Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. In recent years it has become popular in Europe and North America and now green tea pills are touted for weight loss, as potent antioxidants, and for tumor prevention. What does the research say about their benefits? Do suchsupplements help with weight loss and are they an effective diet aid?
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Potential health benefit
Human research is still very early, but the potential health benefits ascribed to green tea include antioxidant effects, cancer chemoprevention, antiviral effects, blood thinning properties, improving cardiovascular health, slowing mental decline, enhancing weight loss, arthritis protection, and protecting the skin from the damage caused by ionizing radiation. The compound EGCG found in green tea has been shown to regulate dozens of disease-specific molecular targets. Long term human research is required before we determine the appropriate dosage and amount of green tea or green tea extract required to provide these health benefits.

Green Tea Extract, 100 mg, yielding 35 mg EGCG - Source Naturals
Green Tea Extract offers a convenient way to get the benefits of green tea in a highly concentrated green tea pill form.  This green tea extract is standardized for bioflavonoid-like antioxidants known as polyphenols, particularly Epigallocatechin Gallate which has been found in scientific studies to be a potent antioxidant. Green tea antioxidants are likely to become more popular with time.

Supplement Facts
Calcium
Green Tea Extract Yielding 35 mg epigallocatechin gallate

Suggested Use: 1 green tea extract tablet a few times a week with breakfast or lunch. Take green tea extract pill in the morning or midday before or with a meal. Evening use may lead to mild insomnia.
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Tea information and consumption
Tea is the most widely consumed beverage aside from water. Green tea contains polyphenolic compounds, which account for 30% of the dry weight of the leaves. Most of the polyphenols are flavanols, of which (-)-epigallocatechin-3-gallate is the most abundant. Tea is manufactured in three basic forms:

Black Tea -- During black tea production, oxidation is promoted so that most of these substances are oxidized.
Green tea -- Green tea is prepared in such a way as to prevent the oxidation of green leaf polyphenols.
Oolong tea --  Oolong tea is a partially oxidized product. Of the approximately 3 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea.

What's in green tea?
Fresh green tea leaf is unusually rich in polyphenols which may constitute up to 30% of the dry leaf weight. Polyphenols include catechins, flavanols, chlorogenic acid, epigallocatechin gallate (EGCG), and one unique to tea, theogallin. Caffeine in green tea is present at an average level of 3% along with very small amounts of methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea.

Green Tea and Weight Loss Diet, a fat burner?
Human studies regarding the benefit of green tea in weight loss have not shown consistent results. In one study mentioned below, daily consumption of green tea for 12 weeks reduced body fat. Green tea could enhance metabolism. Scientists are still evaluating whether a green tea pill by itself leads to weight loss. See below for more green tea and weight loss research information. If you plan to drink green tea for weight loss, avoid drinking after mid afternoon or early evening so that your sleep is not disturbed.

Anti-obesity effects of green tea: from bedside to bench.
Mol Nutr Food Res. 2006.
Green tea, green tea catechins, and epigallocatechin gallate have been demonstrated in cell culture and animal models of obesity to reduce adipocyte differentiation and proliferation, lipogenesis, fat mass, body weight, fat absorption, plasma levels of triglycerides, free fatty acids, cholesterol, glucose, insulin and leptin, as well as to increase beta-oxidation and thermogenesis. Adipose tissue, liver, intestine, and skeletal muscle are target organs of green tea, mediating its anti-obesity effects. Studies conducted with human subjects report reduced body weight and body fat, as well as increased fat oxidation and thermogenesis and thereby confirm findings in cell culture systems and animal models of obesity. There is still a need for well-designed and controlled clinical studies to validate the existing and encouraging human studies.

Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men.
American Journal of Clinical Nutrition, 2005
Catechins, the major component of green tea extract, have various physiologic effects. There are few studies, however, on the effects of catechins on body fat reduction in humans. We investigated the effect of catechins from green tea on body fat reduction and the relation between oxidized LDL and body fat variables. Design: After a 2-wk diet run-in period, healthy Japanese men were divided into 2 groups with similar BMI and waist circumference distributions. A 12-wk double-blind study was performed in which the subjects ingested 1 bottle oolong tea /d containing 690 mg catechins (green tea extract group; n = 17) or 1 bottle oolong tea /d containing 22 mg catechins. Body weight, BMI, waist circumference, body fat mass, and subcutaneous fat area were significantly lower in the green tea extract group than in the control group. Conclusion: Daily consumption of green tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins from green tea might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity.

Effect of long-term oral administration of green tea extract on weight gain and glucose tolerance in Zucker diabetic (ZDF) rats.
J Herb Pharmacother. 2005.
There have been some claims that green tea reduces weight and lowers blood glucose in diabetes. Intraperitoneal injections of green tea catechins in diabetic rats have shown beneficial effects. To determine if oral administration of green tea would prevent development of diabetes, young Zucker diabetic rats were dosed with green tea extract containing 50-125 mg/kg of Epigallocatechin gallate (EGCG) starting at 7 weeks of age, before the appearance of excessive weight gain and glucose elevation. While there was a trend toward lower weight gain and average daily glucose, there was no statistically significant difference.

Additional health benefits
Green tea has several potential health benefits that are slowly being discovered, here are some preliminary results:
 
Alzheimer's
An ingredient in green tea that researchers think might fight cancer may also protect the brain from the memory-destroying Alzheimer’s disease. Scientists injected mice with an antioxidant from green tea called epigallocatechin-3-gallate and said it decreased production of beta-amyloid, a protein that forms the plaques that clog the brains of Alzheimer’s victims. Several months of injections reduced plaque formation by as much as 50 percent.
   Previous research had mentioned EGCG has protective effects against betaA-induced neuronal apoptosis (cell death) through scavenging reactive oxygen species, which may be beneficial for the prevention of Alzheimer's disease.
   A higher consumption of green tea is associated with a lower prevalence of cognitive impairment.

Arthritis
Some green tea catechins are chondroprotective (protecting cartilage) in lab studies, and that consumption of green tea may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy when ingested as tea or capsule.

Blood thinner
Anti-platelet (blood thinning) activity of green tea catechins is mediated by inhibition of cytoplasmic calcium increase.

Cancer:
There is growing evidence that drinking green tea may reduce the risk for various types of cancer. However, little is known regarding the cancer preventive benefit of green tea supplements and the appropriate dosage.

Researchers at the University of Murcia in Spain and the John Innes Cente in Norwich, England have shown that a compound called EGCG in green tea prevents cancer cells from growing by binding to a specific enzyme. They showed for the first time that EGCG, which is present in green tea at relatively high concentrations, inhibits the enzyme dihydrofolate reductase, which is a recognized, established target for anti-cancer drugs. Green tea has about five times as much EGCG as regular tea. Green tea has been suspected to decrease rates of certain cancers but scientists were not sure what compounds were involved or how they worked. Nor had they determined how much green tea a person would have to drink to have a beneficial effect. EGCG is probably just one of a number of anti-cancer mechanisms in green tea.

Epidemiological data have suggested that EGCG may provide protective effects against hormone related cancers, namely breast or prostate cancer.
   Researchers at the University of Murcia in Spain and the John Innes Center in Norwich, England have shown that EGCG prevents cancer cells from growing by binding to a specific enzyme. They showed for the first time that it inhibits the enzyme dihydrofolate reductase, which is a recognized, established target for anti-cancer drugs. Green tea has about five times as much EGCG as regular tea. Green tea has been suspected to decrease rates of certain cancers but scientists were not sure what compounds were involved or how they worked. Nor had they determined how much green tea a person would have to drink to have a beneficial effect. EGCG is probably just one of a number of anti-cancer mechanisms in green tea. EGCG targets multiple MMP-mediated cellular events in cancer cells and provides a new mechanism for the anticancer properties of that molecule. Understanding the basic principles by which EGCG inhibits tumour invasion and angiogenesis may lead to the development of new therapeutic strategies, in addition to supporting the role of green tea as a cancer chemopreventive agent.
     EGCG targets multiple MMP-mediated cellular events in cancer cells and provides a new mechanism for the anticancer properties of that molecule.

Bladder cancer
Herbal Green tea extract may interfere with a process that helps early bladder cancer to spread throughout the body. The findings bolster ongoing studies into green tea extract as a cancer treatment -- and may give green tea drinkers more reason to savor every cup. The investigators found that when they exposed human bladder cells to both a cancer-causing chemical and green tea extract, the extract interfered with a particular process by which early cancer cells become invasive and spread throughout body tissue.

Reduced breast cancer risk
Compounds in green tea may help protect women against breast cancer. Rats who drank water containing green tea had reductions in the size and malignancy of breast tumors compared with rats that drank only water. Additionally, the tumors of tea-drinking rats developed later and were less invasive.
   While more research needs to be conducted, the findings, coupled with observations of lower rates of breast cancer in countries where green tea is consumed daily, suggest that green tea may benefit women as part of an overall healthy diet.
   According to the report in the July issue of the Journal of Cellular Biochemistry, polyphenols, compounds that are abundant in green tea, red wine and olive oil, may protect against various types of cancer. Polyphenols are potent antioxidants, compounds that help neutralize disease-causing free radicals. These cell-damaging molecules occur naturally in the body and are linked with heart disease, aging and a number of other disorders.
   Dry green tea leaves, which are about 40% polyphenols by weight, may also reduce the risk of cancer of the stomach, lung, colon, rectum, liver and pancreas, study findings have suggested.

Leukemia
Green tea may help treat a form of adulthood leukemia. Doctors at the Mayo Clinic in Rochester, Minnesota, found that of four patients who started drinking green tea or taking green tea extracts, three showed clear improvements in their condition in the following months. The patients all had chronic lymphocytic leukemia, or CLL, a form of leukemia that usually arises during or after middle-age and typically progresses slowly. Like all types of leukemia, CLL is a cancer of the blood and bone marrow, in which abnormal white blood cells replace healthy blood cells. A study showed that one compound found in green tea, known as EGCG, was able to kill cancer cells that were taken from CLL patients and put in a test tube with the tea compound. Leukemia Research, online December 1, 2005.

Depression
Dr. Kaijun Niu, at Tohoku University Graduate School of Biomedical Engineering in Sendai, found men and women aged 70 and older who drank four or more, versus one or fewer, cups of green tea daily were less likely to have symptoms of depression. Dr. Kaijun Niu published the results of this study in the American Journal of Clinical Nutrition, 2009.

Diabetes
Epigallocatechin gallate supplementation alleviates diabetes in rodents.
 J Nutr. 2006.
This study investigated the antidiabetic effects of the most abundant green tea catechin, epigallocatechin gallate (EGCG, TEAVIGO), in rodent models of type 2 diabetes mellitus and H4IIE rat hepatoma cells. We assessed glucose and insulin tolerance in db/db mice and ZDF rats after they ingested EGCG. This study shows that EGCG beneficially modifies glucose and lipid metabolism in H4IIE cells and markedly enhances glucose tolerance in diabetic rodents. Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes mellitus.

Gums
Japanese men who drink green tea on a regular basis have healthier gums. Journal of Periodontology, 2009.

High blood pressure
Drinkers of green tea and oolong tea are less likely to develop hypertension than nondrinkers.

HIV
Epigallocatechin-3-gallate has been suggested to have antiviral activity. To determine the effects of EGCG on HIV infection, peripheral blood lymphocytes infected with HIV were incubated with increasing concentrations and it strongly inhibited the replication of the HIV virus.

Mental Decline
People who regularly drink green tea may have a lesser risk of mental decline as they grow older. A study of more than 1,000 Japanese adults in their 70s and beyond, found that the more green tea men and women drank, the lower their odds of having cognitive impairment. Older adults who drank two or more cups of green tea per day were about half as likely to show cognitive impairment as those who drank three cups or less each week. Men and women who averaged one cup per day fell somewhere in between.

Daily consumption of green tea catechin delays memory regression in aged mice.
Biogerontology. 2006.
Because oxidative stress has been implicated in brain senescence, we investigated the effects of green tea catechin (GT-catechin), a potential antioxidant, in senescence-accelerated (SAMP10) mice. The mouse is a model of brain senescence with short life span, cerebral atrophy and cognitive dysfunction. Mice were fed water containing 0.02% GT-catechin from 1- to 15-month-old. The mean dose was about 35 mg/kg/day. We found that daily consumption of GT-catechin prevented memory regression and DNA oxidative damage in these mice. GT-catechin did not prolong the lifetime of SAMP10 mice, but it did delay brain senescence.

Does Green Tea Enhance Longevity?
According to a Japanese study, those who consumed the most green tea over an 11-year period were less likely to die from cardiovascular disease or any other cause, except cancer, than were the less-frequent green tea drinkers. However, because this was an observational study, the debate on the effects of green tea on heart disease and cancer is not over. Although laboratory and animal studies have shown that the polyphenols in green tea may be protective against cardiovascular disease and cancer, it is not clear if these findings extend to humans. Dr. Kuriyama and colleagues analyzed information on 40,530 Japanese adults, 40 to 79 years old, who participated in the Ohsaki National Health Insurance Cohort Study. The subjects, who were followed from 1995 to 2005, were from a northeastern region of the country where most of the adults drink green tea three or more times per day. Adults who drank the most green tea were the least likely to die from cardiovascular disease. Men who consumed at least five cups of green tea each day were 12 percent less likely to die from any cause. Whereas, women who drank five or more cups of green tea each day were 23 percent less likely to die from any cause and 31 percent less likely to die from cardiovascular disease.
     Dr. Sahelian says: For the time being I prefer people drink a variety of herbal teas as opposed to predominantly one type of tea.

Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study.
JAMA. 2006.
Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear. We investigated the associations between green tea consumption and all-cause and cause-specific mortality with the Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40,530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality. Results: Over 11 years of follow-up (follow-up rate, 86%, 4209 participants died, and over 7 years of follow-up (follow-up rate, 89%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Conclusion: Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.

Green Tea Side effects, safety, risk
Green tea has caffeine and methylxanthines, so avoid drinking or taking the capsules in the evening. I have not come across any other common green tea side effects at this time except this one caution:

Caution: In rare cases extracts from green tea have been reported to adversely affect the liver. Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice. If you plan to take green tea extract for prolonged periods, take a week off each month.

Q. I have a question about the recent decision to put warning labels on supplements containing green tea extracts. it warns of possible liver damage. Are there supplements derived from green tea extracts which will not be easily identifiable by their labels? For example if a supplement was advertised to contain "antioxidants" how would the consumer know if it contained the dangerous chemical compound in the green tea study?
   A. The study that found green tea extract polyphenols may damage liver tissue used high doses injected into small mammals. Many Japanese drink green tea several cups a day without problems. I am not concerned that taking a green tea supplement at one capsule or tablet a few times a week would cause any liver problems. As with any supplement, it is a good idea to take breaks from use. Low dosages of many supplements are often of benefit, but high dosages could be harmful.

Q. Although I am aware and have read on many websites that Green Tea has anti cancer properties, i was alarmed to read today on a couple of websites that it can actually cause Esophageal Cancer! This is what i read from the site as one of the possible side effects: "Some people show hypersensitivity reactions with green tea. Others develop the condition after long-term use characterized by hives, swelling of ears, lips, tongue and face, difficulty breathing, closing of the throat and skin irritation. Another grave side effect that can be caused by heavy and long-term consumption of green tea is esophageal cancer. There are agents that remain and accumulate in the esophageal area leading to the development of cysts and tumors. Too much green tea can cause a variety of side effects such as anxiety, insomnia, nervousness, irritability, mood swings, interrupted sleep, cardiac arrhythmia, headache, heartburn, loss of appetite, gastrointestinal upset, diarrhea and constipation. It can also interact with other substances thereby causing problems. Do not drink tea if you're taking blood thinners like warfarin or Coumadin or it might cause hemorrhage or internal bleeding.
Herbal teas in general have been suggested to be contributory to the development of cancer. There seem to be carcinogenic effects that come with chronic use. Teas high in tannin may lead to iron deficiency and microcytic anemia. Other associated effects are liver and kidney failure and bronchial and respiratory problems."
This concerns me as i have been taking green tea for a few years now and just recently have been taking about 4 capsules a day, each one at 300mg (polyphenols 95% & EGCG 40%) Is this to much to be taken daily? I also take Acai Berry as well.
    A. Too much of a good thing is not so good. Esophageal cancer is quite rare and is not a major concern. Most long term epidemiological studies have shown benefits from drinking green tea and Asians who drink a lot of this tea do not show any noticeable harm. However, it is a good idea to be reasonable in one's consumption of this product either in tea form or in pills, and it is also a good idea to take occasional breaks.

Availability
There are countless green tea products, including bags, capsules, tablets, powder, green tea gum, combinations with other supplements and organic. Green tea is sold by raw material suppliers in different extracts, ranging from 30%-95%, standardized to green tea catechins.

Research
Compounds found in green tea may prevent the development of prostate cancer in men with a pre-cancerous condition called high-grade intraepithelial neoplasia (PIN). About 30,000 men die from prostate cancer in the United States every year. High-grade PIN progresses to invasive prostate cancer within a year in about 30 percent of men and no treatment is given to these men with high-grade PIN until prostate cancer is diagnosed. Green tea catechins may be one answer. A trial was performedinvolving men with high-grade PIN, who were given an inactive placebo preparation or one containing 600 milligrams of green tea catechins daily, "equivalent to 12-15 cups of green tea infusion, that is about two times the average intake in Asian countries. After a year, only 1 man among 32 in the green tea catechins group developed prostate cancer, a rate of only 3 percent. In contrast, 9 out of 30 men treated with placebo developed prostate cancer, for the expected rate of 30 percent.

Raw Material Supply
Green tea raw material suppliers literally have dozens of forms and extracts, for example the following:
Green tea caffeine 30% to 80%
catechins 20% ~ 90%;
EGCG 10% ~ 98%;
ECG, EGCg 20- 99% (HPLC)
ECG 90%, 95%;
L-theanine 20% ~ 35% ;
L-theanine 20- 50% (HPLC)
polyphenols 20%-90% (UV-VIS)
saponins 50% ~ 70%.

Emails
Q. Will drinking a lot of green tea cause free estrogen to go up in the body (due to the phytoestrogens)?  If so, could this potentially make someone estrogen dominant?
   A. Not likely. Phytoestrogens have both estrogen agonist and estrogen antagonist activity in different tissues. They don't work the same way as regular estrogen hormone.

Q. Can this supplement be used together with another anti cancer agent called DIM?
   A. Probably as long as the dosages are reasonable, see diindolemethane dim for additional research studies.

Q. Recently I discovered your web page regarding health benefits of green tea. Thank you the info was very useful. If you have a moment perhaps you could clarify something for me though. A friend of mine yesterday said she read that if you drink green tea with cow's milk that it will completely destroy the antioxidant properties of green tea. Do you know if this is true?
   A. We have no indications at this time that drinking green tea with milk destroys its benefits.

Q. Is green tea okay to drink during pregnancy? Is it good for nausea during pregnancy.
   A. I can't foresee green tea, a cup a day, to pose any problems during pregnancy. I don't think it helps relieve nausea.

Q. I am trying my best to lose weight, but am unfortunately not noticing any difference. I eat healthy food and do exercise, so I am considering taking a green tea tablet to try and burn fat. I read off a bottle of green tea tablets that you should consult with your physician if you are on medications before starting the tablets. I have minor epilepsy and take three medications to keep it under control. I take Keppra, Tegretol XR and Lamictal everyday morning and night. Can I take green tea tablets as well, without any side effects from my epilepsy drugs?
   A. Green tea tablets are unlikely to cause weight loss by themselves. Anyone with a seizure disorder needs to be careful taking herbs, especially those that have a stimulating nature.

Q. Do you have a green tea recipe? What brand green tea should I use?
   A. I personally don't. But I am sure you can find a green tea recipe by doing an internet search. Various brands of green tea are available including Lipton green tea, Arizona green tea. I have recently come across some restaurants that serve green chai tea and even heard of green tea frappuccino recipe. I think alternating different green tea products is a good option.

Q. Do any doctors advocate that people take green tea supplements for their antioxidant and other benefits? If so, what's the amount of green tea they -- or that you -- advise taking daily? I find studies showing green tea benefits this or that, but I can't find anyone who actually suggests a daily amount.
   A. There is no single answer since there are many factors that are involved in green tea dosage including age, medical condition, other supplements taken, other medicines used, activity level, whether they drink coffee or tea and how much, sleep patterns, etc. Also it depends on the extract potency, the quality of the green tea, etc.

Q. If I drink a lot of green tea will it flush out the good stuff in my body and mess up my electrolytes? I was told that if I drink green tea all day or a lot of it then it isn't good for me.
   A. As a general rule, it is not a good idea to drink or eat too much of the same fluid or food. Too much green tea could cause alertness and interfere with sleep since green tea has caffeine and other methyl-xanthines such as theobromine which cause shallow sleep if ingested in the evening. It is a good idea to drink a variety of different herbal teas, not just exclusively green tea.

Q. I have bought most of your excellent soft cover booklets over the years, and always read carefully your materials when they come up in my research engine etc. I'm a daily user of fresh juice extractor drinks plus nutraceuticals (capsule powers) I add to them, for health, fitness, metabolism controls and nootropic purposes going toward the alkaline level etc. I've read your data on green tea...and while I've begun doing it recently...my question is. Is it okay to add the contents of a quality green tea bag to my drinks as a powder for supplementary purposes. How far removed is an extract from the green tea bag powder - As you know a really good supplemented nutritional program can be quite expensive. So if this green tea bag content has no bad side effects, I would like to continue this practice.
   A. I don't see any reason why the green tea bag contents cannot be used. Over time, use different green tea bags from different sources.