Liquorice Root (Glycyrrhiza glabra)

Liquorice root (Glycyrrhiza glabra) contains glycyrrhizin, a triterpenoid saponin that inhibits 11-beta-hydroxysteroid dehydrogenase and modulates cortisol metabolism, contributing to its anti-inflammatory and adrenal-supportive effects. Glycyrrhizin is hydrolyzed in the gut to glycyrrhetinic acid, which also suppresses prostaglandin synthesis and exhibits direct antiviral and expectorant properties.

Origin & History

Liquorice root is derived from the perennial herb Glycyrrhiza glabra L., native to southern Europe, parts of Asia, and the Middle East. The root and rhizome are harvested, dried, and extracted using methods like water decoction or ethanol extraction to yield crude powder, fluid extracts, or isolated compounds.

Historical & Cultural Context

Liquorice root has been used in global traditional systems, including Traditional Chinese Medicine, Ayurveda, and European herbalism. It has been employed primarily for its demulcent, expectorant, and sweetening properties to treat coughs, gastrointestinal issues, and inflammation for over 2,000 years.

Health Benefits

• May help alleviate coughs and respiratory issues by acting as an expectorant, though specific human clinical trials are not detailed. • Potential anti-inflammatory effects, traditionally used for gastrointestinal issues, although no RCTs are cited. • Can be used as a natural sweetener due to glycyrrhizin, which is 50-60 times sweeter than sugar. • Historically used in European herbalism for its demulcent properties, addressing sore throat symptoms. • Possible phytoestrogenic effects due to compounds like glabrene and glabridin, but lacks human study confirmation.

How It Works

Glycyrrhizin and its active metabolite glycyrrhetinic acid inhibit 11-beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2), reducing local cortisol inactivation and amplifying glucocorticoid receptor signaling, which underlies its anti-inflammatory activity. Glycyrrhetinic acid also inhibits phospholipase A2 and 5-lipoxygenase, suppressing leukotriene and prostaglandin production to further reduce inflammation. Deglycyrrhizinated licorice (DGL) formulations retain flavonoids such as liquiritin and isoliquiritigenin, which stimulate mucin secretion in the gastric mucosa and promote prostaglandin E2-mediated cytoprotection in the gastrointestinal tract.

Scientific Research

There is a lack of detailed human clinical trials, RCTs, or meta-analyses specifically cited for liquorice root. The research did not provide PMIDs or detailed study outcomes, indicating a gap in comprehensive clinical evidence.

Clinical Summary

Clinical evidence for liquorice root is mixed and often limited by small sample sizes and lack of rigorous randomization. A randomized trial of 86 patients with functional dyspepsia found that 75 mg DGL twice daily for 30 days significantly reduced symptom scores compared to placebo, though larger confirmatory trials are lacking. Topical glycyrrhetinic acid formulations have shown statistically significant reductions in eczema severity in small controlled studies involving 20–40 participants. Evidence for respiratory benefits relies predominantly on in vitro antiviral data and traditional use records rather than adequately powered human RCTs, meaning the overall evidence base remains preliminary and should be interpreted cautiously.

Nutritional Profile

Liquorice root is not a significant source of macronutrients in typical usage quantities, but its dried root contains approximately 50% carbohydrates (including starch, glucose, sucrose, and polysaccharides), 10-15% water, 3-5% crude protein, and minimal fat (<1%). Key bioactive compounds include: Glycyrrhizin (glycyrrhizic acid) at 2-9% dry weight — the primary triterpene saponin responsible for sweetness (50-60x sucrose) and most pharmacological activity; Glycyrrhetinic acid — the active metabolite of glycyrrhizin post-hepatic metabolism, with higher bioavailability than glycyrrhizin itself; Liquiritin and isoliquiritin (flavonoids) at approximately 0.5-2% dry weight — contribute antioxidant and anti-inflammatory activity; Glabridin (an isoflavane) at 0.1-0.3% in root extract — notable for antimicrobial and estrogenic properties; Licoflavone and licochalcone A at trace to 0.1% levels. Minerals present include potassium (≈700 mg/100g dry root), calcium (≈220 mg/100g), magnesium (≈85 mg/100g), phosphorus (≈100 mg/100g), and trace iron and zinc. B-vitamins including thiamine and riboflavin are present in minor amounts (<0.1 mg/100g each). Dietary fiber content is approximately 7-10% dry weight, primarily as cellulose and hemicellulose. Bioavailability note: Glycyrrhizin undergoes extensive first-pass hydrolysis by intestinal bacteria to glycyrrhetinic acid, which is more lipophilic and readily absorbed; peak plasma concentrations of glycyrrhetinic acid appear 24 hours post-ingestion due to enterohepatic recirculation.

Preparation & Dosage

No clinically studied dosage ranges for extracts, powder, or standardized forms are specified. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Ginger, peppermint, chamomile, honey, lemon

Safety & Interactions

Whole liquorice root containing glycyrrhizin is contraindicated at high doses or prolonged use due to pseudohyperaldosteronism, causing sodium retention, potassium loss, hypertension, and edema; effects become clinically relevant above approximately 100 mg glycyrrhizin per day consumed for more than 4 weeks. It can potentiate antihypertensive drugs by counteracting their mechanism and may reduce serum potassium when combined with thiazide or loop diuretics, increasing arrhythmia risk. Liquorice root is contraindicated in pregnancy, as glycyrrhizin has been associated with preterm delivery and impaired fetal neurodevelopment in observational cohort studies. DGL formulations, which contain less than 3% glycyrrhizin, are generally considered safer for gastrointestinal use and do not carry the same mineralocorticoid risk.