Epigallocatechin gallate (EGCG)

Epigallocatechin gallate, or EGCG, is a polyphenol and a member of the flavans. Chemically it is an ester of the catechin epigallocatechin with gallic acid. The tea plant, Camellia sinensis, makes it, and the European Food Safety Authority (EFSA) calls it the most relevant catechin in green tea.

Green tea is made without fermentation, so its catechins are not oxidized. EGCG belongs to the same family of tea compounds as catechin and epicatechin.

Black tea is made differently. During fermentation, enzymes oxidize the four main tea catechins into pigments such as theaflavins. Almost 60% of the solids in a black tea infusion are still uncharacterized, according to a 2020 review.

In USDA data, a cup of green tea (245 g) holds 172 mg of EGCG. Cranberries, the next-best food per cup, hold 0.97 mg.

Most readers do not know that EGCG is both a supplement and a drug ingredient. A green tea extract ointment, sinecatechins (sold as Veregen), carries a US Food and Drug Administration label for genital warts.

At the other end of the dose range, EFSA found that EGCG supplements of 800 mg a day or more raised liver enzymes in trials. Both stories are below, with the studies behind them.

Health benefits of EGCG

• ★★Little or no weight loss from green teaIn six trials outside Japan, green tea preparations changed weight by only 0.04 kg versus control, too small to tell from chance. A pooled review of catechins plus caffeine called the effect modest at best.
• ★★Slightly lower blood pressure from green teaIn 13 trials of green tea or extracts, the top blood pressure number fell by about 2 points (2.08 mm Hg). The bottom number fell by about 2 points (1.71 mm Hg).
• ★★Slightly lower LDL cholesterolIn 14 trials of green tea drinks and extracts, LDL (“bad”) cholesterol fell by 2.19 mg/dL. In 20 trials of catechins (all together, not EGCG alone), LDL fell by 5.30 mg/dL.
• ★★Slightly lower fasting blood sugarIn 17 trials, green tea lowered fasting glucose a little (0.09 mmol/L) and HbA1c, average blood sugar, by 0.30%. In 22 trials of catechins, fasting glucose fell by 1.48 mg/dL, but insulin and HbA1c did not change.
• ★★Higher liver enzymes at 843 mg a dayIn 1,075 postmenopausal women, a year of green tea extract (843 mg EGCG a day) raised liver enzyme ALT in 6.7%, against 0.7% on placebo. A review of 34 trials of green tea extract found liver events rare and mostly mild.

Foods high in EGCG

Green tea is the only common food with a large amount of EGCG. In USDA data it has 172 mg per cup (245 g) and 70.2 mg per 100 g.

Everything else on the list is far lower. Per 100 g, pecans hold 2.3 mg, hazelnuts 1.06 mg and cranberries 0.97 mg, followed by raspberries, plums and pistachios. An ounce of pecans (0.65 mg) has less than 1% of the EGCG in a cup of green tea.

How the tea is made and brewed matters. Green tea is not fermented, which keeps its catechins from oxidizing, while black tea fermentation turns them into other pigments.

In one study of Turkish green tea, EGCG peaked at 50.69 mg per 100 ml after 3 minutes of brewing at 85 °C. It fell with longer brewing. So a generic cup in the USDA data is only a guide.

How EGCG works

Most of what we know about how EGCG works comes from test tubes and cells. The amounts used there are often higher than what reaches the blood.

Researchers keep coming back to four ideas. It binds a receptor on the cell surface, and it blocks an enzyme that tags DNA. It can make hydrogen peroxide in a dish, and very little of it is absorbed. Here is each one, and what has been seen in people.

It sticks to a receptor on the cell surface

In 2004 a Japanese team reported that EGCG binds the 67-kDa laminin receptor, a protein on the surface of many cancer cells. The binding was strong (a nanomolar dissociation constant). Cells that made more of the receptor responded to EGCG at concentrations the authors call physiologically relevant.

A follow-up found that, through this receptor and a protein called eEF1A, EGCG switches on an enzyme called myosin phosphatase. Silencing any of the three in tumor cells removed EGCG’s tumor-slowing effect in animals. These are cell and animal findings, and none of the human trials above tested this route.

It can block an enzyme that tags DNA

DNA methyltransferase (DNMT) adds methyl tags to DNA that can switch genes off. Some cancers silence protective genes this way. In a test tube, EGCG blocked DNMT with a Ki of 6.89 µM. In esophageal cancer cells, 5 to 50 µM of EGCG reversed the silencing of four genes.

How do those amounts compare with the blood? Healthy men took single doses of 50 to 1,600 mg of purified EGCG on an empty stomach. Peak blood levels of total EGCG ranged from 130 to 3,392 ng/mL. We converted that to 0.28 to 7.4 µM, using EGCG’s molecular weight of 458.4 g/mol.

Only the top of that range came near the level that blocked the enzyme, and the dish tests went up to about seven times higher. The authors of another trial note that human blood levels are many times lower than the effective levels in test systems.

In a dish, it can make its own hydrogen peroxide

In some cell experiments, EGCG reacts with the culture medium and forms hydrogen peroxide, and the peroxide does much of the damage. In hamster ovary cells, the toxicity of EGCG differed between seven common media. Catalase, an enzyme that breaks down peroxide, cut it substantially.

A 2010 review says tea catechins are chemical antioxidants, but that some of their effects may come from adding oxidative stress. That stress seems to drive cell death in tumor cells, and may also switch on the body’s own defenses in normal tissue. So “antioxidant” is only part of the story, and some dish results may not carry over to the body.

Very little reaches the blood, and food changes how much

In people, EGCG is absorbed in small amounts, and the timing of a dose matters. In a crossover study of 30 healthy volunteers, peak free EGCG in blood was more than 3.5 times higher fasting than with a light breakfast. EFSA’s review agrees that a fasting bolus raises exposure compared with food or split doses.

Protein lowers it. In 24 women, drinking green tea extract with milk, caseinate or soy protein lowered EGCG blood exposure to 63 to 76% of the control.

Much of the EGCG in tea is also lost in the gut. In a lab test that mimicked stomach and small-intestine digestion, 10% or less of the EGCG in green tea survived. Adding 30 mg of vitamin C to 250 mL of tea left 54%, and citrus juices left 56 to 76%. This was a test-tube model, not people.

What has been seen in people

These effects are much easier to show in a dish than in a person. Trials of green tea extracts with 300 to 857 mg of EGCG a day moved LDL cholesterol and blood pressure by small amounts. The weight results are close to zero outside Japan.

EGCG did not slow multiple sclerosis on MRI and did not lower prostate cancer cases in the trials above. The one clear success, sinecatechins ointment on warts, is a defined extract used on skin, not a pill. Both the benefits and the liver warnings are on the study cards above.

Is EGCG safe? Supplements, dose and interactions

Green tea brewed the usual way is not a safety concern in EFSA’s 2018 opinion. The agency judged traditionally prepared infusions safe at the intakes seen in Europe. The average there is 90 to 300 mg of EGCG a day, and heavy drinkers reach up to 866 mg. EFSA noted rare, probably idiosyncratic (individual) liver injury.

Extracts are a different case. EFSA found that doses of 800 mg of EGCG a day or more from supplements clearly raised liver enzymes (transaminases) compared with control. It concluded that no EGCG dose from green tea extracts could be called safe.

• Liver enzymes in trials. The largest trial (843 mg a day for a year) raised ALT in 6.7% of women against 0.7% on placebo. A multiple sclerosis trial using 800 mg a day was stopped when 5 of 7 people on it had abnormal liver tests. EFSA saw no evidence of liver toxicity in trials below 800 mg a day for up to 12 months. But liver toxicity was reported with one product (an 80% ethanolic extract) at 375 mg, so the product matters. A review of 34 trials found liver events rare.
• Case reports and labels. EFSA found 22 reports in which green tea was the only suspected cause, and none was fatal. 8 came after tea infusions, and most after supplements. Most cases resolved after stopping. A US Pharmacopeia review linked injury to EGCG intakes of 140 mg to about 1000 mg a day. Its label text for green tea extract says to avoid it with a liver problem. It also says to stop if you notice abdominal pain, dark urine or yellow skin or eyes.
• Empty stomach. Peak EGCG in blood was more than 3.5 times higher fasting, and the same USP label tells people to take extract with food. In dogs, a green tea extract given fasted caused illness and deaths at high doses. Dosing with food gave much lower exposure.
• Medicines, pregnancy and skin. A single dose of EGCG-rich extract lowered blood levels of the beta-blocker nadolol to 0.72 and 0.60 of normal. Drinking green tea (700 ml a day for 14 days) cut its peak blood level by 85.3%, so ask your pharmacist if you take it. EFSA noted that none of the trials covered pregnant women, breastfed infants or children. In phase 3 trials, the sinecatechins ointment caused redness in 70%, itching in 69% and burning in 67% of users. Its label says not to use it on warts inside the urethra, vagina, cervix, rectum or anus.

How to get more EGCG

• Best food. Green tea, at 172 mg a cup and 70.2 mg per 100 g in USDA data. No other food has more than 2.3 mg per 100 g, so nuts and fruit add little.
• Brew and pair it well. In one study of Turkish green tea, EGCG peaked at 85 °C and 3 minutes of brewing. In a lab digestion test, citrus juice left 56 to 76% of the EGCG, against 10% or less in plain tea. But milk or protein lowered EGCG absorption in women.
• Tea versus extract. Trial doses of 800 mg equal about 4.7 cups of the USDA green tea figure. Yet EFSA found no sign of raised ALT at 5 cups a day or 700 mg of EGCG from infusions, though the data were sparse. The liver signal comes mostly from concentrated extracts, and fasting doses raise exposure. So if you use one, take it with food.

Frequently asked questions about EGCG

What does EGCG do for the body?

The measured effects are small, and none reaches strong evidence. In meta-analyses of green tea and catechins, LDL cholesterol was 2 to 5 mg/dL lower, roughly. Systolic blood pressure was about 2 mm Hg lower and fasting glucose slightly lower. As an ointment (sinecatechins), a green tea extract cleared genital warts in 57.2% of people against 33.7% on a plain ointment. Most trials used extracts with 300 to 857 mg of EGCG a day, not tea.

Which foods are high in EGCG?

Green tea is the main one by a wide margin. USDA data list 172 mg per cup (245 g) and 70.2 mg per 100 g. The next foods are pecans at 2.3 mg per 100 g, hazelnuts at 1.06 mg and cranberries at 0.97 mg. So green tea has about 30 times more than pecans per 100 g.

How much EGCG should you take a day?

No dose is proven best. Trials used 300 to 857 mg of EGCG a day from extracts, and the largest trial used 843 mg a day for a year. EFSA saw raised liver enzymes at 800 mg a day or more from supplements, and could not name a safe dose for extracts. Traditionally brewed green tea gives most people 90 to 300 mg a day, which EFSA considers safe.

Can EGCG damage the liver?

Rarely, and almost always with concentrated extracts. In the Minnesota Green Tea Trial, 843 mg a day for a year raised ALT in 6.7% of women against 0.7% on placebo. EFSA counted 22 case reports with green tea as the only suspected cause, and most resolved after stopping. See a doctor if you have abdominal pain, dark urine or yellowing of the skin or eyes.

Does EGCG help with weight loss?

Probably not by an amount that matters. Cochrane’s review found a mean difference of 0.04 kg in six trials outside Japan and called the loss unlikely to be clinically important. A meta-analysis found catechins with caffeine cut weight by 1.38 kg versus caffeine alone. But 300 mg of EGCG added nothing to a diet in obese women. One trial of 856.8 mg lowered weight from 76.8 kg to 75.7 kg.

What is the difference between EGCG and catechin?

EGCG is one specific tea catechin, the gallate ester of epigallocatechin, while “catechin” can name the whole group or a single compound. Green tea holds EGCG with EGC, ECG and EC. Many trials give a mixture of these, so a result for “green tea catechins” cannot be credited to EGCG alone. See our pages on catechin and epicatechin.

When is the best time to take EGCG?

With a meal, if you take an extract. No trial here tested time of day. Peak blood levels of free EGCG were more than 3.5 times higher on an empty stomach. USP’s label text for green tea extract says to take it with food, and that higher exposure is the reason for the label.

Does EGCG interact with medicines?

It can with at least one, the beta-blocker nadolol. A single dose of EGCG-rich extract lowered nadolol exposure to 0.72 and 0.60 of normal. Drinking green tea (700 ml a day for 14 days) cut its peak blood level by 85.3%. We found no controlled data for most other drugs, so ask your pharmacist about any regular medicine before starting an extract.