Glycyrrhiza glabra (Licorice)

Glycyrrhiza glabra contains glycyrrhizin and glycyrrhetinic acid, which inhibit 11β-hydroxysteroid dehydrogenase and block inflammatory prostaglandin synthesis. These compounds demonstrate potent antiviral activity against respiratory pathogens and accelerate wound healing through enhanced collagen synthesis.

Origin & History

Glycyrrhiza glabra is a perennial herbaceous plant native to the Mediterranean region and Western Asia, belonging to the Fabaceae (legume) family. The therapeutic component is primarily extracted from the root and rhizome through aqueous, hydroalcoholic, or standardized extraction methods, containing over 400 identified chemical constituents with glycyrrhizin serving as the primary bioactive compound.

Historical & Cultural Context

Licorice root has been a foundational herb in Traditional Chinese Medicine for over 2,000 years, traditionally used for respiratory conditions and digestive complaints. It has documented use in Ayurvedic medicine for anti-inflammatory and immunomodulatory purposes, with historical applications across Mediterranean and Middle Eastern traditional medicine systems.

Health Benefits

• Anti-inflammatory support through inhibition of prostaglandins and leukotrienes (strong preclinical evidence)
• Antiviral activity against respiratory viruses including H5N1 influenza and RSV at 25-50 µg/ml concentrations (in-vitro evidence)
• Enhanced wound healing for second-degree burns with complete healing by day 19 in animal models (preliminary evidence)
• Immunomodulatory effects through elevation of IgG, IgM, and IgA antibody levels (preclinical evidence)
• Anxiolytic effects and stress response reduction in chronic mild stress models (animal evidence)

How It Works

Glycyrrhizin inhibits 11β-hydroxysteroid dehydrogenase type 2, prolonging cortisol activity and reducing inflammation through suppressed prostaglandin E2 and leukotriene synthesis. The triterpene saponins directly bind to viral envelope proteins, preventing cellular entry of influenza and RSV. Glycyrrhetinic acid activates fibroblast growth factor pathways, accelerating collagen deposition and epithelial regeneration during wound healing.

Scientific Research

Clinical evidence includes a randomized controlled trial in COVID-19 patients showing improved inflammatory markers (CRP and ALT) though no effect on primary symptoms (PMID: 37847472), and a trial demonstrating therapeutic benefit in 36 chronic asthma patients. A comprehensive review analyzed 198 peer-reviewed articles published between 1956 and 2021 documenting licorice's therapeutic applications.

Clinical Summary

In vitro studies demonstrate antiviral efficacy at 25-50 µg/ml concentrations against H5N1 influenza and RSV with 80-90% viral inhibition. Small clinical trials (n=30-60) show accelerated healing of second-degree burns when applied topically, reducing healing time by 3-5 days compared to controls. Anti-inflammatory effects are well-documented in preclinical models, but large-scale human trials for systemic inflammation remain limited. Evidence is strongest for topical wound applications and moderate for respiratory viral prevention.

Nutritional Profile

Glycyrrhiza glabra (Licorice root) contains a complex array of bioactive compounds rather than significant macronutrient contributions. Key bioactive constituents include: Glycyrrhizin (glycyrrhizinic acid) at 2-25% dry weight (typically 4-6% in commercial root), the primary triterpenoid saponin responsible for sweetness (~50x sweeter than sucrose) and most pharmacological activity; Glycyrrhetinic acid (aglycone metabolite of glycyrrhizin, formed via gut bacterial hydrolysis, primary systemically active form with ~70-80% oral bioavailability after conversion); Flavonoids at 1-3% dry weight including liquiritin (0.5-1.2%), isoliquiritin, liquiritigenin, isoliquiritigenin, glabridin (0.1-0.3% in root extract), and formononetin; Polysaccharides (glycyrrhizan) at 3-5% contributing immunomodulatory effects; Coumarins including liqcoumarin, glycycoumarin, and umbelliferone at trace levels (<0.1%); Sterols including beta-sitosterol and stigmasterol at approximately 0.05-0.1%; Volatile oils at 0.047% including anethole, fenchone, and linalool. Macronutrient profile per 100g dried root: carbohydrates 50-60g (predominantly starch and fiber), dietary fiber 7-10g, protein 6-8g (low bioavailability), fat <1g. Micronutrients include potassium (approximately 1150 mg/100g, notably high), calcium (370 mg/100g), magnesium (85 mg/100g), phosphorus (130 mg/100g), iron (7-8 mg/100g), zinc (1.2 mg/100g), and trace selenium. Vitamins present in modest amounts: thiamine (B1) ~0.03 mg/100g, riboflavin (B2) ~0.05 mg/100g, niacin ~0.4 mg/100g. Bioavailability notes: Glycyrrhizin undergoes extensive first-pass intestinal metabolism to glycyrrhetinic acid; peak plasma concentration of glycyrrhetinic acid reached at 8-24 hours post-ingestion due to enterohepatic recirculation; flavonoids such as glabridin show moderate bioavailability (~15-20%) with enhanced absorption in lipid-rich matrices; standardized extracts are typically normalized to 20-25% glycyrrhizin content for clinical applications.

Preparation & Dosage

Clinical studies have used topical hydrogels at 5-20% w/w concentrations for wound healing, and 30 mg/mL concentrations in traditional beverage preparations. Therapeutic glycyrrhizin concentrations for antiviral effects range from 25-50 µg/ml in cell-based assays. Most clinical studies employed glycyrrhizin-standardized extracts. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Ginger, Echinacea, Elderberry, Vitamin C, Zinc

Safety & Interactions

Glycyrrhizin can cause pseudoaldosteronism with chronic use above 100mg daily, leading to hypertension, hypokalemia, and sodium retention. Contraindicated with ACE inhibitors, diuretics, and digoxin due to potassium depletion risks. Pregnancy safety is unclear as glycyrrhizin may affect fetal cortisol levels and should be avoided. Individuals with hypertension, kidney disease, or heart conditions should avoid licorice supplements containing glycyrrhizin.