and spleen from irritating constituents. The closely related Mediterranean species ''G. glabra'' (Western licorice) is the historical centroid of Ayurvedic, Unani, and European herbal licorice use; the two species share essentially the same glycyrrhizin-mediated pharmacology and the same pseudohyperaldosteronism safety profile, described in full at [[Western licorice]]. Both species are routinely substituted in commerce without pharmacopoeia distinction.

| taxonomy = ''Glycyrrhiza uralensis'' Fisch. ex DC. belongs to tribe Galegeae, family Fabaceae, one of approximately thirty species in the genus ''Glycyrrhiza''. The genus name derives from the Greek glykys (sweet) and rhiza (root), reflecting the intensely sweet taproot shared across the genus. ''G. uralensis'' is distinguished from ''G. glabra'' (European licorice) by glandular-hairy stems and seed pods, a more compact and shorter flower raceme, and a tendency to form dense rhizome mats in the steppe and semi-arid grasslands it inhabits; these morphological distinctions are unreliable in dried commercial root stock, and commercial substitution of the two species is routine and pharmacopoeially sanctioned under most major pharmacopoeias. ''G. inflata'' (Xinjiang licorice) is a third commercially significant species, particularly sourced in Central Asian markets.

The medicinal parts are the root and rhizome, harvested from plants four years or older; roots from younger plants have lower glycyrrhizin content and are considered suboptimal quality. In TCM practice the dried root is processed in two clinically distinct forms: sheng gan cao (生甘草, raw or unprocessed dried root), used for fire-toxicity conditions and as the universal harmonizing constituent; and zhi gan cao (炙甘草, honey-fried root), prepared by combining sliced dry root with liquid honey (typically 25 g honey per 100 g dry root) and stir-frying over gentle heat until the honey is fully absorbed and the surface is fragrant and golden-brown. TCM processing theory holds that honey-frying shifts the root's properties from the neutral-cooling of the raw form toward a warmer, more tonifying quality particularly suited to heart-calming and spleen-tonifying indications.

| traditional_uses = '''Chinese medicine (primary centroid)'''

''G. uralensis'' has no significant independent tradition in Ayurvedic or Unani medicine; the yashtimadhu (sweet stick) of Ayurveda, the asl-us-sus of Unani medicine, and the glykyrrhiza of the Greco-Roman and medieval European herbal traditions are rooted in ''G. glabra'', the Mediterranean species. ''G. uralensis'' enters Western herbal and Ayurvedic practice primarily through commercial substitution: international licorice root trade routinely mixes or substitutes the two species, as dried root from the two is morphologically indistinguishable in commerce and the pharmacological properties are sufficiently comparable for pharmacopoeial equivalence. The complete traditions of Western herbal, Ayurvedic, Unani, and Greco-Roman licorice practice are documented at [[Western licorice]].

| preparations = Sheng gan cao (生甘草, raw dried root): unprocessed dried sliced root used in TCM decoction for fire-toxicity conditions (throat swellings, carbuncles, heat patterns), lung-dryness cough, and the universal formula-harmonizing role. This is also the standard commercial source material for Western herbal extracts and pharmaceutical-grade glycyrrhizin extraction.

Deglycyrrhizinated licorice (DGL): available in Western clinical herbal practice as a preparation from which glycyrrhizin has been removed, retaining demulcent and mucosal-protective activity without the pseudohyperaldosteronism risk. Western market DGL preparations are predominantly derived from ''G. glabra'' material; ''G. uralensis''-sourced DGL exists but is less commonly available in Western markets. The full DGL discussion, including clinical evidence, dose, and chronic-use appropriateness, is at [[Western licorice]].

| pharmacology = '''Principal active constituents'''

Glycyrrhetic acid (enoxolone): the free aglycone of glycyrrhizin; the basis of the pharmaceutical derivative carbenoxolone, the synthetic peptic ulcer compound developed in Europe in the 1960s to 1970s, documented at [[Western licorice]].

| indications = '''TCM indications (primary)'''

Western clinical research on licorice does not systematically distinguish ''G. uralensis'' from ''G. glabra''; commercial preparations are often from mixed or unspecified species. The evidence base for peptic ulcer and mucosal protection (deglycyrrhizinated licorice preparations), chronic hepatitis (intravenous Stronger Neo-Minophagen C glycyrrhizin compound in Japanese clinical practice), respiratory catarrh (Commission E approved indication), and adrenal-supportive use is described in full at [[Western licorice]].

| dosing = TCM decoction dose: 2 to 12 g dried root per day (raw or honey-fried) in multi-herb decoction. Harmonizing doses, which account for the majority of gan cao prescriptions, are typically 2 to 6 g per day; doses in which gan cao is the principal therapeutic herb (as in Gan Cao Tang) may reach 9 to 12 g per day. Single-herb throat formula (Gan Cao Tang): 4 to 9 g.<ref name="bensky2004"/>

Glycyrrhizin intake limit: 100 mg glycyrrhizin per day maximum for chronic use per the European Union Scientific Committee on Food opinion SCF/CS/ADD/EDUL/225 Final (2003), the same guidance applicable to both ''G. uralensis'' and ''G. glabra''.

| pharmacokinetics = Glycyrrhizin is poorly absorbed intact from the gastrointestinal tract; rate-limiting absorption involves bacterial beta-glucuronidase hydrolysis in the large intestine, producing 18-beta-glycyrrhetinic acid with a lag of two to four hours between oral ingestion and rising plasma 18β-GA levels. Individual variation in gut microbiome composition generates substantial inter-individual variability in 18β-GA plasma exposure at equivalent oral glycyrrhizin doses, which partly explains the observed case-to-case variability in pseudohyperaldosteronism susceptibility.

The full pharmacokinetic discussion, including DGL pharmacokinetics and the plasma-level considerations underlying the pseudohyperaldosteronism dose-response, is at [[Western licorice]].

| interactions = The interaction profile of ''G. uralensis'' is identical to that of ''G. glabra''; the shared glycyrrhizin content and shared 11-beta-HSD2 inhibition mechanism produce the same clinically relevant pharmacodynamic interactions regardless of species. Full interaction details are at [[Western licorice]]; the following is a clinical summary.

DGL preparations: negligible pharmacodynamic interaction risk from the glycyrrhizin-mediated pathway; DGL is the preparation of choice for any chronic use requiring avoidance of these interactions.

| interactionsummary = Antihypertensives (antagonism of blood pressure control), potassium-depleting agents including loop and thiazide diuretics and corticosteroids (additive hypokalemia), cardiac glycosides including digoxin (hypokalemia-mediated toxicity potentiation), exogenous corticosteroids (amplification of mineralocorticoid effects). Full DDI discussion at [[Western licorice]]. DGL preparations avoid these interactions.

| safety = The pseudohyperaldosteronism safety profile of ''G. uralensis'' is identical to that of ''G. glabra'': the same 18-beta-glycyrrhetinic-acid-mediated 11-beta-HSD2 inhibition, the same dose-dependent sodium retention, potassium depletion, hypertension, and edema, and the same case-report and regulatory literature. The full mechanism, dose-response, Walker 1994, van Uum 2005, and EU SCF 2003 guidance are documented at [[Western licorice]]. The 100 mg/day glycyrrhizin chronic-use limit applies to whole-licorice preparations of either species.

Contraindications: hypertension, hypokalemia, cardiac arrhythmia, hepatic cirrhosis, renal insufficiency, concurrent use of potassium-depleting agents or cardiac glycosides, and pregnancy at high doses.

| monitoring = Whole-licorice use (any form of ''G. uralensis'' root or extract containing significant glycyrrhizin) for more than four weeks: obtain baseline blood pressure and serum potassium before initiating; recheck monthly during ongoing use. Discontinue and reassess if systolic blood pressure rises more than 10 to 15 mmHg from baseline, serum potassium falls below 3.5 mmol/L, or peripheral edema develops.

DGL preparations: no monitoring required beyond routine clinical follow-up appropriate to the underlying condition being managed.

| counseling = The pseudohyperaldosteronism risk that applies to Western licorice (''G. glabra'') applies equally to Chinese licorice (''G. uralensis'') and to any TCM formula containing gan cao. A patient told by a conventional physician to avoid licorice for blood pressure or potassium reasons should apply that restriction to gan cao in TCM decoctions and patent medicines. The two species are pharmacologically interchangeable with respect to this risk; a patient's conventional prescriber may not know that a TCM formula contains licorice under the name "gan cao" and will benefit from the information.

The guó lǎo (国老, Elder Statesman) characterization of gan cao is a useful explanatory frame for patients: the herb is not added to a formula to fix one thing but to make the entire formula work more safely and effectively together. Patients who ask why their TCM formula contains licorice even though they are not being treated for a licorice-specific condition can be offered this framing as an accurate and culturally grounded explanation.

| history = Gan cao's written history in Chinese medicine extends to the earliest stratum of the Chinese herbal record. The Shennong Ben Cao Jing (first to second century CE) placed it among the 120 upper herbs, the highest-quality classification available in the text's tripartite system, signaling that its safety and tonic utility were already well established by the Han dynasty period (206 BCE to 220 CE) when the text was compiled.{{citation needed}}<!-- Same candidate as traditional_uses above: Yang SZ 1998 Blue Poppy Press translation. -->

Contemporary ''G. uralensis'' populations are subject to conservation pressure from commercial wild harvesting in Inner Mongolia, Gansu, and Xinjiang; overharvesting has substantially reduced wild stands over the past several decades, driving the industry toward cultivated supply. ''Glycyrrhiza'' species are subject to trade-monitoring frameworks requiring country-of-origin export documentation to verify sustainable sourcing.{{citation needed}}<!-- Candidate: CITES (Convention on International Trade in Endangered Species) species database at cites.org; check current Appendix listing and any annotation for ''Glycyrrhiza'' spp. Also: Zhao ZL et al, Journal of Ethnopharmacology 2015 or similar, on ''Glycyrrhiza uralensis'' wild resource decline in China. Topic: CITES listing status (if any) for ''Glycyrrhiza'' species; conservation status of wild ''G. uralensis'' in Inner Mongolia and Xinjiang. Verify at publish before confirming the CITES Appendix claim specifically. --> ''G. uralensis'' is listed in the Pharmacopoeia of the People's Republic of China as an official medicinal herb under the monograph Gan Cao (甘草), and the pharmacopoeia specification includes a minimum glycyrrhizin content standard as a quality criterion, shaping commercial cultivation toward higher-yielding varieties.<ref name="chinpharmacopoeia2020"/>

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