EGCG stands for ‘epigallocatechin-3-gallate’, a substance that falls into a chemical category called ‘catechins’, which themselves
categorized as ‘flavonoids’ (or ‘bioflavonoids’), and are also examples of ‘polyphenols’. EGCG is the most abundant catechin
found in tea.
Although tea is a traditional drink, only recently has it been studied extensively as a health-promoting beverage. Researchers
are examining it as a preventative for a number of diseases and ailments.
What we can’t tell you
In the U.S. and some other industrialized countries, government agencies like the U.S. Food and Drug Administration
have adopted censorship as a method for intensifying their control over the supplement industry and its customers.
Thus, FDA regulations prohibit us from telling you that any of our products are effective as medical treatments,
even if they are, in fact, effective.
Accordingly, we will limit our discussion of EGCG to a brief summary of relevant research,
and let you draw your own conclusions about what medical conditions it may be effective in treating.
Applications of EGCG
Medical researchers have recently become interested in EGCG for several major areas of application:
- cardiovascular diseases, high blood pressure, atherosclerosis
- neurodegenerative diseases
- blood clots, strokes, phlebitis
- obesity, excess body-fat
- diabetes and insulin resistance
- influenza, including bird (avian) flu
- other viral and bacterial infections, including dental infections
You might wonder why a single substance should have such broad applications in the body, while other familiar medical substances
(such as Prozac) have much more limited effects. The reason has to do with the mechanisms by which these substances work.
EGCG has a broad range of actions because it interferes with the chemical signals cells use to communicate with each other
— signals that are involved in all of the above ailments. Drugs like Prozac, on the other hand, interfere with processes that
affect mainly the activity of brain cells. Prescription drugs are carefully chosen for their specificity and government regulatory
agencies nix candidate drugs that have wide-ranging effects. Supplements, on the other hand, are often chosen for their wide-ranging
effects — why settle for just one benefit if you can have several for the price of one?
EGCG and similar catechins found in tea “…affect several biological pathways, including growth factor-mediated pathway, the
mitogen-activated protein (MAP) kinase-dependent pathway, and ubiquitin/proteasome degradation pathways.”. Catechins are “antioxidative, anti-hypertensive, anti-inflammatory, anti-proliferative, anti-thrombogenic, and lipid lowering”. They
- inhibit the key enzymes involved in lipid biosynthesis
- increase lipid metabolism
- reduce intestinal lipid absorption
- reduce visceral fat deposition
- regulate vascular tone by activating endothelial nitric oxide
- prevent vascular inflammation
- interfere with vascular cell growth factors involved in creating plaques in arteries
- remove iron atoms from plaques in the brain
- suppress platelet adhesion, thereby inhibiting thrombogenesis
- reduce lipid peroxidation and nitric-oxide-generated radicals leading to the oxidative stress
Cancer prevention is the most active area of green-tea research. A few intriguing studies with lab animals in the 1980s have led to hundreds of research papers being published every year on the subject. The cancer-preventive effects of green
tea are now widely supported by results from epidemiological, cell culture, animal and clinical studies. A broad range of cancer types are under investigation, including cancers of the lung, liver, mouth, colon, rectum, bladder,
stomach, pancreas, esophagus, prostate, breast, and skin.
Green tea polyphenols, and EGCG in particular, appear to act against cancer by preventing cancer cells from making use of
the chemical signaling molecules that would otherwise stimulate them to multiply and invade tissues. For example, the small
protein called ‘nuclear factor kappa B’ (NF-κB), which is used by many normal cells as a regulator of genes that control cell
proliferation and cell survival, is misregulated in cancer cells, allowing them to reproduce uncontrollably. EGCG has been shown to inhibit NF-κB activity
in various kinds of human cancer cells, thereby causing them to stop reproducing and self-destruct. This is just one example of a number of signaling pathways that
are misregulated in cancer cells and which EGCG interferes with. EGCG does not interfere with signaling in non-cancer cells.
Similarly, tumor invasiveness and metastasis depend on signaling molecules; EGCG interferes with some of these signaling pathways,
Polyphenols such as EGCG have been shown to reduce the growth of blood vessels in tumors — thereby starving tumors for energy. EGCG also has an antibacterial action that may prevent gastric cancer. Finally, EGCG stimulates the ‘differentiation’ of normal human skin cells, suggesting that it might reverse certain forms
of skin cancer.
The anti-cancer activities of EGCG and green tea have been confirmed not only in cell culture, but also in living animals
including humans, as indicated in these quotes from research papers:
- “Various animal studies have revealed that treatment with green tea inhibits tumor incidence and multiplicity in different
organ sites such as skin, lung, liver, stomach, mammary gland and colon.”
- “Green tea and its constituent molecules, including EGCG, have been found to prevent tumor formation in a wide range of tissues
in animal models.”
- “An inverse association between the risk of breast cancer and the intake of green tea has also been reported in Asian Americans.
Several epidemiological studies have shown that breast cancer progression is delayed in the Asian population that consumes
green tea on regular basis.”
Medical interest in the cardiovascular effects of green tea and EGCG centers on the prevention of atherosclerosis — the build-up
of fats and other materials in the walls of blood vessels. The past 20 years have seen hundreds of research papers on the
subject. Evidence for such cardiovascular benefits are based on:
- epidemiological studies showing that high green tea consumption is correlated with lower risk of cardiovascular disease
- measurement of blood lipids after consumption of tea catechins
- the use of markers for atherosclerosis and lipid radicals in conjunction with EGCG consumption
- measurement of normal damage to DNA and fatty acids, and its inhibition by EGCG.
As stated by Jochmann, Baumann, and Stangl in their review of the subject, “Green tea represents a promising tool for the
prevention of cardiovascular disorders.”
And S. Wolfram in his 2007 review concludes: “…intervention studies using similar amounts of green tea, containing 200-300
mg of EGCG, have demonstrated its usefulness for maintaining cardiovascular and metabolic health.”
The third major area of application for EGCG is the prevention or reversal of neurodegenerative diseases, including:
- Alzheimer’s Disease (‘AD’)
- Parkinson’s Disease (‘PD’)
- Amyotrophic Lateral Sclerosis (ALS, ‘Lou Gehrig’s Disease’)
- Huntington’s Disease
Why does EGCG have a beneficial effect for these diseases? One reason has to do with EGCG’s effects on iron atoms in the brain.
Iron has a known association with neurodegenerative diseases: it promotes the oxidative damage of nerve cells, and appears to play a role in maintaining plaques of ‘amyloid-beta’ protein
in the brains of Alzheimer’s patients. Laboratory experiments have shown that EGCG has strong iron-chelating activity — that is, EGCG readily removes iron atoms from in and around brain cells.
Researchers working on iron chelation as a treatment for neurodegenerative diseases are impressed by the results they have
obtained, as is indicated by these quotes from their published papers:
- “Thus, the natural non-toxic brain-permeable EGCG may provide a potential therapeutic approach for AD and other iron-associated
- “Also, EGCG reduced the levels of toxic amyloid-beta peptides…”
- “The diverse molecular mechanisms and cell signaling pathways participating in the neuroprotective/neurorescue and APP regulation/processing
actions of M-30 and EGCG, make these multifunctional compounds potential neuroprotective drugs for the treatment of neurodegenerative
diseases, such as PD, AD, Huntington's disease and amyotrophic lateral sclerosis.”
- “The treatment ((for ALS)) of more than 2.9 microg EGCG/g body weight significantly prolonged the symptom onset and life span,
preserved more survival signals, and attenuated death signals.”
High blood pressure is a condition which in itself has few symptoms. But the damage it causes to the body has significant
symptoms indeed. These include: heart attacks • strokes • kidney failure • eye damage • peripheral arterial disease • aneurysms. Methods for preventing high blood pressure are therefore valuable contributors to health.
EGCG consumption is of special interest to medical researchers interested in finding ways to protect the brain from stroke
- Researchers at Shujitsu University state that “in both black and green tea polyphenols attenuate blood pressure increases
through their antioxidant properties. Furthermore, because the amounts of polyphenols used in this experiment ((using rats))
correspond to those in ~1 L of tea, the regular consumption of black and green tea may also provide some protection against
hypertension in humans.”
- In stroke-prone mice, the regular ingestion of green tea catechins from an early age prevented the development of spontaneous
stroke. This effect was thought to be due to the prevention of high blood pressure.
- Even when strokes do occur, tea catechins reduce the damage they do to the brain.
Tea catechins like EGCG appear to offer a way to reduce body-fat with essentially no side-effects. A research group in Berlin
puts it this way:
- “Recent data from human studies indicate that the consumption of green tea and green tea extracts may help reduce body weight,
mainly body fat, by increasing postprandial thermogenesis and fat oxidation.” In other words, these substances increase the rate at which the body metabolizes fats after a meal, and cause the body temperature
Other researchers concur:
- “Reports have shown that green tea extract intake is associated with increased weight loss due to diet-induced thermogenesis,
which is generally attributed to the catechin epigallocatechin gallate.”
- “… EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of
Swiss researchers report that green tea, green tea catechins, and EGCG reduce all of these factors:
- the body’s production of new fat cells
- the rate of fat production
- the body’s total fat mass
- the body’s weight
- the absorption of fat from the digestive tract
- blood levels of lipids, free fatty acids, cholesterol, glucose, insulin, and leptin
Two types of body-fat are of special interest when it comes to body image and health: subcutaneous fat (fat in the skin),
and visceral fat (the fat that surrounds internal organs). Visceral fat, which is responsible for the paunchy belly syndrome,
is particularly hard to deal with — in many people this kind of fat responds poorly to dieting and exercise. Tea catechins
offer a different approach to reducing visceral fat, since they have been shown to “suppress deposition of visceral fat in
experimental animals and humans.”
The bioavailability of an orally-used supplement depends on several factors:
- how well it is absorbed from the digestive tract
- how fast it is metabolized
- how well it reaches the tissues and cells where it exerts its beneficial effects
When consumed with food, EGCG is absorbed poorly and is cleared quickly from the blood. It therefore has poor bioavailability under these conditions. This is why the amount of green tea that must be consumed in
order to achieve beneficial effects is often found to be quite high — many cups of tea per day.
EGCG’s effectiveness can, however, be enhanced in two ways:
- consume it on an empty stomach
- use the supplement form of EGCG instead of merely drinking green tea
- use it in combination with piperine
The supplement form of EGCG gives you far more EGCG than you can get by drinking any reasonable amount of green tea. And by
taking piperine supplements in addition to EGCG, you block enzymes that prevent EGCG absorption as well as those that metabolize
EGCG once it is in the body.
Are EGCG supplements useful for the conditions and purposes mentioned above?
We aren’t allowed to tell you, so you should take a look at some of the references cited here,
and then decide for yourself.