Green tea is derived from the unoxidised and unfermented leaves of Camellia sinensis and contains the polyphenol Epigallocatechin-gallate, or EGCG, a powerful antioxidant, anti-inflammatory and free-radical scavenger, which inhibits carcinogenesis by affecting a wide variety of pathways, causes apoptosis and cell cycle arrest selectively in both cancer cells and cancer stem cells and inhibits epigenetic modifications in animal models.
Green tea protects and corrects cancer
Green tea has been extensively research and has numerous studies suggesting it can prevent cancer. Increasingly there is a growing volume of research showing it can help fight cancer too - in the laboratory, in animal studies and in Human Observational studies. Perhaps the most important review of EGCG is that of Dr. Cord Naujokat of the Centre of Immunology in Heidelberg Hospital and the Centre of Targeted Oncology in Neckersteinach, Germany; and Dr Dwight McKee of Integrative Cancer Consulting in California USA where they list chapter and verse on the abilities of EGCG to deal with Cancer Stem Cells, the cells at the heart of cancers, which are not killed by current drugs and can regenerate the tumour (6).
Studies show it can reduce the spread of cancer; and it also has benefits with leukemia, colorectal cancer, prostate cancer, breast cancer (Er+ve, and TNBC) and head and neck cancer. It specifically inhibits the self-renewal pathways of Cancer Stem Cells (CSCs). Clinical Studies with humans are currently taking place with breast cancer, prostate cancer and bladder cancer.
EGCG is only about 70 per cent of the total catchetin content of Green Tea though. EGCG is sometimes referred to as epigallocatechin-3-gallate.
EGCG works synergistically in many situations with turmeric, or curcumin, another known CSC attacker.
Cancer Watch has covered many research studies, for example:
1. The Tohoku School of Medicine produced a 9-year study following 42,000 people. The study looked at blood cancers and cancer in the lymph nodes and showed that consuming 5 cups of green tea per day resulted in a 40 per cent reduction in the former, and a 50 per cent reduction in the latter. (American Journal of Epidemiology 2009)
2. The Mayo Clinic have taken earlier studies and findings into Clinical Trials with Green Tea and chronic lymphocytic leukaemia, (CLL). (Journal of Clinical Oncology). Using Polyphenon E (derived from EGCG) at a dosage of 400-2000 mg per day for 2 months, Phase I Clinical Trials showed that high doses helped decrease the damaged white cell counts by one third in CLL patients, causing cancer regression. Those people with enlarged lymph nodes showed a 50 per cent reduction.
3. In 2 randomized clinical trials on men with a high risk of prostate cancer, those taking EGCG developed significantly less disease than those on the placebo (National Cancer Institute)
4. Other studies have shown that EGCG actually accumulates in the prostate gland and makes the cancer cells grow more slowly. It also reduces PSA levels and IGF-1 levels (1).
5. There is also a 2010 review with a number of cancers showing that EGCG reduces metastases (2)
6. In breast cancer, EGCG has been shown able to prevent breast cancer, and to prevent breast cancer recurrence by suppressing growth of the cancer (3).
7. In 2012, epigeneticist Dr. Young S. Kim, working for the National Cancer Institute, concluded that EGCG was one of a number of polyphenol compounds that could prevent a stem cell cancer re-growing (others - curcumin, piperine, resveratrol, genistein), and she stated that if you could not consume the food, you should use a quality supplement.
8. The "Big Five' CSC phytochemicals of Naujokat and McKee that can block CSCs were EGCG, Curcumin, Resveratrol, Sulforaphanes and Genistein.
9. Professor Robert Thomas of Addenbrooks used EGCG in his POMI-T formula for men with prostate cancer along sife curcumin, pomegranate and broccoli. POMI-T has full Clinical Trials behind it with prostate cancer where it reduces PSA scores by over 60%.
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An overview on Green tea
Much of the early research on Green tea used Epidemiology studies. It is true that the people of South East Asia, Japan and China drink green tea and develop less cancers. But their environments at home are less toxic, their meat consumption less, garlic, vegetable and fruit consumption higher, stress less etc. And when they come to live in the West, even the green tea drinkers can develop cancer.
However, research has moved on, with active ingredients identified and isolated, and Laboratory and Animal studies showing clear benefits, not just for prevention, but in terms of helping correct chronic illness.
The origin of Green Tea
It will surprise most people to know that both green tea and the black stuff we've been drinking in the UK for several hundred years, come from the same plant, Camelia sinensis, found in tropical and sub-tropical regions like India and China.
Black tea, when dried, is fermented and oxidised. Green tea is left unfermented, and then merely steamed. Many experts now believe that green tea is thus a better, more whole, source of natural chemicals like proteins, sugars and vitamins and, in particular, natural antioxidants.
The history of Green tea
Legend has it that green tea was "discovered" by Emperor Shea Nung in 2737 BC in China, by accident when some wild tea leaves ended up in the water he was boiling.
Around AD 800 Buddhist monks took the drink to Japan, where the tea drinking ceremony (the cha-no-yo) evolved. By the 16th century tea was heading West as explorers visited Asia.
General Health benefits of Green tea
The active ingredients vary considerably depending upon where the tea was grown. Young leaves and buds are the usual parts used.
Young leaves and buds are the usual parts used
Green tea contains caffeine and thus has a mild stimulating effect. But the greatest benefits are due to a group of flavenoids called polyphenols, which the lack of processing in green tea leaves unaltered whilst the drying process concentrates.
Cardiovascular benefits - Polyphenols are potent antioxidants and have been shown to protect against heart disease, as they can prevent the formation of LDL, or so-called "bad" cholesterol.
By preventing this oxidation, the polyphenols prevent plaque building and fatty deposits forming on the walls of the arteries, as well as lowering cholesterol and triglyceride levels overall (Cedars-Sinai Medical Centre), whilst increasing "good" HDL cholesterol (Saitama Cancer Centre Research Institute, Japan). These effects are particularly noticeable when consumption exceeds 10 cups per day.
In a study reported in the European Journal of Preventive Cardiology, 100,000 people were followed over time and divided into two groups - those drinking more than 3 cups a week; those drinking 3 or less. After seven years those who drank the higher levels were 20 per cent less likely to suffer from heart disease or stroke and 22 per cent less likely to die from either, and 15 per cent less likely to die from other health issues. Five years later the results were even stronger, climbing to 39 per cent, 56 per cent and 29 per cent respectively. The researchers felt that the results came from the strong anti-inflammatory benefits of the Green tea.
Japanese research with 82,000 adults between the ages of 45 and 74 showed that drinking green tea could significantly reduce the risk of stroke (5).
Brain benefits - Researchers from the University of Pennsylvania and Boston Biomedical Research Institute have shown that EGCG helps protect the brain from the build up of amyloid proteins (Nat Chem Biol Dec 2009). They concluded from their studies that Green Tea would help prevent Parkinson's and Alzheimer’s, and could also be used in treatment.
Colds and flu - Other 2009 research on Green Tea (Journal of American Coillege of Nutrition, 2009) showed that it could prevent colds and flu. The study compared people taking a green tea supplement with those taking a placebo and showed one third ;less colds and flu in the green tea supplement group.
Arthritis - Research has shown that, because EGCG is anti-inflammatory, it has benefits with arthritis, and rheumatoid arthritis (4).
Glucose control, diabetes - Catechins are known to be up to five times more potent as antioxidants than Vitamin E. They are important in maintaining metabolic pathways and can stop the uptake of glucose by fat cells. Green tea and catechins can also reduce appetite according to research in the International Journal of Obesity. A balancing effect on blood sugar levels may also be of significance in diabetes, and the limiting effect on glucose uptake, the reduction in appetite and the stimulation of energy production in cells due to caffeine levels all can result in weight loss (University of Geneva, November 1999 - American Journal of Clinical Nutrition). In the latter study, researchers found that men who were given a combination of caffeine and green tea extract burned more calories than those given only caffeine or a placebo.
A Japanese study (7) in 2013 showed that Gree tea could be a strong preventative agent and therapeutic for Type-2 diabetes and obesity.
In a comprehensive review (8) of published research, Green tea consumption is associated with lower levels of fasting blood sugar and A1c levels as well as lowered insulin levels.
Green tea is also claimed to improve skin tone, smooth out wrinkles and even to help you slim.
More on Green tea and cancer
The polyphenol, epigallocatechin gallate (EGCG), seems the most active and the most potent. Early studies used it topically in the prevention of UV-induced skin cancer, while other studies (Nature 1997, Jankun) have shown that it can inhibit the spread of cancer.
Overall the more green tea drank, the better the results
Research from Perth University in 2002 showed drinking just one cup per day reduced ovarian cancer risk by 60 per cent, and in 2003 the same group showed it reduced prostate cancer risk by 33 per cent.
By 2009, they had turned their attentions to breast cancer and showed that Green Tea could reduce breast cancer rates by 40 per cent. And if women ate mushrooms daily as well as drinking green tea, only 1 in ten of them would get breast cancer compared to those who consumed neither! Green teas active ingredients are also thought to be anti-oestrogenic.
Research from the Shanghai Cancer Institute looked at oesophageal cancer among those who neither drank alcohol nor smoked (two of the main causes). They found drinking green tea further and significantly reduced risk, starting at 57 per cent in the no alcohol group and 60 per cent amongst the non-smokers. Overall the more green tea drank, the better the results. (Journal of the NCI).
EGCG has been found to block an enzyme, ornithine decarboxylase, which tells cells to multiply at cancer cell rates. By blocking this enzyme, cell death occurs.
EGCG is also known to cause good bacteria in the intestine to flourish, thus aiding your first line of defence.
But perhaps the research of most significance was reported in icon in July/August 2004. The prestigious Mayo Clinic in the USA researched green tea with leukaemia patients and concluded that "4-7 cups per day stops leukaemia in its tracks". I’m not sure whether it does or not but I think if I had leukaemia, I’d try it!
Other studies have suggested that green tea has a positive effect in breast cancer, liver cancer and colon cancer prevention, and there is also work showing it improves the positive effects and reduces the negative effects with people undergoing radiotherapy and chemotherapy.
Intake should probably be around two to three cups per day, although some experts recommend ten.
Other facts on Green tea
It does contain relatively high levels of caffeine and you may prefer to drink decaffeinated versions.
The bitter taste can be offset in other blends, for example green tea with jasmine or with the powerful antioxidant lemongrass, or by sweetening with honey. The Japanese in particular have a whole range of soft drinks based on green tea but these do have quite high sugar content.
One downside of green tea is that it can cause discolouration of the teeth, turning them yellow or even green.
One cup of green tea can contain as much as 130 mg of polyphenols. But how you store it, how you brew it, the source and age of the tea are all factors in this.
Green tea is also available in supplement form and the recommended dose is about 300 mg once per day.
Finally, white tea is now growing fast in the popularity stakes, being made totally from the unopened tea buds. It has even more polyphenols than green. White tea gets its name from the white hairs on the buds but it makes a golden coloured tea. Laboratory studies suggest a positive effect with colon polyps (UCLA).
Are there any side-effects to Green tea?
Green tea has been drunk for 5000 years without ill effects. But there are side effects, the most obvious being from the caffeine content, like tremors and sleeplessness at high levels of consumption. Other side effects like diarrhoea and stomach irritation have been reported.
Green tea benefits summary
The main objection to green tea is its taste. Once you overcome that dry, blotting paper effect, the real question is, "why not?".Alternatively, and this is a personal observation, Matcha Green tea (which uses the tips of young leaves) overcomes many of the taste issues. I particularly like the one with a splash of peppermint.
It clearly does have significant health benefits across the spectrum of chronic illnesses - cancer, type-2 diabetes, obesity, cardiovascular disease, stroke risk, arthritis, Alzheimer's, brain health - it's an anti-inflammatory and has a good antioxidant content; it should be a part of your natural antioxidant repertoire. If you have a cancer, it would seem a sensible step to move on to Green tea from your coffee or normal cuppa. Especially as we covered German research in Cancer Watch in 2008/9 which showed that the antioxidant benefits in normal tea were completely negated by adding cows' milk!
What are you waiting for? Drink 5 cups a day - or, if you have to, supplement!
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Finally, research from Perth University shows that drinking green tea AND eating medicinal mushrooms can cut the risk of breast cancer by a whopping 90 per cent.
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Ref
1. https://www.cancer.gov/about-cancer/treatment/cam/patient/prostate-supplements-pdq#section/_175
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3142888/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4127621/
4. http://onlinelibrary.wiley.com/doi/10.1002/art.39447/abstract
5. https://www.webmd.com/stroke/news/20130314/green-tea-cuts-stroke-risk
6. The "Big Five" Phytochemicals targeting Cancer stem Cells - 2020, Researchgate
7. The effects of Green tea with Obesity and Type-2 diabetes
8. Comprehensive review; green tea and gliucose and insulin levels
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Please be clear: At CANCERactive we do not consider the above compound to be a cure for cancer, despite what the research says or experts doing the research may claim. The above, is an article on the compound from published research and expert opinion in the public domain. At CANCERactive we do not believe that any single compound (drug, vitamin, whatever) is a cure for cancer. We believe that people can significantly increase their personal odds of survival by building an Integrated Programme of treatments. Equally, cancer prevention is best practiced through a width of measures.