Green tea extract is rich in catechins, particularly epigallocatechin gallate (EGCG), which has been extensively studied for its thermogenic and fat-oxidation effects. Multiple meta-analyses confirm modest but consistent effects on weight loss and metabolic rate, especially when combined with caffeine. Green tea extract also provides antioxidant benefits and may support cardiovascular health.
How it works
EGCG inhibits catechol-O-methyltransferase (COMT), the enzyme that breaks down norepinephrine. This prolongs norepinephrine signalling, increasing thermogenesis (heat production) and fat oxidation. EGCG also activates AMPK, promoting glucose uptake into muscle cells and reducing fat storage. The caffeine content provides additional thermogenic effects via phosphodiesterase inhibition.
Evidence-based uses
Meta-analyses show green tea extract increases 24-hour energy expenditure by 80-100 kcal/day and fat oxidation by 16-17%. A Cochrane review of 14 RCTs found mean weight loss of 1.3kg over 12 weeks vs placebo. Most effective in those with low habitual caffeine intake. Choose decaffeinated extracts if sensitive to stimulants.
Safety
Green tea extract may reduce the effectiveness of warfarin by providing vitamin K. Monitor INR closely if combining.
EGCG can reduce absorption of nadolol by up to 85%. Take at least 4 hours apart from beta-blockers.
The caffeine in green tea extract may interact with MAOIs, potentially causing dangerous increases in blood pressure.
High-dose green tea extract (>800mg EGCG/day) has rare but documented cases of hepatotoxicity. Avoid with existing liver disease. Use lower doses and monitor liver function.
Compare prices
5 products compared across Australian retailers. Sorted by price per serve.
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| Product | Price | /serve | |
|---|---|---|---|
Best BulkSupplements Green Tea Extract Powder (50% EGCG) BulkSupplements | $32.96 | $0.07 | |
Now Foods EGCg Green Tea Extract 400mg iHerb | $29.99 | $0.17 | |
Jarrow Formulas Green Tea 500mg iHerb | $19.49 | $0.19 | |
Life Extension Mega Green Tea Extract (decaf) Life Extension | $34.50 | $0.35 | |
Thorne Green Tea Phytosome Thorne | $52.00 | $0.87 |
Prices in AUD. Some links are affiliate links — we may earn a commission at no extra cost to you.
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Green Tea Extract (EGCG) has 4 known interactions. Check if it's safe with your medications.
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This information is for educational purposes only and is not intended as medical advice. Always consult a healthcare professional before starting any supplement. Evidence ratings are based on peer-reviewed clinical research. Individual results may vary.