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Licorice is the common name for plants of the Glycyrrhiza family. It may contain protective flavanoids. Glycyrrhetic acid (a component of licorice) may decrease testosterone and increase cortisol.

Our evidence-based analysis on licorice features 233 unique references to scientific papers.

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Summary of Licorice

Primary information, health benefits, side effects, usage, and other important details

Licorice (Glycyrrhiza plants, usually the Glabra species) have been used in Traditional Chinese Medicine to fairly good acclaim for various digestive and health problems, and as a general vitality promoting agent. Licorice is also routinely used as a candy product, and is inherently a functional food rather than just a candy (as the oil containing the traditional licorice flavor also contains some bioactive compounds).

One of the most important compounds in Licorice appears to be Glycyrrhizin, which is the sugar-bound form of Glycyrrhetic Acid (there exists both an alpha and beta isomer, with the latter 18β-Hydroxyglycyrrhetic acid being referred to frequently). This compound is highly relevant when consuming pure licorice extracts due to its good absorption and relatively high content, but also underlies a fairly reliable reduction in testosterone and a highly reliable increase in circulating cortisol after consumption. Both of these effects are dose-dependent and not associated with any toxicological effects (and reversed upon cessation of Licorice), but many persons may want to avoid Glycyrrhizin and Glycyrrhetic Acid due to these reasons.

An ethanolic extract of Licorice, sometimes used in supplements, is able to concentrate flavanoids and isoflavanoid compounds with a relatively low Glycyrrhizin content. Some of these flavanoids, including Glabridol as well as the Liquirtigenin class of flavanoids, appear to be the ones that exert properties that would be seen as 'beneficial'.

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How to Take

Recommended dosage, active amounts, other details

Prior to supplementing Licorice, please be aware of Glycyrrhizin (the agent that increases cortisol and reduces testosterone) and, if these results are not desired, try to get products with low Glycyrrhizin content (less than 500mg total dose daily). 150mg has been confirmed to not influence these hormones

Traditional Chinese Medicine recommends a decoction of 8-15g Licorice for health protection and up to 100g for disease states. Consumption of licorice in these doses as a food product does confer the same properties as supplementation, but the caloric and carbohydrate intake from either the root of confectionaries derived from the root need to be accounted for.

With supplementation, intakes of Licorice in the range of 150-300mg daily appear to be most commonly used and intakes of Deglyccyrhizinated (without Glycyrrhizin) up to 1800mg daily for 4 weeks are not associated with toxicity in humans.

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Human Effect Matrix

Unlocked for Examine members

The Human Effect Matrix summarizes human studies to tell you what effects Licorice has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-c Notable Very High See 2 studies
The decrease in oxidation of LDL seen with either licorice of isolated Glabridin appears to exceed 20% and is more than other supplements
grade-c Minor - See study
Topical application of licorice is able to reduce canker sore size and pain associated with canker sores
grade-c Minor Very High See all 3 studies
Appears to increase cortisol at higher doses (500mg or more), with no significant influence at lower doses; this is related to the glycyrrhizin content, and would not occur in deglycyrrhizinated supplements
grade-c Minor Very High See 2 studies
A decrease in lipid peroxidation is noted with licorice consumption, not to a remarkable degree
grade-c Minor Moderate See all 6 studies
There appears to be a testosterone reduction associated with intake of licorice above 500mg, but the magnitude of this reduction is quite variable and there is no robust information on the topic
grade-c - - See study
No significant interaction between adiponectin and licorice
grade-c - - See study
No significant influence on fat mass
grade-c - - See study
grade-c - - See study
No significant influence of licorice on HDL
grade-c - - See study
No significant changes in fasting insulin levels
grade-c - - See study
No significant changes in insulin sensitivity following licorice ingestion
grade-c - - See study
No significant influence on LDL cholesterol seems apparent
grade-c - - See study
No significant alterations in lean mass associated with licorice
grade-c - - See study
No significant influence on total cholesterol is observed following licorice ingestion
grade-c - - See study
No significant influence on triglycerides
grade-c - - See study
No significant interactions with body weight associated with licorice ingestion
grade-d Notable Moderate See 2 studies
Has the potential to increase blood pressure secondary to increasing cortisol; this is notable as it seems hypertensives are at greater risk from an adverse reaction to high dose licorice and as such should exert caution when using this herb (related to the glycyrrhizin content, and deglycyrrhizinated supplements should not have the same risk)
grade-d Minor - See study
An increase in parathyroid hormone has been noted with consumption of licorice
grade-d - Very High See 2 studies
No significant alterations in serum estrogen
grade-d - - See study
No significant alterations in follicle stimulating hormone seen with licorice consumption
grade-d - High See all 3 studies
More evidence than not suggests no significant changes in lutenizing hormone, although limited evidence suggests an increase of minor magnitude.
grade-d - - See study
Prolactin appears unaffected following licorice consumption
grade-d - - See study
No significant alterations in SHBG levels following supplementation

Studies Excluded from Consideration

  • Duplication in Pubmed, other duplication added to Table[1]

  • Confounded with other nutrients[2][3][4][5]

  • Pharmacokinetic study[6]

  • No pure licorice group[7]

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Things to Note

Other Functions:

Also Known As

Licorice, Liquorice, Yashtimadhu, Glycyrrhiza, Glycyrrhiza Uralensis, Glycyrrhiza Glabra

Goes Well With

  • P-Glycoprotein inhibitors (increases Glabridin levels in serum and the brain)

  • Lycopene (in inhibiting LDL oxidation)

Caution Notice

Glabridin potently inhibits CYP3A4 (similar to Hypericum Perforatum) and has the potential for adverse drug-drug interactions.

  • Glabridin (component of Licorice) appears to potently inhibit CYP3A4, an enzyme used in the metabolism of many drugs. There is potential for adverse drug-nutrient interactions

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Click here to see all 233 references.