Green tea extract
Content by: OpenSupplement Editorial Team | Medical review: pending | Last updated: April 13, 2026
TL;DR
Concentrated antioxidant polyphenol from green tea leaves
Moderate evidence for boosting metabolism and fat oxidation
Moderate-to-low evidence for cognitive protection and liver health
Potential for liver toxicity at very high doses on an empty stomach
Inexpensive: ~$8-15/month
Best for: Metabolic support, general antioxidant defense
What it is
EGCG (Epigallocatechin gallate) is the most abundant and potent catechin in green tea. It is a powerful antioxidant that protects cells from oxidative damage. Mechanistically, EGCG inhibits an enzyme that breaks down norepinephrine, the hormone that tells fat cells to break down fat.
While drinking green tea is great, supplements provide a concentrated dose of EGCG (often equivalent to 5-10 cups of tea) to reach 'therapeutic' levels for metabolic or neuroprotective effects.
What the research says
EGCG is a popular but modest weight loss aid. Fat Oxidation. Clinical trials show that green tea extract can increase 24-hour energy expenditure and fat oxidation (burning). Weight Loss. A 2009 meta-analysis showed that green tea catechins significantly decreased body weight and helped maintain weight loss. Note. The effect is small—usually a few pounds over several months—and works best when combined with light caffeine. [1][2]
EGCG is a promising neuroprotective agent. The Amyloid Link. Lab studies show EGCG can prevent the misfolding of proteins associated with Alzheimer's. Evidence. Population studies show green tea drinkers have lower rates of cognitive decline, but clinical trials are still in early phases. It is best viewed as a 'brain healthy' habit rather than a treatment for memory loss.
This is a double-edged sword. Potential Benefit. In low doses, EGCG may reduce liver fat and inflammation. Risk. However, high doses of green tea extract (especially on an empty stomach) have been linked to rare but serious liver injury. Recommendation. Do not exceed 800mg of EGCG daily, and always take it with food. [3]
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Green tea extract on Amazon
Safety
Safe for most at standard doses. However, the 'concentrated' nature of extracts can be hard on the liver for some individuals. Crucial: Never take high-dose EGCG on an empty stomach. If you have any history of liver disease, consult a doctor first.
Interactions
- Stimulants: May increase heart rate or jitteriness when combined with other caffeine sources.
- Blood Thinners: May have a mild anti-clotting effect.
- Nadolol: Green tea can significantly reduce the absorption of this blood pressure medication.
Dosing
Standard Dose: 200-500 mg of EGCG daily. Timing: Take with food. Form: Look for 'decaffeinated' if you are sensitive to stimulants.
Cost
Affordable. $8-15 per month.
The bottom line
Green tea extract is a great 'foundational' antioxidant. It's not a magic weight loss pill, but it provides broad cellular protection and a small metabolic nudge.
References
- Phung OJ, Baker WL, Matthews LJ, Lanosa M, Thorne A, Coleman CI. Effect of green tea catechins with or without caffeine on anthropometric measures: a systematic review and meta-analysis. Am J Clin Nutr. 2010;91(1):73-81.
- Peng X, Zhou R, Wang B, Yu X, Yang X, Liu K, Mi M. Effect of green tea consumption on blood pressure: a meta-analysis of 13 randomized controlled trials. Sci Rep. 2014;4:6251.
- Sarma DN, Barrett ML, Chavez ML, et al. Safety of green tea extracts: a systematic review by the US Pharmacopeia. Drug Saf. 2008;31(6):469-484.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.