EGCG, short for epigallocatechin gallate, is the most abundant and biologically active antioxidant compound in green tea. It belongs to a family of plant chemicals called catechins, which are a type of flavanol found naturally in tea leaves. A single cup of sencha green tea contains anywhere from 25 to 250 mg of EGCG, depending on the quality of the leaves and how you brew it. This compound is the main reason green tea gets so much attention in health research.
How EGCG Works in Your Body
EGCG is a polyphenol, meaning it’s a plant compound with a structure that lets it interact with free radicals, the unstable molecules that damage cells and contribute to aging and disease. What makes EGCG more potent than other catechins in tea is its specific chemical structure: it has an extra chemical group attached to its core ring and additional oxygen-hydrogen clusters on another part of the molecule. These features give it a larger “surface area” for neutralizing free radicals.
At the concentrations you’d get from drinking tea, EGCG actually triggers a small, controlled burst of reactive oxygen species in your cells. That sounds counterintuitive, but this mild signal activates your body’s own protective pathways, essentially training your cells to defend themselves more effectively. It also interacts with receptors on cell surfaces and influences signaling pathways involved in inflammation and cell survival.
Effects on Metabolism and Fat Burning
One of the most studied effects of EGCG is its influence on energy expenditure. In a trial published in the American Journal of Clinical Nutrition, participants who took a green tea extract containing 90 mg of EGCG (plus 50 mg of caffeine) burned 4% more calories over a 24-hour period compared to a placebo group. That’s a modest but measurable bump.
More striking was the shift in where those calories came from. In the placebo group, fat burning accounted for about 32% of total energy expenditure. In the green tea group, that number jumped to nearly 42%. So EGCG doesn’t just increase how much energy you burn; it shifts the balance toward burning fat specifically. The effect works in combination with caffeine, and most research uses the two together, which is exactly what you get in a cup of green tea.
Cardiovascular and Blood Vessel Effects
EGCG stimulates the production of nitric oxide in blood vessel walls. Nitric oxide is a molecule that tells blood vessels to relax and widen, which lowers blood pressure and improves blood flow. Research in the American Journal of Physiology showed that EGCG triggers this relaxation through a specific enzyme pathway that also plays a role in insulin signaling, which may explain why green tea consumption is linked to improvements in both blood pressure and blood sugar regulation simultaneously.
Why Green Tea Has Far More Than Black Tea
Not all teas are equal when it comes to EGCG content. Green tea leads by a wide margin, with roughly 946 parts per million of EGCG in hot water extractions. White tea comes in second at about 715 ppm. Black tea trails far behind at just 109 ppm.
The difference comes down to processing. Green tea leaves are quickly heated after harvesting to prevent oxidation, which preserves the catechins. Black tea goes through full oxidation (fermentation), which converts most of the catechins into different compounds called theaflavins and thearubigins. These have their own benefits, but they’re not EGCG. If you’re specifically after EGCG, green tea is the clear choice, with white tea as a reasonable alternative.
How to Get More EGCG From Your Cup
EGCG extraction depends on both water temperature and steeping time. Research on brewing optimization found that EGCG is a “time and temperature dependent” compound, meaning you need both heat and duration to pull it out of the leaves. Higher temperatures extract more EGCG than cooler water, and longer steeping times continue to increase the concentration. For practical home brewing, using water around 80 to 85°C (175 to 185°F) and steeping for at least 3 to 5 minutes will give you a solid extraction without making the tea undrinkably bitter. Going hotter and longer pulls out more EGCG, but also more astringent compounds.
Your body’s ability to absorb EGCG also matters. Taking green tea or a green tea extract on an empty stomach results in more than 3.5 times the peak blood levels of free EGCG compared to taking it with food. The likely reason is that your stomach’s natural acidity (pH 1.1 to 1.6 when fasted) keeps EGCG stable, while the higher pH after a meal (5.8 to 6.7) causes it to degrade. Food also slows intestinal absorption through interactions with dietary fats, proteins, and bile acids. The tradeoff: taking concentrated green tea supplements on an empty stomach can cause mild nausea in some people, especially at higher doses.
Safety Limits and Liver Concerns
EGCG from brewed green tea is generally well tolerated, but concentrated supplements are a different story. Health Canada’s safety review identified 600 mg of EGCG per day as the threshold below which no adverse effects were observed in healthy people. After accounting for the EGCG you might already get from food and drinks (estimated at around 300 mg per day for regular tea drinkers), the recommended maximum from supplements is 300 mg of EGCG per day.
The main concern at high doses is liver injury. Cases of liver toxicity have been linked to green tea extract supplements, not to drinking tea itself. To reduce the risk, Health Canada also recommends limiting any single serving of a supplement to no more than 100 mg of EGCG, roughly the equivalent of one cup of green tea. If you’re drinking two or three cups of green tea a day, you’re well within safe ranges. Problems arise when people stack concentrated capsules on top of regular tea consumption.
Tea vs. Supplements
The wide range of EGCG in a cup of green tea (25 to 250 mg) means your actual intake depends heavily on the specific tea you buy, how much leaf you use, and how you brew it. High-quality loose leaf teas steeped in hot water for several minutes sit at the upper end. Bagged teas brewed quickly in lukewarm water sit at the lower end.
Supplements offer a more predictable dose, but they come with the absorption and safety considerations described above. Drinking green tea on a mostly empty stomach, brewed hot and steeped generously, is likely the simplest way to get a meaningful amount of EGCG without worrying about exceeding safe limits.