What does EGCG mean?

EGCG stands for epigallocatechin gallate — a polyphenol molecule with the formula C₂₂H₁₈O₁₁ and a molecular weight of 458.37 g/mol. It is the most abundant catechin in green tea, accounting for 50–80% of total catechin content, and it reaches its highest concentrations in matcha because you consume the whole leaf rather than a steeped infusion.

The name breaks down into its chemistry. “Epigallo” refers to the trihydroxyl group on the B ring. “Catechin” is the parent flavonoid class. “Gallate” means a gallic acid ester is bonded at the 3-position on the C ring. That gallic acid attachment is what separates EGCG from its less potent relatives — and why it dominates antioxidant research on tea.

What EGCG is at the molecular level

EGCG is the ester of epigallocatechin and gallic acid, classified as a flavan-3-ol within the broader polyphenol family. Its molecular formula is C₂₂H₁⁸O₁₁ — 22 carbon atoms, 18 hydrogen, 11 oxygen — with a molecular weight of 458.37 g/mol according to PubChem (CID 65064).

The structure has three rings that matter for its biological activity:

• B ring — carries three hydroxyl (-OH) groups in a pyrogallol arrangement. These donate hydrogen atoms to neutralize free radicals.
• C ring — bonded to a galloyl group (gallic acid ester) at the 3-position. This gallate moiety doubles the radical-scavenging capacity compared to ungallated catechins like EGC or EC.
• A ring — provides the flavonoid backbone and contributes to metal chelation at the 4-keto, 5-hydroxy positions.

That dual capacity — pyrogallol B ring plus gallate C ring — is why EGCG outperforms every other tea catechin in antioxidant assays. EGC has the B ring but lacks the gallate. ECG has the gallate but only two hydroxyls on the B ring. EGCG has both.

How EGCG works as an antioxidant

EGCG neutralizes free radicals through three distinct mechanisms: hydrogen atom transfer, electron donation, and transition metal chelation. A 2018 study in Molecules confirmed EGCG as the most effective catechin against oxidative stress via both hydrogen peroxide scavenging and direct radical quenching.

The hydroxyl groups on the B ring and the galloyl moiety on the C ring are the active sites. They donate hydrogen atoms to reactive oxygen species — superoxide, hydroxyl radicals, peroxyl radicals — stabilizing them before they can damage DNA, lipids, or proteins. Because EGCG has eight hydroxyl groups total (five on the B/gallate rings), it can neutralize multiple radicals per molecule.

EGCG also chelates free iron (Fe²⁺) and copper (Cu²⁺) ions at the 3′,4′-dihydroxy position on the B ring and the 4-keto, 5-hydroxy position on the C ring. By binding these metals, EGCG prevents Fenton reactions — the iron-catalyzed production of hydroxyl radicals that causes the most aggressive oxidative damage in cells.

Beyond direct scavenging, EGCG activates the body’s own antioxidant defenses. It upregulates the Nrf2 pathway, which triggers production of endogenous antioxidant enzymes like superoxide dismutase and glutathione peroxidase. This indirect mechanism may be more significant long-term than direct radical scavenging, because enzymatic defenses operate continuously rather than molecule-by-molecule.

EGCG concentration in matcha vs other teas

Matcha delivers substantially more EGCG per serving than brewed green tea because you ingest the entire ground leaf. The landmark comparison comes from Weiss and Anderton (2003), published in the Journal of Chromatography A, who measured catechins in matcha using micellar electrokinetic chromatography.

Their finding: matcha contained 137 times more EGCG than the specific bagged green tea they tested (Tazo China Green Tips). That number circulates widely, but context matters. The 137x figure compares matcha powder — where you consume the whole leaf — against a single brand of bagged tea steeped once. Against the broader literature on brewed green teas, Weiss and Anderton reported matcha had “at least three times” the EGCG of the highest previously published value.

The gap exists because brewing extracts only a fraction of the catechins locked inside the leaf cell walls. With matcha, you consume those cell walls directly. No extraction step, no waste.

The four catechins: where EGCG fits

Green tea contains four major catechins — EGCG, EGC, ECG, and EC — and EGCG typically accounts for 50–80% of total catechin content. The proportions shift depending on cultivar, growing conditions, and processing, but the hierarchy stays consistent: EGCG dominates.

Here is what a typical 1 g serving of matcha contains, based on the Weiss and Anderton (2003) analysis:

• EGCG (epigallocatechin gallate) — 30–35 mg. The gallated, trihydroxyl catechin. Strongest antioxidant activity.
• EGC (epigallocatechin) — ~41 mg. Same trihydroxyl B ring as EGCG but no gallate group. Second-most abundant.
• ECG (epicatechin gallate) — ~4 mg. Has the gallate but only a dihydroxyl B ring.
• EC (epicatechin) — ~10 mg. Simplest structure — no gallate, dihydroxyl B ring.

A counterintuitive detail: EGC is actually more abundant by mass in some matcha samples than EGCG. But EGCG gets the research attention because its dual structure (pyrogallol + gallate) gives it roughly twice the radical-scavenging activity of EGC in controlled assays. Quantity and potency are different questions.

Bioavailability: how much EGCG your body actually absorbs

Only about 16% of ingested EGCG reaches the bloodstream unchanged, with peak plasma concentration occurring 1.3–1.6 hours after consumption. That low absorption rate is the central limitation of EGCG as a dietary compound — and why dose and timing matter more than most people realize.

EGCG crosses the intestinal wall primarily through passive diffusion. No dedicated transport receptor has been identified for catechins, which means absorption depends on the molecule passively moving through or between intestinal cells. Once absorbed, 50–90% of circulating EGCG is conjugated into glucuronide metabolites, and the half-life is 2–4 hours.

Three factors determine how much EGCG you actually absorb:

1. Fasting state. A 2020 study in Antioxidants found that EGCG taken after overnight fasting produced the highest plasma concentration. Taking EGCG with a light breakfast reduced absorption by 2.7x; embedding it in food reduced it by 3.9x.
2. Stomach pH. EGCG is most stable at pH 3.5–4.5. The acidic environment of an empty stomach preserves the molecule. Above pH 5, EGCG loses a proton and begins oxidizing, reducing the amount available for intestinal absorption.
3. Dose timing. Because the half-life is short (2–4 hours), spacing multiple smaller servings across the day maintains more consistent plasma levels than a single large dose.

How shading and processing affect EGCG levels

Extended shade-growing — the defining step in matcha production — reduces overall catechin levels while increasing L-theanine and chlorophyll. The tradeoff is biochemical: sunlight converts L-theanine into catechins via photosynthesis, so blocking light preserves amino acids at the expense of polyphenols.

This creates a paradox. Ceremonial-grade matcha, grown under 3–4 weeks of shade, has higher L-theanine and lower bitterness but not necessarily more EGCG. A 2025 study in the Journal of Food Measurement and Characterization found culinary matcha averaged 26.10 ± 4.07 mg/g of EGCG, while ceremonial matcha averaged 21.76 ± 1.63 mg/g — though the difference was not statistically significant.

Grade and price are poor predictors of EGCG content. If your goal is maximum EGCG per gram, a well-made culinary matcha may match or exceed ceremonial grade.

Processing also matters. Matcha leaves are steamed within hours of harvest to halt oxidation, which preserves catechins. Black tea and oolong undergo deliberate oxidation that converts EGCG into theaflavins and thearubigins — different polyphenols with different (and generally weaker) antioxidant profiles. The steaming step is why green tea retains 3–5x more EGCG than oxidized teas from the same plant.

EGCG stability: heat, pH, and storage

EGCG degrades through oxidation, and the two biggest accelerants are alkaline pH and high temperature. A 2019 study in the Journal of Food Engineering found that pH had an even greater destabilizing effect than heat — EGCG breaks down faster in alkaline conditions at moderate temperature than in acidic conditions at high temperature.

The practical implications for matcha preparation:

• Temperature. At 80°C, EGCG steadily declines over time while its epimer (GCG) initially rises then also drops. Traditional matcha preparation at 70–80°C is a reasonable compromise: hot enough to suspend the powder, cool enough to limit significant degradation during the brief whisking window.
• pH. EGCG is most stable below pH 4.5. Matcha dissolved in water sits near pH 6–7, which is less than ideal but acceptable for immediate consumption. Adding lemon juice (pH ~2) may help preserve EGCG if you’re not drinking immediately.
• Storage. Light, oxygen, and humidity all accelerate oxidation. Sealed, opaque packaging stored in a cool environment preserves EGCG content. Once opened, matcha powder begins losing potency — use it within 4–6 weeks for peak catechin levels.
• Radiation. UV exposure destroys up to 85% of EGCG within one hour. Never store matcha in clear containers or direct sunlight.

Key research on EGCG and health

Three studies form the foundation of EGCG research relevant to matcha drinkers: Weiss & Anderton (2003) on concentration, Kuriyama (2006) on mortality, and Dietz (2017) on cognition. Each answers a different question, and each has important limitations.

Weiss & Anderton, 2003 — Published in the Journal of Chromatography A. Measured catechin content in matcha using micellar electrokinetic chromatography. Established that matcha contains at least 3x the EGCG of the highest previously reported green tea value. The 137x figure specifically compared matcha against a single bagged tea brand and does not generalize to all green teas.

Kuriyama et al., 2006 — Published in JAMA. Followed 40,530 Japanese adults (ages 40–79) for up to 11 years. Those drinking 5+ cups of green tea daily had 26% lower cardiovascular mortality compared to those drinking less than 1 cup daily. The association was stronger in women (31% lower CVD death risk). No significant link was found for cancer mortality. This was an observational cohort study — it shows correlation, not causation.

Dietz et al., 2017 — Published in Food Research International. A randomized, placebo-controlled trial with 23 participants testing 4 g of matcha on cognitive performance. Found only modest effects on attention speed and working memory at 60 minutes. A key limitation: EGCG reaches peak plasma concentration at 1.3–2.4 hours, meaning the testing window likely missed the compound’s peak activity.

For a deeper look at the health research, see our full guide on EGCG and antioxidants in matcha.

One detail that rarely appears in EGCG discussions: the European Food Safety Authority flagged a daily intake threshold of 800 mg of EGCG from supplements as potentially harmful to liver function. At 30–35 mg per gram of matcha, you would need to consume over 23 grams of matcha powder daily to approach that level — far beyond the 2–4 g typical serving range. Whole-food sources like matcha carry a margin of safety that isolated EGCG supplements do not, because the matrix of other catechins, L-theanine, and fiber moderates absorption rate. The molecule is potent. The delivery method decides whether that potency works for you or against you.