Ellagic Acid

Pharmacology & Research

Ellagic acid is one of the most-studied dietary polyphenols, and one of the most over-attributed — because “ellagic acid” is really three different things. First, in plants it occurs mostly bound as ellagitannins (punicalagins, sanguiin, etc.), so the substance in a “pomegranate/ellagic acid” study is usually an ellagitannin extract, not the free molecule. Second, free ellagic acid is very poorly absorbed — plasma peaks around 0.06 µmol/L and absorption saturates, so swallowing more buys little ^{15Reference 15Seeram NP et al. · 2004Bioavailability of ellagic acid in human plasma after consumption of ellagitannins from pomegranate (Punica granatum L.) juiceView study →}. Third, the species that actually circulate at meaningful concentrations are the gut-microbial metabolites urolithins (urolithin A/B), and only some people make them well — a person’s “urolithin metabotype” (A, B, or 0) gates the whole story ^{13,18Reference 13Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →Reference 18Cortés-Martín A et al. · 2018The gut microbiota urolithin metabotypes revisited — the human metabolism of ellagic acid is mainly determined by agingView study →}. So efficacy credited to “ellagic acid” usually belongs to an ellagitannin source or a downstream metabolite, and is filtered through the microbiome. Read every claim with that three-layer caveat.

1. Cardiovascular (pomegranate/ellagitannin)

The best-supported application — but the tested agent is pomegranate, not ellagic acid. Meta-analyses of RCTs find pomegranate juice/extract lowers both systolic and diastolic blood pressure ^{1Reference 1Sahebkar A et al. · 2017Meta-analysisEffects of pomegranate juice on blood pressure — a systematic review and meta-analysis of randomised controlled trialsView study →}, with later meta-analyses reaffirming a modest systolic effect ^{2Reference 2Bahari H et al. · 2024Meta-analysisThe effects of pomegranate consumption on blood pressure in adults — a systematic review and meta-analysisView study →} and a dose-response across cardiometabolic risk factors ^{3Reference 3Mohammadi S et al. · 2025Meta-analysisImpacts of supplementation with pomegranate on cardiometabolic risk factors — a systematic review and dose-response meta-analysisView study →}. Proposed mechanism is punicalagin/ellagitannin-driven ACE and NF-κB modulation with eNOS/NO support.

Gap: every one of these is a whole-pomegranate intervention — the active fraction cannot be cleanly attributed to ellagic acid versus anthocyanins, intact punicalagins, or urolithins; there is no pure-ellagic-acid BP RCT of comparable weight, and heterogeneity (juice vs extract, dose, duration) is high ^{1,2Reference 1Sahebkar A et al. · 2017Meta-analysisEffects of pomegranate juice on blood pressure — a systematic review and meta-analysis of randomised controlled trialsView study →Reference 2Bahari H et al. · 2024Meta-analysisThe effects of pomegranate consumption on blood pressure in adults — a systematic review and meta-analysisView study →}.

2. Urolithin A — muscle & mitochondria

The flashiest human data — and a different molecule. The trials give synthetic urolithin A (a supplement), precisely to bypass the absorption and metabotype problems of ellagic acid: a first-in-human study found it safe and inducing a mitochondrial/mitophagy signature ^{4Reference 4Andreux PA et al. · 2019The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humansView study →}, a 4-month RCT improved muscle strength and exercise-performance biomarkers ^{5Reference 5Singh A et al. · 2022RCTUrolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomised trial in middle-aged adultsView study →}, and an RCT in older adults improved muscle endurance and mitochondrial markers ^{6Reference 6Liu S et al. · 2022RCTEffect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults — a randomised clinical trialView study →}, with an athlete RCT adding endurance/inflammation effects ^{7Reference 7Zhao H et al. · 2024RCTAssessment of urolithin A effects on muscle endurance, strength, inflammation, oxidative stress and protein metabolism in male athletes with resistance training — an 8-week randomised, double-blind, placebo-controlled studyView study →}.

Gap: this is good evidence for urolithin A, not ellagic acid. Functional endpoints are modest and biomarker-led, the trials are industry-associated, and — crucially — the results do not transfer to “ellagic acid supplementation” unless you are a urolithin-A producer, and even then ellagic acid delivers far less urolithin A than dosing the metabolite ^{4,6Reference 4Andreux PA et al. · 2019The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humansView study →Reference 6Liu S et al. · 2022RCTEffect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults — a randomised clinical trialView study →}.

3. Metabolic — glucose & insulin

The rare genuine pure-isolate human data. Small RCTs of ellagic acid (~180–500 mg/day) report improved insulin sensitivity in metabolic syndrome ^{8Reference 8Hidalgo-Lozada GM et al. · 2022RCTEllagic acid effect on the components of metabolic syndrome, insulin sensitivity and insulin secretion — a randomised, double-blind, placebo-controlled clinical trialView study →}, reduced insulin resistance with SIRT1/Fetuin-A changes in type 2 diabetes ^{9Reference 9Ghadimi M et al. · 2021RCTDecreased insulin resistance in diabetic patients by influencing Sirtuin1 and Fetuin-A following supplementation with ellagic acid — a randomised controlled trialView study →}, and improved insulin resistance and hormonal measures in PCOS ^{10Reference 10Kazemi M et al. · 2021RCTRandomised double-blind clinical trial evaluating the ellagic acid effects on insulin resistance, oxidative stress and sex-hormone levels in women with polycystic ovarian syndromeView study →}.

Gap: small (tens of patients), short (8–12 weeks), surrogate/mechanistic endpoints (HOMA-IR, SIRT1, MDA), and clustered in a few research groups with no independent large-scale replication and no hard outcomes. Promising, genuinely the isolate, but early ^{8,10Reference 8Hidalgo-Lozada GM et al. · 2022RCTEllagic acid effect on the components of metabolic syndrome, insulin sensitivity and insulin secretion — a randomised, double-blind, placebo-controlled clinical trialView study →Reference 10Kazemi M et al. · 2021RCTRandomised double-blind clinical trial evaluating the ellagic acid effects on insulin resistance, oxidative stress and sex-hormone levels in women with polycystic ovarian syndromeView study →}.

4. Anti-inflammatory & anticancer

Ellagic acid shifts oxidative-stress markers (notably MDA) and some inflammatory cytokines across the metabolic RCTs and a single MS-with-depressive-symptoms trial ^{11Reference 11Hajiluian G et al. · 2023The effects of ellagic acid supplementation on neurotrophic, inflammation and oxidative stress factors, and IDO gene expression in multiple sclerosis patients with mild to moderate depressive symptomsView study →}, while its anticancer pharmacology — apoptosis, cell-cycle arrest, anti-angiogenesis — is extensively documented in the laboratory ^{12Reference 12Ceci C et al. · 2018ReviewExperimental evidence of the antitumour, antimetastatic and antiangiogenic activity of ellagic acid — a reviewView study →}.

Gap: the human anti-inflammatory data are biomarker-only with unestablished clinical meaning, and the anticancer evidence is entirely preclinical — no human efficacy trials, and cell studies use concentrations far above achievable plasma levels. Mechanistically rich, clinically unproven ^{11,12Reference 11Hajiluian G et al. · 2023The effects of ellagic acid supplementation on neurotrophic, inflammation and oxidative stress factors, and IDO gene expression in multiple sclerosis patients with mild to moderate depressive symptomsView study →Reference 12Ceci C et al. · 2018ReviewExperimental evidence of the antitumour, antimetastatic and antiangiogenic activity of ellagic acid — a reviewView study →}.

Mechanisms

Target / pathway	Acting species	Evidence	Maps to
Antioxidant / radical scavenging (MDA ↓)	ellagic acid (isolate)	human biomarker RCTs	metabolic, anti-inflammatory
Anti-inflammatory — NF-κB ↓, CRP/adhesion ↓	ellagitannins + ellagic acid + urolithin A	human (pomegranate metas; urolithin A RCTs)	cardiovascular, anti-inflammatory
Endothelial / vascular — ACE ↓, eNOS/NO ↑	ellagitannins (punicalagin)	human RCT meta-analyses	blood pressure
Mitophagy / mitochondrial biogenesis (PGC-1α)	urolithin A (metabolite)	human RCTs	muscle, ageing
Insulin sensitisation — SIRT1 ↑, HOMA-IR ↓	ellagic acid (isolate)	small human RCTs	insulin resistance, T2D, PCOS
Pro-apoptotic / anti-angiogenic	ellagic acid, high concentration	preclinical only	anticancer (unproven)

Pharmacokinetics

Ellagic acid is the textbook case of a molecule whose blood levels never match its bench reputation — and it is largely a pro-drug for urolithins. Free ellagic acid has low solubility and only a narrow upper-intestinal absorption window; most dietary ellagic acid arrives bound in ellagitannins that hydrolyse in the gut to release it. Either way little reaches plasma intact: in the classic pomegranate-juice study it peaked at only ~0.06 µmol/L with a sub-hour half-life, cleared within hours ^{15Reference 15Seeram NP et al. · 2004Bioavailability of ellagic acid in human plasma after consumption of ellagitannins from pomegranate (Punica granatum L.) juiceView study →}, and pushing the free-ellagic-acid dose 20-fold does not raise plasma proportionally — absorption saturates. What circulates and persists is the downstream story: ellagic acid reaching the colon is progressively converted by microbiota to urolithins (C → A, and in some people isourolithin A / urolithin B), which are far better absorbed, enter blood as glucuronide/sulfate conjugates in the ~0.2–20 µM range, and are still detectable in urine up to 48 h ^{16,17Reference 16Seeram NP et al. · 2006Pomegranate juice ellagitannin metabolites are present in human plasma and some persist in urine for up to 48 hoursView study →Reference 17Espín JC et al. · 2013Biological significance of urolithins, the gut microbial ellagic-acid-derived metabolites — the evidence so farView study →}.

Crucially this conversion is not universal: people fall into reproducible urolithin metabotypes — A (only urolithin A), B (also isourolithin A/urolithin B), and 0 (essentially none) — consistent across trials regardless of food source, and shifting with age toward metabotype B and non-producers ^{13,18Reference 13Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →Reference 18Cortés-Martín A et al. · 2018The gut microbiota urolithin metabotypes revisited — the human metabolism of ellagic acid is mainly determined by agingView study →}. This is why two people eating the same pomegranate get very different internal exposures, and why the modern muscle trials dose urolithin A directly. The honest read: cell studies use 10–100 µM ellagic acid, roughly 1,000× above achievable plasma; any real effect is either local in the gut lumen or via urolithins, gated by the microbiome ^{13,15Reference 13Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →Reference 15Seeram NP et al. · 2004Bioavailability of ellagic acid in human plasma after consumption of ellagitannins from pomegranate (Punica granatum L.) juiceView study →}.

Clinical trials

Ellagic acid’s human literature is dominated by pomegranate/ellagitannin interventions (cardiovascular) and, more recently, by urolithin A (a metabolite dosed directly). Genuine pure-ellagic-acid efficacy RCTs are few, small and surrogate-endpoint.

Pure ellagic acid	Pomegranate/ellagitannin	Urolithin A (metabolite)	Anticancer
Few small RCTs (metabolic)	Many RCTs + meta-analyses	Several RCTs	Preclinical only

Last checked: July 2026.

Monoamine oxidase (MAO) inhibition

Unusually among dietary polyphenols, ellagic acid is a moderately potent, MAO-B-preferring inhibitor — a reported IC50 around 9.21 µM (Ki ≈ 7.5 µM) against MAO-B, with only weak MAO-A inhibition ^{14Reference 14Oh JM et al. · 2021Acetylcholinesterase and monoamine oxidase-B inhibitory activities by ellagic acid derivatives isolated from Castanopsis cuspidata var. sieboldiiView study →} (the direction opposite to the MAO-A-preferring flavonols/flavones). An eye-catching nanomolar figure circulating from another paper is internally inconsistent; the ~9 µM value is the trustworthy one. Given ellagic acid’s very poor absorption this is more an in-vitro property than a clinical effect — see the natural MAO inhibitors guide.

Isolate vs. Plant Studies

Ellagic acid is over-attributed in three directions at once. The human cardiovascular evidence is pomegranate/ellagitannin, not free ellagic acid — the active fraction of a pomegranate extract can’t be assigned to ellagic acid over its punicalagins, anthocyanins or downstream urolithins ^{1Reference 1Sahebkar A et al. · 2017Meta-analysisEffects of pomegranate juice on blood pressure — a systematic review and meta-analysis of randomised controlled trialsView study →}. The flashiest human data are a metabolite: the urolithin-A muscle/mitophagy trials dose urolithin A directly, precisely because ellagic acid delivers so little of it, and only in metabotype-A producers ^{4,13Reference 4Andreux PA et al. · 2019The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humansView study →Reference 13Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →}. And in plants ellagic acid is mostly bound as ellagitannins — and the specific ellagitannins that carry activity (sanguiin H-6, castalagin, corilagin, punicalagin, geraniin) are distinct molecules with their own pharmacology, not free ellagic acid. Across this database ellagic acid appears in raspberry leaf, pomegranate, camu-camu, chanca-piedra and bearberry — but usually the note is really about an ellagitannin (sanguiin, castalagin, corilagin) or a hydrolysed total. Read pomegranate trials as ellagitannin evidence, urolithin trials as metabolite evidence, and the small pure-ellagic-acid RCTs as the (thin) evidence for the molecule itself.

Prevalence in Nature

Ellagic acid occurs in plants overwhelmingly bound as ellagitannins — galloyl/hexahydroxydiphenoyl (HHDP) esters of glucose — rather than as the free aglycone, so food tables report total ellagic acid after hydrolysis, which is much higher than the free value ^{21Reference 21Sharifi-Rad J et al. · 2022ReviewEllagic acid — a review on its natural sources, chemical stability and therapeutic potentialView study →}. The richest sources cluster in a few families: pomegranate (punicalagins, concentrated in the peel/rind — up to ~3,900 mg/100 g dry weight, ~50× the edible arils, which is why the peel is the commercial extraction source even though it isn’t eaten); Rubus/Fragaria berries (cloudberry and raspberry the headliners, plus blackberry and strawberry; sanguiin H-6 and lambertianin C are the main ellagitannins); walnuts and pecans (pedunculagin); muscadine grapes (unusual among grapes in carrying ellagitannins); and oak — vescalagin/castalagin leach from barrels, so oak-aged wine and whisky pick up ellagic acid that unoaked drinks lack ^{21,22Reference 21Sharifi-Rad J et al. · 2022ReviewEllagic acid — a review on its natural sources, chemical stability and therapeutic potentialView study →Reference 22Koponen JM et al. · 2007Contents of anthocyanins and ellagitannins in selected foods consumed in FinlandView study →}. See the Content-by-Source chart for edible foods (total-after-hydrolysis basis).

Biosynthetically, gallic acid (from the shikimate pathway) is esterified onto glucose; oxidative C–C coupling of two adjacent galloyl groups forms the hexahydroxydiphenoyl (HHDP) ester that defines ellagitannins, and on hydrolysis the freed HHDP acid spontaneously lactonises into the stable, planar dilactone that is ellagic acid ^{21,23Reference 21Sharifi-Rad J et al. · 2022ReviewEllagic acid — a review on its natural sources, chemical stability and therapeutic potentialView study →Reference 23Clifford MN · 2000Ellagitannins — nature, occurrence and dietary burdenView study →}. There is essentially no non-plant source: it arises only from ingested ellagitannins (then converted to urolithins by gut bacteria).

Discovery & Synthesis

The name is a chemist’s in-joke: “ellagic” is “galle” — French for gallnut — spelled backwards (galle → ellag), signalling both its origin from oak galls (noix de galle) and its kinship with acide gallique, gallic acid. The compound is conventionally credited to Henri Braconnot around 1831, though secondary sources disagree (some cite ~1818, and Chevreul is sometimes named as first noticing it in gallnuts), and no primary indexed source confirms the attribution — so treat “Braconnot, ~1831” as the conventional account rather than a documented fact.

Structurally ellagic acid is a dimeric derivative of gallic acid — the dilactone of hexahydroxydiphenic acid: two gallic-acid units joined head-to-tail by a biaryl bond and locked by two lactone rings into a flat, rigid, four-ring planar polyphenol with four phenolic hydroxyls. That fused, planar, hydrogen-bonding structure is exactly why it is so poorly soluble in water — the physical property behind its poor absorption. Plants store little free ellagic acid; it (and commercial supply) is obtained by hydrolysis/extraction from ellagitannin-rich sources — oak galls, pomegranate peel, chestnut, walnut, berries. Total synthesis is possible but not the practical route; extraction is cheaper and the molecule’s low solubility makes purification the real work.

Patents: not yet researched (future patent-loop pass).

Toxicity & Safety

As an ordinary dietary polyphenol from pomegranate, berries, walnuts and oak-aged foods, ellagic acid has a reassuring safety record at food levels and low intrinsic toxicity — a 90-day rat study fed up to 5% of the diet (tens of g/kg/day) with no deaths or treatment-related toxicity ^{19Reference 19Tasaki M et al. · 2008AnimalSafety assessment of ellagic acid, a food additive, in a subchronic toxicity study using F344 ratsView study →}, and it is an accepted food antioxidant in Japan. The honest caveat: this record is for food-level, mostly ellagitannin-bound intake; safety of concentrated isolated-ellagic-acid supplements taken chronically at high doses is limited (and its poor, saturable absorption means much of a large dose simply passes through unabsorbed rather than being “safely handled” systemically).

The interaction worth flagging is with anticoagulants. In a controlled animal study ellagic acid (like quercetin) showed pharmacodynamic and pharmacokinetic interaction with warfarin — prolonging INR and inhibiting the CYPs that clear it (CYP2C9, CYP2C8, CYP3A4) ^{20Reference 20Alnaqeeb M et al. · 2019AnimalCritical pharmacokinetic and pharmacodynamic drug-herb interactions in rats between warfarin and pomegranate peel or guava leaves extractsView study →}. This is animal/in-vitro, not proven in people, so hedge it — but the sensible advice is that anyone on warfarin or other anticoagulant/antiplatelet therapy treat high-dose ellagic acid or pomegranate-peel supplements as a potential additive bleeding-risk and CYP concern. As a polyphenol it can also bind non-heme iron in the gut, relevant to iron-deficiency.

Dosage

There is no evidence-based dose of isolated ellagic acid. The small pure-ellagic-acid metabolic trials used ~180–1,000 mg/day for 8–12 weeks ^{8,9Reference 8Hidalgo-Lozada GM et al. · 2022RCTEllagic acid effect on the components of metabolic syndrome, insulin sensitivity and insulin secretion — a randomised, double-blind, placebo-controlled clinical trialView study →Reference 9Ghadimi M et al. · 2021RCTDecreased insulin resistance in diabetic patients by influencing Sirtuin1 and Fetuin-A following supplementation with ellagic acid — a randomised controlled trialView study →}, and the urolithin-A muscle trials dose the metabolite at ~500–1,000 mg/day — not ellagic acid ^{5,6Reference 5Singh A et al. · 2022RCTUrolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomised trial in middle-aged adultsView study →Reference 6Liu S et al. · 2022RCTEffect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults — a randomised clinical trialView study →}. Dietary intake comes almost entirely as ellagitannins from pomegranate, berries and nuts, and how much reaches the body depends on your urolithin metabotype ^{13Reference 13Tomás-Barberán FA et al. · 2014Ellagic acid metabolism by human gut microbiota — consistent observation of three urolithin phenotypes in intervention trials, independent of food source, age and health statusView study →}.

These are descriptive research figures, not a recommendation — the pure-isolate evidence is small and preliminary, the muscle evidence is for a different molecule, and individual response is gated by the microbiome.

References