Home Ingredients Glabridin (Licorice Isoflavone)
CardiovascularMetabolic HealthAntioxidant

Glabridin (Licorice Isoflavone)

Glycyrrhiza glabra L. — isolated isoflavonoid
Evidence Level
Limited
3 Clinical Trials
5 Documented Benefits
2/5 Evidence Score

Glabridin is an isoflavonoid specific to Glycyrrhiza glabra L. (licorice root), distinct from glycyrrhizin (the licorice compound that causes pseudoaldosteronism at high doses). Its human evidence comes mostly from licorice extracts and licorice flavonoid oil rather than pure glabridin: a 6-month trial of a glycyrrhizin-free licorice-root extract providing about 60 mg/day of glabridin reduced plasma LDL oxidation by roughly 20%, and licorice flavonoid oil (LFO) reduced body fat in moderately overweight adults, mainly at higher doses (a second LFO trial was null). Glucose-metabolism effects are so far only preclinical (animal). A key limitation is low oral bioavailability (~7.5%), so oil-emulsion delivery such as Glavonoid® is preferred for systemic effects. Overall: a promising multi-target compound whose oral human evidence is limited and largely based on glabridin-containing extracts and oils rather than the isolated compound.

Studied Dose Human LDL-oxidation evidence used a licorice-root extract (~60 mg/day glabridin); body-fat trials used licorice flavonoid oil (LFO) 300–900 mg/day. No established pure-glabridin human dose. Oral bioavailability ~7.5%.
Active Compound Glabridin, an isoflavonoid specific to Glycyrrhiza glabra (licorice root); distinct from glycyrrhizin; low oral bioavailability (~7.5%).

Benefits

LDL oxidation reduction (6-month trial)

In a 6-month human trial, a glycyrrhizin-free licorice-root extract providing about 60 mg/day of glabridin reduced plasma LDL oxidation by roughly 20% — an atheroprotective effect on the oxidative-modification step of atherogenesis, distinct from cholesterol-lowering. The evidence is for the glabridin-containing extract, not isolated glabridin.

Supported by Trial 1

Glucose and body-fat effects (preclinical)

In diabetic-mouse models, glabridin and licorice flavonoids lowered elevated blood glucose and abdominal-fat accumulation, consistent with AMPK activation. These effects are preclinical — no human glabridin trial in type 2 diabetes has been conducted.

Supported by Trial 2

Body-fat reduction (licorice flavonoid oil)

In moderately overweight adults, 8 weeks of licorice flavonoid oil (LFO, which contains glabridin) reduced total and visceral body fat, with body weight, BMI, and LDL-cholesterol falling mainly at the highest (900 mg) dose. The evidence is for LFO rather than pure glabridin, and a separate LFO trial found no significant effect versus placebo.

Supported by Trial 3

Anti-atherogenic activity

Glabridin is the most abundant and potent antioxidant among the licorice constituents tested for LDL oxidation inhibition. The ring-B 2'-hydroxyl is critical to activity per structure-activity studies — clean mechanistic rationale supporting the clinical LDL oxidation findings.

Supported by Trial 1, Trial 2

Anti-inflammatory effects

NF-κB pathway suppression and reduced inflammatory cytokines in cellular and animal models. Mechanistic complement to the metabolic and atheroprotective effects observed in human trials.

Supported by Trial 2

Mechanism of action

1

LDL oxidation inhibition (primary atheroprotective mechanism)

Glabridin directly inhibits LDL oxidation — the lipid peroxidation step that initiates foam cell formation in atherogenesis. Ring-B 2'-hydroxyl is critical to activity per structure-activity studies. Distinct from cholesterol-lowering: addresses oxidative modification rather than circulating cholesterol levels.

2

AMPK activation (metabolic mechanism)

Glabridin activates AMP-activated protein kinase (AMPK), the central metabolic energy sensor. Downstream effects include increased fatty acid oxidation and GLUT4 translocation supporting glucose uptake. Mechanism for the multi-target metabolic effects.

3

NF-κB anti-inflammatory pathway suppression

Suppression of NF-κB signaling reduces inflammatory cytokine production. Anti-inflammatory mechanism complementing the metabolic effects.

4

Mild estrogen receptor binding (phytoestrogenic)

Mild phytoestrogenic activity via estrogen receptor binding. Caution applies in hormone-sensitive conditions (estrogen-receptor-positive breast cancer, endometriosis, etc.).

5

Low oral bioavailability (~7.5%) — delivery limitation

Critical pharmacokinetic limitation: oral bioavailability is only about 7.5%. Glavonoid® MCT-oil delivery system from Kaneka substantially enhances bioavailability vs purified glabridin — practical preference for systemic effects. Topical formulations bypass this limitation for skin-lightening applications.

Clinical trials

1
Licorice-Root Extract LDL Oxidation 6-Month Trial
PubMed

Six-month human trial of a glycyrrhizin-free licorice-root extract providing about 60 mg/day of glabridin. (Carmeli et al.)

Healthy adults.

Plasma LDL oxidation and oxidative-stress markers fell by roughly 20% over 6 months. The evidence is from the glabridin-containing licorice-root extract, not isolated glabridin; earlier work (Fuhrman) similarly used licorice extract.

2
Glucose Metabolism — Preclinical (Animal) Evidence

Diabetic-mouse model (KK-Ay) of glabridin and licorice flavonoids on blood glucose and abdominal fat.

Diabetic mice (KK-Ay); no human glabridin diabetes trial exists.

In diabetic mice, glabridin and licorice flavonoids lowered elevated blood glucose and abdominal-fat accumulation, consistent with AMPK activation. Preclinical only — these effects have not been demonstrated in a human diabetes trial.

3
Licorice Flavonoid Oil (LFO) Body-Fat 8-Week Trial
PubMed

Randomized, double-blind, placebo-controlled 8-week trial of licorice flavonoid oil (LFO, containing glabridin) at 300, 600, or 900 mg in 84 moderately overweight adults. (Tominaga et al. 2009, Obes Res Clin Pract)

84 moderately overweight adults (BMI 24–30).

Total body fat fell across the LFO doses; visceral fat, body weight, BMI, and LDL-cholesterol decreased mainly at the highest (900 mg) dose. The evidence is for LFO (a glabridin-containing oil), not pure glabridin. A separate LFO trial (Bell 2011, n=22) found no significant difference versus placebo.

Side effects and drug interactions

Common Potential side effects

Generally well-tolerated — flavonoid fraction (NO glycyrrhizin pseudoaldosteronism risk).
Mild GI upset (rare).
Allergic reactions in licorice-sensitive individuals (rare).
Pregnancy/lactation: limited data; precautionary avoidance.
Estrogen-sensitive conditions: theoretical mild phytoestrogenic effects — caution.
Long-term safety: a 6-month human trial of a glabridin-containing licorice extract was well tolerated.
Delivery limitation: ~7.5% bioavailability — branded delivery systems (Glavonoid® MCT) preferred.

Important Drug interactions

Statins: compatible; complementary cholesterol effects.
Antidiabetic medications: theoretical compatible/additive glucose effects (Hattori 2019 evidence) — monitor blood glucose.
Antihypertensives: theoretical mild effects.
Anticoagulants: minimal interactions documented.
Most medications: well-tolerated combination profile.
Hormone-sensitive treatments (tamoxifen, etc.): caution due to mild phytoestrogenic activity.
Cytochrome P450 substrates: theoretical interactions (lower with flavonoid fraction vs glycyrrhizin).

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Frequently asked questions about Glabridin (Licorice Isoflavone)

What is glabridin used for?

Glabridin is a flavonoid from licorice root studied mainly for oral cardiovascular and metabolic support. Its best-supported effects are reducing LDL oxidation (as part of a licorice extract) and helping reduce body fat (as licorice flavonoid oil). It is distinct from glycyrrhizin, the licorice compound that can raise blood pressure.

How is glabridin taken?

Because pure glabridin is poorly absorbed (about 7.5% oral bioavailability), it is usually taken as a licorice flavonoid oil (such as Glavonoid) or within a licorice extract for systemic effects. Follow the product’s directions.

What does the evidence show?

Human evidence is limited: a 6-month licorice-extract trial reduced LDL oxidation by about 20%, and licorice flavonoid oil reduced body fat in overweight adults (mainly at higher doses), though a second trial found no effect. Glucose-lowering effects have so far only been seen in animal studies.

Is glabridin safe?

The glabridin/flavonoid fraction avoids the glycyrrhizin that can raise blood pressure, and licorice flavonoid oil has been well tolerated in trials. Data in pregnancy and in estrogen-sensitive conditions are limited, so caution is advised. Follow labeling and check with a doctor if unsure.

What is Glabridin?

Glabridin is an isoflavonoid specific to Glycyrrhiza glabra L. (licorice root), distinct from glycyrrhizin (the licorice compound that causes pseudoaldosteronism at high doses).

What is the recommended dosage of Glabridin?

The clinically studied dose is Human LDL-oxidation evidence used a licorice-root extract (~60 mg/day glabridin); body-fat trials used licorice flavonoid oil (LFO) 300–900 mg/day. No established pure-glabridin human dose. Oral bioavailability ~7.5%. Always follow the product label and check with a healthcare provider for personal advice.

Is Glabridin safe, and does it have side effects?

For most healthy adults, Glabridin is well tolerated at studied doses. Reported effects can include: Generally well-tolerated — flavonoid fraction (NO glycyrrhizin pseudoaldosteronism risk). Mild GI upset (rare). It may also interact with some medications. Glabridin is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Glabridin interact with any medications?

Possible interactions include: Statins: compatible; complementary cholesterol effects. Antidiabetic medications: theoretical compatible/additive glucose effects (Hattori 2019 evidence) — monitor blood glucose. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Glabridin?

NutraSmarts rates the evidence for Glabridin as Limited (2 out of 5). It is backed by 3 clinical trials and 5 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(5 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Fuhrman B, Volkova N, Kaplan M, Presser D, Attias J, Hayek T, Aviram M Antiatherosclerotic effects of licorice extract supplementation on hypercholesterolemic patients: increased resistance of LDL to atherogenic modifications, reduced plasma lipid levels, and decreased systolic blood pressure Nutrition. 2002;18(3):268-73. doi:10.1016/s0899-9007(01)00753-5.PubMedUsed to support: Human clinical study of licorice root extract (glabridin-containing) 0.1 g/day × 1 month in hypercholesterolemic patients: LDL resistance to oxidation increased 55%, LDL aggregation reduced 28%, LDL cholesterol −9%, triglycerides −14%, systolic BP −10%. Supports LDL oxidation reduction and anti-atherogenic activity. Note: this study uses licorice extract containing glabridin as its major polyphenol, not isolated glabridin.
  2. Fuhrman B, Buch S, Vaya J, Belinky PA, Coleman R, Hayek T, Aviram M Licorice extract and its major polyphenol glabridin protect low-density lipoprotein against lipid peroxidation: in vitro and ex vivo studies in humans and in atherosclerotic apolipoprotein E-deficient mice American Journal of Clinical Nutrition. 1997;66(2):267-75. doi:10.1093/ajcn/66.2.267.PubMedUsed to support: Human ex vivo study (n=10 normolipidemic subjects) plus in vitro: purified glabridin specifically inhibited LDL lipid peroxidation via free-radical scavenging; licorice extract supplementation in humans rendered isolated LDL more resistant to oxidation. First study to identify glabridin as the key antiperoxidative polyphenol in licorice. Supports LDL oxidation reduction and anti-atherogenic activity for glabridin specifically.
  3. Aoki F, Nakagawa K, Kitano M, Ikematsu H, Nakamura K, Yokota S, Tominaga Y, Arai N, Mae T Clinical safety of licorice flavonoid oil (LFO) and pharmacokinetics of glabridin in healthy humans Journal of the American College of Nutrition. 2007;26(3):209-18. doi:10.1080/07315724.2007.10719603.PubMedUsed to support: Human RCT of glabridin-containing licorice flavonoid oil (LFO) at 300–1200 mg/day × 4 weeks in healthy adults: established safety profile with no clinically meaningful hematological or biochemical changes; characterized glabridin oral pharmacokinetics in humans. Supports established clinical safety basis for glabridin use.
  4. Carmeli E, et al. The effect of an endogenous antioxidant glabridin on oxidized LDL. J Basic Clin Physiol Pharmacol. 2008;.PubMedUsed to support: Six-month human trial of a glycyrrhizin-free licorice-root extract (~60 mg/day glabridin) that reduced LDL oxidation by ~20%. The human LDL-oxidation evidence is from the glabridin-containing extract, not isolated glabridin.
  5. Tominaga Y, et al. Licorice flavonoid oil reduces total body fat and visceral fat in overweight subjects: A randomized, double-blind, placebo-controlled study. Obes Res Clin Pract. 2009;doi:10.1016/j.orcp.2009.04.005.PubMedUsed to support: 8-week RCT of licorice flavonoid oil (LFO) 300–900 mg in 84 moderately overweight adults: total body fat fell across doses, with visceral fat, body weight, BMI, and LDL-C reduced mainly at 900 mg. Evidence is for LFO (glabridin-containing oil), not pure glabridin.