Green Tea Extract
Also known as: Camellia sinensis extract, EGCG, Green tea catechins
EGCG inhibits catechol-O-methyltransferase (COMT), prolonging catecholamine-driven thermogenesis. Meta-analyses show modest weight and fat-oxidation effects, largely caffeine-dependent. High-dose EGCG fasted has been linked to rare liver injury, prompting dose warnings in the EU.
Last reviewed: 2026-10-06 · 0 indexed studies
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Overview
Green tea extract is standardised for catechins, principally EGCG. It is one of the most common fat-burner ingredients: human trials show small increases in energy expenditure and fat oxidation, amplified by caffeine, with rare hepatotoxicity at high doses on an empty stomach.
Mechanism & Function
Mechanism of Action
COMT inhibition extends noradrenaline signalling, raising energy expenditure and fat oxidation; antioxidant effects are well characterised in vitro.
Physiological Role
No physiological role; a source of catechins and (usually) caffeine.
Primary Pathways
Performance / Health Relevance
Small acute fat-oxidation increases during exercise; not a meaningful ergogenic.
Evidence Review
No human clinical studies indexed for this ingredient yet.
No meta-analyses or systematic reviews indexed for this ingredient yet.
Dimensions marked N/A have no indexed evidence of that class. They are shown as unavailable rather than scored.
Practical Use & Dosage
- Minimum Effective Dose
- ~300–400 mg catechins/day
- Optimal Range
- 400–600 mg catechins/day (with meals)
- Upper / Caution Level
- EGCG ≥800 mg/day fasted linked to rare liver injury — take with food and respect label limits
- Timing
- With meals (never fasted at high doses)
- Best Format
- Extract standardised for EGCG/catechin content (e.g. 40–50% polyphenols)
- Bioavailability
- EGCG bioavailability is low and food-dependent; fasting raises exposure but also liver risk.
- Absorption Considerations
- Check caffeine content if sensitive.
Safety & Interactions
Side Effects
- •Rare hepatotoxicity at high fasted doses
- •Caffeine-related effects
- •GI upset
Contraindications
- Liver disease
- Fasting use of high-dose extracts
Drug Interactions
- •Stimulants (additive caffeine)
- •Certain chemotherapy drugs (bortezomib — EGCG may reduce efficacy)
Who Should Avoid
- •People with liver conditions
- •People combining multiple stimulant products
Monitoring
Take with food; discontinue if signs of liver injury appear.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Green Tea Extract typically used or indicated?
Green Tea Extract is most commonly used for: Fat-burner formulas, Antioxidant supplements, Metabolism-support blends. No physiological role; a source of catechins and (usually) caffeine.
How does Green Tea Extract work?
COMT inhibition extends noradrenaline signalling, raising energy expenditure and fat oxidation; antioxidant effects are well characterised in vitro.
What is the recommended dose of Green Tea Extract?
The optimal range is 400–600 mg catechins/day (with meals). with a minimum effective dose of ~300–400 mg catechins/day. Best taken: With meals (never fasted at high doses). Upper / caution level: EGCG ≥800 mg/day fasted linked to rare liver injury — take with food and respect label limits.
What are the side effects of Green Tea Extract?
Reported side effects include: Rare hepatotoxicity at high fasted doses; Caffeine-related effects; and GI upset. Monitoring: Take with food; discontinue if signs of liver injury appear.
Does Green Tea Extract interact with medications?
Known or theoretical interactions: Stimulants (additive caffeine); and Certain chemotherapy drugs (bortezomib — EGCG may reduce efficacy). Always check with a clinician before combining with prescription medication.
Who should avoid Green Tea Extract?
Green Tea Extract is generally not recommended for: People with liver conditions; People combining multiple stimulant products; Liver disease; and Fasting use of high-dose extracts.
How strong is the evidence for Green Tea Extract?
Evidence level: Limited (overall score 40/100), based on 0 indexed studies on SuppIndex.
Research & References (0)
No studies match this filter
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Research Overview
Limited EvidenceCite this ingredient
One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.
Stable URL
https://thesuppindex.com/ingredients/green-tea-extract
SuppIndex. (2026). Green Tea Extract: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/green-tea-extract
Based on 0 indexed studies · Evidence level: Limited.
Goal Ratings
Stack Compatibility
Core thermogenic-stack ingredient with caffeine and cayenne.