Named Bioactive Compounds · Compound
Tannic acid
Moderate Evidencepolyphenol
Hermetica Superfood Encyclopedia
Tannic acid is a polyphenolic compound that binds strongly to proteins through hydrogen bonding and hydrophobic interactions. Upon hydrolysis, it releases gallic acid and ellagic acid, which may contribute to antioxidant activity.
Tannic acid is a polyphenolic compound extracted from plant tissues rich in tannins, particularly from sumac leaves (Rhus species), oak gall-nuts (containing 75-80% tannin), grape pomace, and brown algae. Modern extraction methods include microwave-assisted and deep eutectic solvent techniques, achieving yields of 189.6-229.6 mg catechin equivalents per gram of biomass.
The research dossier contains no clinical trials, randomized controlled trials, or meta-analyses with PMIDs. All available studies focus on extraction methodology and chemical characterization rather than therapeutic effects or human health outcomes.
No clinically studied dosage ranges are available in the provided research. Extraction yields are measured in laboratory settings as 11.6-229.6 mg catechin equivalents per gram depending on extraction method, but human dosage recommendations are not established. Consult a healthcare provider before starting any new supplement.
Tannic acid (C₇₆H₅₂O₄₆, MW ~1701 g/mol) is a high-molecular-weight polyphenolic compound, not a nutrient per se but a bioactive plant secondary metabolite. It is a specific form of hydrolyzable tannin consisting of a central glucose core esterified with 8–10 gallic acid (3,4,5-trihydroxybenzoic acid) units. Key compositional details: • Gallic acid content upon complete hydrolysis: ~70–75% by weight (yields approximately 8–10 mol gallic acid per mol tannic acid) • Glucose core: ~10% by weight (1 mol per mol tannic acid) • Ellagic acid: formed via oxidative coupling of galloyl groups during partial hydrolysis, variable yield (~2–5% of hydrolysis products) • Total phenolic content: extremely high, typically >85% gallic acid equivalents (GAE) by Folin-Ciocalteu assay • No significant vitamin, mineral, fiber, or protein content — it is a pure polyphenolic compound • Caloric value: negligible at physiologically relevant doses. Bioavailability notes: Oral bioavailability of intact tannic acid is very low due to its large molecular size (>1700 Da), strong protein-binding affinity, and poor intestinal absorption. In the GI tract, it is partially hydrolyzed by esterases and gut microbiota to release gallic acid and pyrogallol, which are the primary absorbable metabolites. Tannic acid is a potent chelator of divalent metal ions (Fe²⁺, Zn²⁺, Ca²⁺), significantly reducing the bioavailability of dietary iron (up to 60–90% inhibition of non-heme iron absorption at doses of 25–100 mg) and other minerals when co-ingested. It also forms insoluble complexes with dietary proteins (proline-rich proteins particularly), reducing protein digestibility. Typical concentrations in natural sources: tea (Camellia sinensis) contains 2–7% tannic acid by dry weight; oak bark 8–20%; sumac fruits 4–25%; persimmon (unripe) 1–3%. Commercial tannic acid is typically ≥95% purity derived from Rhus semialata (Chinese gallnut) or Quercus infectoria (Aleppo oak gall).
Tannic acid exerts biological effects through protein precipitation via hydrogen bonding between its multiple phenolic hydroxyl groups and protein amino groups. The compound undergoes hydrolysis to release gallic acid and ellagic acid, which may scavenge free radicals through electron donation. Its protein-binding capacity affects enzyme activity and cellular membrane permeability.
Current research on tannic acid focuses primarily on extraction methodologies rather than clinical health outcomes. No controlled human trials have documented specific therapeutic benefits. Traditional industrial applications in leather tanning demonstrate its protein-binding properties, but this evidence cannot be extrapolated to health benefits. The released metabolites gallic acid and ellagic acid have separate research profiles, but tannic acid itself lacks clinical validation.
Tannic acid can cause gastrointestinal irritation, nausea, and constipation when consumed in large amounts. Its protein-binding properties may interfere with nutrient absorption and drug bioavailability, particularly affecting iron and other minerals. High doses may cause liver toxicity due to the formation of reactive metabolites. Pregnant and breastfeeding women should avoid supplemental tannic acid due to insufficient safety data.
