Catechin

Catechin is a flavonoid polyphenol (flavan-3-ol) with molecular formula C15H14O6 and molecular weight 290.27 g/mol. It is not a macronutrient or micronutrient source but a bioactive phytochemical compound. Key structural variants include (+)-catechin (most abundant natural form), (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin (EGC). Concentrations vary by source: green tea contains 100–300 mg catechins per 200 mL serving (predominantly EGCG at 50–80% of total catechins); dark chocolate provides 40–120 mg per 40 g serving; red wine contributes 20–60 mg per 150 mL; apples supply 8–30 mg per 100 g (skin-concentrated). Pure catechin contains no protein, fat, fiber, or caloric macronutrients. Bioavailability is characteristically low and variable: oral bioavailability is estimated at 1–12% due to extensive first-pass metabolism, intestinal efflux transport (P-glycoprotein), and gut microbiome-mediated catabolism into ring-fission metabolites (phenylvalerolactones, phenylpropionic acids). Peak plasma concentration (Cmax) of ~0.1–0.5 µmol/L is achieved approximately 1–2 hours post-ingestion for (+)-catechin. Bioavailability is enhanced by co-consumption with piperine (+20%), vitamin C (reduces oxidative degradation), and lipid-containing meals. It is moderately stable at acidic gastric pH but degrades rapidly above pH 7. Protein binding in plasma is approximately 80–90%, primarily to albumin. Half-life is approximately 2–4 hours. No vitamins or minerals are intrinsic to the isolated compound.