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Liquorice Root Extract

Also known as: Liquorice root extract, Licorice extract, Licorice flavonoids, Glycyrrhiza glabra

Overview

Liquorice root extract is derived from the roots of Glycyrrhiza glabra, a leguminous plant with a long history of use in traditional herbal medicine. Its primary active compounds include glycyrrhizic acid, glycyrrhetinic acid, liquiritigenin, and isoliquiritigenin. This extract is commonly used for various health applications, including gastrointestinal disorders, liver support, and the management of oral mucosal ulcers. It is also being investigated for its potential benefits in hypercholesterolemia, hypertension, and neuroprotection. The extract exhibits anti-inflammatory, antioxidant, immunomodulatory, and enzyme inhibitory properties, contributing to its diverse therapeutic effects. While research on liquorice root extract is moderate, with several clinical trials and systematic reviews available, the evidence quality is mixed, often limited by small sample sizes and variability in extract standardization.

Benefits

Liquorice root extract offers several evidence-based benefits. A systematic review of six randomized controlled trials (RCTs) involving 314 subjects found that topical licorice significantly reduced pain and ulcer size in recurrent aphthous stomatitis, attributed to its anti-inflammatory and antioxidant effects. For cardiovascular health, a meta-analysis of 26 clinical trials (n=985) demonstrated that licorice flavonoid oil reduced LDL cholesterol by approximately 9% and systolic blood pressure by about 10%, with positive effects on LDL oxidation and carotid intima-media thickness. Preclinical studies, including a systematic review and meta-analysis, have shown efficient anti-inflammatory effects of licorice extract and its compounds in ulcerative colitis models, supporting the rationale for further clinical trials. Additionally, in vitro studies suggest neuroprotective effects, with flavonoids like liquiritigenin and isoliquiritigenin crossing the blood-brain barrier and reducing oxidative stress. While potential liver protective and general gastrointestinal benefits are reported, more robust clinical data are needed to confirm these effects.

How it works

Liquorice root extract exerts its effects through multiple biological pathways. Its primary anti-inflammatory action involves the inhibition of pro-inflammatory cytokines and modulation of immune responses. The extract also demonstrates significant antioxidant activity by reducing reactive oxygen species. A key mechanism involves the inhibition of the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (11-beta-HSD2) by glycyrrhizic acid, which can lead to mineralocorticoid-like effects. Flavonoids within the extract, such as liquiritigenin and isoliquiritigenin, contribute to its antioxidant properties and have shown good blood-brain barrier permeability. Glycyrrhizic acid is metabolized in the gut to its active form, glycyrrhetinic acid, which is responsible for many of its systemic effects. The extract interacts with various body systems, including the gastrointestinal mucosa, vascular endothelium, immune cells, and potentially the central nervous system.

Side effects

While generally safe at recommended doses, liquorice root extract, particularly due to its glycyrrhizic acid content, carries known risks. Common side effects, occurring in over 5% of users, include hypertension (high blood pressure), hypokalemia (low potassium levels), and edema (fluid retention), primarily due to its mineralocorticoid-like effects. Uncommon side effects (1-5%) may include gastrointestinal discomfort. Rare but severe side effects (less than 1%) can involve pseudoaldosteronism and cardiac arrhythmias. Liquorice root extract can interact with several medications, including antihypertensives, diuretics, corticosteroids, and drugs that affect potassium levels, potentially exacerbating their effects or leading to adverse outcomes. It is contraindicated in individuals with pre-existing hypertension, heart failure, kidney disease, and during pregnancy. Caution is advised for elderly individuals and those with existing cardiovascular risk factors due to the potential for blood pressure elevation and electrolyte imbalances.

Dosage

The optimal dosage of liquorice root extract varies significantly depending on the specific indication and the standardization of the extract. For cardiovascular benefits, studies using licorice flavonoid oil have typically employed doses standardized to approximately 4 mg of glabridin daily. Clinical trials have utilized a wide range of doses, from 0.1 g/day to several hundred mg/day of standardized extracts. The maximum safe dose is not well-established, but consumption of more than 100 mg/day of glycyrrhizic acid is generally linked to an increased risk of adverse effects such as hypertension and hypokalemia. For topical applications, such as for oral ulcers, the extract is typically used multiple times daily. For internal use, especially for gastrointestinal or oral health, deglycyrrhizinated licorice (DGL) is often preferred as it minimizes the risk of mineralocorticoid side effects associated with glycyrrhizic acid. Effects on blood pressure and lipids may take several months to manifest. No specific cofactors are required, but monitoring electrolyte levels, particularly potassium, is recommended during use.

FAQs

Is licorice root extract safe for long-term use?

Prolonged use of extracts containing glycyrrhizic acid can lead to hypertension and hypokalemia. Deglycyrrhizinated licorice (DGL) forms are generally safer for long-term use, especially for gastrointestinal and oral health.

Can licorice extract help with high blood pressure?

While licorice flavonoid oil may reduce LDL cholesterol and improve vascular markers, extracts high in glycyrrhizic acid can paradoxically raise blood pressure, requiring careful monitoring.

How quickly does licorice extract work for oral ulcers?

Topical application of licorice extract can reduce pain and ulcer size within days to weeks, with significant improvements often observed relatively quickly.

Does licorice extract have neuroprotective effects?

Preclinical evidence suggests that licorice flavonoids possess antioxidant and neuroprotective potential, but more clinical research is needed to confirm these effects in humans.

Is deglycyrrhizinated licorice (DGL) preferable?

Yes, DGL is generally preferred as it significantly reduces the risk of mineralocorticoid side effects like hypertension and hypokalemia, making it safer for long-term and specific uses.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/35671864/ – This systematic review and meta-analysis of preclinical studies investigated the anti-inflammatory effects of licorice extract and its compounds in ulcerative colitis models. The findings indicated efficient anti-inflammatory properties, supporting the rationale for further clinical trials despite limitations such as risk of bias and the preclinical nature of the studies.
https://pubmed.ncbi.nlm.nih.gov/31874059/ – This comprehensive review explored the pharmacological efficacy and safety of licorice. It highlighted the extract's enzyme inhibition and antioxidant properties, discussing its traditional and emerging clinical applications. The review also addressed safety concerns related to glycyrrhizic acid content while emphasizing the broad therapeutic potential of licorice.
https://www.alzdiscovery.org/uploads/cognitive_vitality_media/Licorice-Flavonoids-Cognitive-Vitality-For-Researchers.pdf – This meta-analysis of 26 clinical trials (n=985) focused on the cardiovascular effects of licorice flavonoid oil. It found significant reductions in LDL cholesterol (~9%) and systolic blood pressure (~10%) in hypercholesterolemic subjects. The study also noted positive effects on LDL oxidation and carotid intima-media thickness, though some benefits were not sustained after cessation of treatment.
https://pubmed.ncbi.nlm.nih.gov/37786470/ – This systematic review evaluated the efficacy of topical licorice for recurrent aphthous stomatitis, analyzing six RCTs with 314 subjects. The review concluded that topical licorice significantly reduced pain and ulcer size, attributing these effects to its anti-inflammatory and antioxidant properties. The studies were of moderate quality, with consistent positive findings.
https://www.mdpi.com/2072-6643/16/21/3768 – This systematic review with meta-analysis confirmed the metabolic and blood pressure changes associated with licorice intake. It underscored the importance of dose control due to the potential hypertensive effects of glycyrrhizic acid, providing further evidence for the need for careful consideration of extract standardization and individual patient factors.