Antioxidant ·Moderate evidence ·Reviewed May 2026
EGCG is the most abundant and biologically active catechin in green tea (Camellia sinensis) and is sold as a standardized polyphenol extract for metabolic, cardiovascular, and antioxidant support. It is studied for modest effects on body weight, blood lipids, and vascular function, largely attributed to its potent free-radical-scavenging and enzyme-modulating activity. Because it is concentrated far above the levels found in brewed tea, supplemental EGCG carries dose-dependent safety considerations not seen with ordinary tea drinking.
The bottom line
Evidence rating moderate. Most-documented uses: provides potent antioxidant and free-radical scavenging activity, supports modest weight management and fat oxidation, especially with exercise, may improve blood lipid profile (total and ldl cholesterol). 9 sources indexed (1999–2018), with 5 interaction records on file.
Core mechanism
EGCG is a powerful direct antioxidant that scavenges reactive oxygen and nitrogen species and chelates pro-oxidant transition metals such as iron and copper, while also upregulating endogenous antioxidant defenses through activation of the Nrf2/ARE pathway. Metabolically, it inhibits catechol-O-methyltransferase (COMT), prolonging the action of norepinephrine and thereby supporting thermogenesis and fat oxidation, and it inhibits intestinal lipases and alpha-amylase to reduce dietary fat and carbohydrate absorption. EGCG also modulates AMPK signaling, suppresses lipogenic and inflammatory transcription factors (including NF-kB), and improves endothelial function by enhancing nitric oxide bioavailability. Its bioavailability is low and it undergoes extensive glucuronidation, sulfation, and methylation, which limits systemic exposure relative to ingested dose.1,7
EGCG is water-soluble with inherently low oral bioavailability. While fasting can increase peak plasma levels, concentrated EGCG taken on an empty stomach is associated with greater risk of liver injury, so authoritative guidance recommends taking it with food. Co-ingestion with vitamin C or piperine may modestly improve stability and absorption; calcium, iron, and milk proteins can reduce it.1,3
Ranked by evidence and value.
Real-world pricing across three quality tiers. Assumes Standardized decaffeinated green tea extract capsule.
Budget tier reflects bulk standardized green tea extract capsules (200 to 400 mg EGCG/dose); mid tier reflects branded decaffeinated, third-party-tested extracts; premium reflects phytosome / enhanced-absorption formulations sold at a lower effective milligram dose. Brewed green tea is comparable or cheaper per dose if buying loose-leaf or bagged tea. Prices are approximate US retail per effective daily EGCG dose. Updated 2026-06-04.
Dose: 200 to 400 mg EGCG/day, often paired with caffeine7
Timing: With or before meals; avoid late-day dosing if caffeinated
Effects on body weight and fat oxidation are modest and inconsistent across trials; benefit is largest when combined with caffeine and an exercise/diet program. Not a substitute for caloric control.
Dose: 200 to 400 mg EGCG/day3
Timing: Daily, with food
Green tea catechin intake is associated with small improvements in LDL cholesterol and blood pressure in meta-analyses; effect sizes are modest and benefit is most consistent from habitual tea consumption.
Dose: 100 to 300 mg EGCG/day
Timing: Spread across the day, with food
Whole-food tea sources are preferred for longevity-oriented daily use because they avoid the high single-dose hepatotoxicity risk seen with concentrated extracts. Human longevity benefit from isolated EGCG remains unproven.
Dose: 200 to 300 mg EGCG/day
Timing: Daily with food; not required to be peri-workout
Catechins may blunt exercise-induced oxidative stress markers, but evidence that this improves performance or hypertrophy adaptation is limited; very high antioxidant doses could theoretically interfere with training adaptations.
What to test, the optimal window inside the conventional range, and how long a response takes.
High-dose green tea extract/EGCG can occasionally raise ALT, signaling idiosyncratic hepatocellular injury; it is monitored to detect rather than to lower this marker.1,6
Baseline and periodic ALT is reasonable for those taking high-dose (greater than 800 mg/day) EGCG extracts or with prior liver issues. Discontinue and seek care if ALT rises above about 3 times the upper limit of normal or with jaundice, dark urine, or right-upper-quadrant pain.
Where this appears in the symptom-to-supplement map, ranked by relevance.
EGCG inhibits catechol-O-methyltransferase (COMT), which slows the breakdown of norepinephrine and modestly prolongs sympathetic stimulation of thermogenesis and fat oxidation. Effects on energy expenditure and body weight are small and most consistent when combined with caffeine.7,1
Weight-loss effect sizes are modest (often 1-2 kg over 12 weeks) and partly caffeine-dependent. High-dose EGCG taken on an empty stomach has been linked to rare hepatotoxicity; take with food and avoid exceeding roughly 800 mg/day.
Green tea catechins including EGCG reduce intestinal micellar solubilization and absorption of dietary cholesterol and may upregulate hepatic LDL-receptor activity, producing small reductions in total and LDL cholesterol in meta-analyses.7,1
Average LDL reductions are modest (roughly 0.1-0.2 mmol/L). Catechins can chelate non-heme iron and reduce its absorption, so separate from iron-rich meals or iron supplements.
EGCG is a potent direct radical scavenger and activates the Nrf2/ARE pathway, inducing endogenous antioxidant enzymes such as glutathione-S-transferase and heme oxygenase-1. At high concentrations it can paradoxically act as a pro-oxidant.1,6
Biomarker improvements are inconsistent across trials and clinically meaningful outcomes are not established. Pro-oxidant behavior at high doses argues against megadosing.
EGCG inhibits intestinal alpha-amylase and alpha-glucosidase and may improve insulin signaling and reduce glucose absorption, yielding small reductions in fasting glucose in some meta-analyses.1,2
Glycemic effects are small and inconsistent; not a substitute for glucose-lowering medication. Monitor if combined with antidiabetic drugs.
Green tea catechins such as EGCG bind non-heme iron in the gut and form poorly absorbed complexes, reducing iron absorption. This is most relevant for people with iron deficiency or anemia taking iron supplements.
Recommendation: Separate EGCG (or green tea extract) and iron supplements by at least 2 hours. Take iron with vitamin C and away from catechin-rich products to preserve absorption.
EGCG is the principal catechin in green tea extract, so combining a standalone EGCG product with green tea extract stacks the same compound and substantially raises total EGCG exposure.
Recommendation: Do not stack standalone EGCG with green tea extract. Count both toward total daily EGCG and keep the combined dose well below roughly 800 mg/day, taken with food.
EGCG and curcumin both activate the Nrf2 antioxidant pathway and inhibit NF-kB-driven inflammatory signaling, providing complementary antioxidant and anti-inflammatory actions in preclinical models.
Recommendation: Reasonable to combine for antioxidant/anti-inflammatory support. Take both with food; clinical benefit of the combination in humans is not established.
Quercetin inhibits the metabolism of EGCG, including COMT-mediated methylation and efflux transport, which can increase EGCG bioavailability and prolong its activity; both are also complementary antioxidant flavonoids.
Recommendation: Pairing is reasonable and may modestly enhance EGCG levels. Take with food and avoid high combined doses on an empty stomach to limit GI and hepatic risk.
High-dose EGCG can be hepatotoxic in susceptible individuals. NAC is hepatoprotective (a glutathione precursor and the antidote for acetaminophen toxicity), so co-use is not harmful, but stacking multiple high-dose polyphenols and supplements complicates monitoring of liver-related effects.
Recommendation: Use sensible EGCG doses with food. NAC is not contraindicated and may even be protective; watch for signs of liver stress (nausea, dark urine, jaundice) and check liver enzymes if using high-dose EGCG long term.
Search all 5 interaction records for EGCG (Epigallocatechin Gallate) →
Numbered references. Citations throughout the page link here.
Doses of EGCG at or above 800 mg/day from supplements were associated with statistically significant increases in serum transaminases, signaling potential liver injury.
Green tea consumption was associated with favorable reductions in blood pressure and LDL cholesterol, suggesting a cardiovascular benefit, though long-term outcome data were limited.
Green tea consumption significantly reduced total cholesterol and LDL cholesterol compared with control, with no significant effect on HDL cholesterol.
Green tea catechin-caffeine mixtures significantly reduced body weight and helped maintain weight after a period of weight loss, with effects modulated by habitual caffeine intake.
A green tea extract increased 24-hour energy expenditure and fat oxidation beyond what could be attributed to its caffeine content alone.
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