Named Bioactive Compounds · Compound
Ellagitannin (Tannin)
Moderate Evidencebotanical3 PubMed Studies
Hermetica Superfood Encyclopedia
Ellagitannins are polyphenolic compounds found in berries and pomegranates that convert to urolithin metabolites in the gut. These metabolites demonstrate anti-inflammatory properties through NF-κB pathway modulation and may support digestive and prostate health.
Ellagitannins are hydrolyzable tannins characterized by hexahydroxydiphenoyl units esterified to glucose cores, found naturally in pomegranates, berries (black raspberries, strawberries), walnuts, and oak-aged wines. They occur primarily in fruits, bark, and leaves, extracted using methanol or ethanol solvents, though clinical products typically use whole food matrices like pomegranate juice or standardized berry extracts.
Clinical evidence is limited to small intervention studies, with no large-scale RCTs or meta-analyses identified. Key trials include an IBD study (NCT03000101, n=80) testing pomegranate juice, a Phase I/II prostate cancer trial (PMID: 32112501, n=40) with black raspberry, and a microbiota study (PMID: 26189645, n=20) using pomegranate extract.
Clinically studied doses range from 1-2g/day ellagitannins via food matrices: 250mL/day pomegranate juice (~1g ellagitannins) for 12 weeks, 10-20g/day standardized black raspberry powder (5-10% ellagitannins) for 4 weeks, or 1000mg/day pomegranate extract for 4 weeks. No isolated forms tested; studies emphasize whole-food standardization. Consult a healthcare provider before starting any new supplement.
Ellagitannins are high-molecular-weight polyphenolic compounds (typically 300–4,000+ Da) belonging to the hydrolyzable tannin subclass. They are not a source of macronutrients (negligible protein, fat, carbohydrate contribution) but serve as bioactive secondary plant metabolites. Key chemical features: esters of hexahydroxydiphenic acid (HHDP) with a glucose core. Major individual ellagitannins include punicalagin (pomegranate, up to ~2,000 mg/L in juice), pedunculagin, casuarictin, sanguiin H-6 (raspberries, ~50–80 mg/100 g fresh weight), lambertianin C (blackberries), and vescalagin/castalagin (oak-aged wines, ~10–50 mg/L). Dietary concentrations vary significantly by source: pomegranate juice provides ~1,500–2,500 mg/L total ellagitannins; strawberries ~20–80 mg/100 g FW; raspberries ~150–300 mg/100 g FW; blackberries ~50–150 mg/100 g FW; walnuts ~60–90 mg/100 g; muscadine grapes ~30–70 mg/100 g FW. Upon hydrolysis in the gut (pH-dependent, enzymatic), ellagitannins release ellagic acid, which is further metabolized by gut microbiota (primarily Gordonibacter urolithinfaciens and Ellagibacter isourolithinifaciens) into urolithins (urolithin A, B, C, D), the principal circulating bioactive metabolites. Bioavailability of intact ellagitannins is extremely low (<1% absorption in the upper GI tract) due to high molecular weight and polarity. Ellagic acid absorption is also limited (~<5%). However, urolithins are well absorbed, reaching plasma concentrations of ~0.5–18 µM (urolithin A glucuronide being the dominant circulating form), with a Tmax of 24–48 hours post-ingestion and elimination half-life of ~17–24 hours. Approximately 40% of the population are 'metabotype A' (producing primarily urolithin A), ~10% are 'metabotype B' (producing urolithins A, B, and isourolithin A), and ~50% produce little to no urolithins ('metabotype 0'). Ellagitannins exhibit strong metal-chelating capacity (particularly Fe²⁺, Cu²⁺), high antioxidant capacity (ORAC values ~2–4× higher than simple phenolics per mole), and notable protein-binding affinity. They contain no significant vitamins or minerals themselves but may influence mineral bioavailability by chelating iron and other divalent cations in the gut lumen, potentially reducing non-heme iron absorption by ~20–50% when consumed concurrently with meals.
Ellagitannins are metabolized by gut bacteria into urolithin A and B, which inhibit nuclear factor-κB (NF-κB) signaling pathways. These urolithin metabolites reduce pro-inflammatory cytokines including TNF-α and IL-6 while modulating immune cell activation. The bioavailability depends on individual gut microbiome composition and ellagitannin-metabolizing bacteria.
A small trial (n=80) testing pomegranate juice in IBD patients showed preliminary benefits for inflammatory bowel disease management, though specific outcomes were not quantified. A Phase I/II dose-escalation study (n=40) with black raspberry demonstrated dose-dependent urolithin metabolite formation, indicating successful conversion of ellagitannins. Current evidence remains preliminary with small sample sizes and limited control groups. Larger randomized controlled trials are needed to establish therapeutic efficacy.
Ellagitannins from food sources are generally well-tolerated with minimal reported side effects. High doses may cause gastrointestinal upset including nausea or stomach discomfort in sensitive individuals. No significant drug interactions have been documented, though theoretical interactions with blood-thinning medications are possible due to polyphenolic activity. Safety during pregnancy and lactation has not been established through clinical studies.
