What Is EGCG?
Green tea (Camellia sinensis) contains a group of polyphenols called catechins. The most active and best-studied among them is epigallocatechin-3-gallate, or EGCG. EGCG accounts for up to 60% of total catechin content in green tea and is responsible for the majority of its documented health benefits.
EGCG's Primary Mechanisms of Action
Antioxidant Protection
EGCG is an exceptionally potent antioxidant — its ORAC (oxygen radical absorbance capacity) value is many times higher than that of vitamins C and E (Frei & Higdon, 2003). It neutralises free radicals through multiple pathways simultaneously, offering broad-spectrum protection against oxidative damage.
Fat Metabolism and Weight Management
EGCG inhibits the enzyme catechol-O-methyltransferase (COMT), which breaks down noradrenaline. This maintains elevated noradrenaline levels for longer, stimulating thermogenesis — heat production through fat tissue combustion (Dulloo et al., 1999). A meta-analysis of 11 studies found that green tea catechins combined with caffeine reduced body weight and improved weight maintenance compared to placebo (Hursel et al., 2009).
Cognitive Effects
EGCG influences several neurotransmitter systems in the brain. Research shows it improves spatial memory and reduces anxiety, in part by acting on GABA receptors (Unno et al., 2017). The combination of green tea's L-theanine, EGCG and caffeine represents a well-established cognitive synergy.
Supplement vs. Beverage
| Aspect | Green Tea Drink | EGCG Extract |
|---|---|---|
| EGCG per serving | 50–100 mg per cup | 200–400 mg per capsule |
| Caffeine | Yes | Minimal (decaffeinated) |
| Bioavailability | Moderate | Moderate (product-dependent) |
| Dosing precision | Limited | Exact |
If you want EGCG without multiplying your daily cup count, an extract offers greater flexibility.
Products Available in Estonia
OstroVit Green Tea Extract€10.90 In stock 100g is a pure green tea extract in powder form, easily added to a drink. OstroVit CLA + Green Tea + L-Carnitine 90 caps combines green tea's fat-burning properties with CLA and L-carnitine — a popular combination for body-composition support. Both are available at maxfit.ee in the fat burners category.
Dosage and Safety
Clinical studies typically used EGCG in the range of 200–800 mg per day. Many products standardise to 45–50% EGCG of total catechin content.
Caution: Very high doses (above 800 mg per day) may burden the liver, particularly on an empty stomach. The European Food Safety Authority (EFSA) advises caution above 800 mg/day. A prudent range is 200–400 mg per day.
Key interactions:
- Iron supplements — do not take simultaneously; EGCG reduces iron absorption
- Anticoagulants — consult a physician
- Caffeine supplements — cumulative stimulant effect
References
- Frei, B., & Higdon, J. V. (2003). Antioxidant activity of tea polyphenols in vivo: evidence from animal studies. Journal of Nutrition, 133(10), 3275S–3284S.
- Dulloo, A. G., et al. (1999). Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. American Journal of Clinical Nutrition, 70(6), 1040–1045.
- Hursel, R., Viechtbauer, W., & Westerterp-Plantenga, M. S. (2009). The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity, 33(9), 956–961.
- Unno, K., et al. (2017). Stress-reducing function of matcha green tea in animal experiments and clinical trials. Nutrients, 10(10), 1468.
- Khan, N., & Mukhtar, H. (2013). Tea and health: studies in humans. Current Pharmaceutical Design, 19(34), 6141–6147.
FAQ
Is EGCG extract more effective than drinking green tea?
EGCG extract allows precise dosing and is typically caffeine-free, which is an advantage for evening use or caffeine-sensitive individuals. Green tea itself is also beneficial, but EGCG quantities per cup are smaller and variable.
Can EGCG be taken on an empty stomach?
Generally not recommended — it may cause nausea. Take with a meal for best tolerance.
Is green tea extract suitable for athletes?
Yes, especially during a fat-loss phase. EGCG combined with caffeine is one of the few well-supported combinations for improving fat oxidation during exercise. It does not replace a calorie-controlled diet and consistent training, however.
