Green tea beneficial both in the prevention and remission of cancer

The results of research at the Medical College of Georgia in Augusta indicated compounds in green tea selectively induced cell death only in oral cancer cells while ignoring normal cells.

The authors of the study conclude that green tea could inhibit, delay or even reverse cancer.

"Green tea appears to be chemopreventative, both before the onset of malignancy and following cancer treatment", states the study titled "Chemoprevention of Oral Cancer by Green Tea".

The study was published in the March/April 2001 issue of the journal "General Dentistry", which is published by the Academy of General Dentistry .

Although the research must be duplicated before green tea is labelled as a public health strategy and a bona-fide anti-cancer agent, lead study author/cell biologist Stephen Hsu said:

"The evidence of benefits appears to be sound, but we need a lot of different groups to agree on this and there is research going on in various places that will help answer that," he said, referring to a human trial at the University of Texas M.D. Anderson Cancer Centre involving oral cancer and green tea.

Hsu, whose research was funded by his academic institution, not the tea industry, said while further trials are being conducted, there is no reason why people shouldn't indulge in green tea.

"There are a lot of different brands, but that doesn't appear to make a difference. What does matter is that people choose a high quality tea that is without additives and has not been processed, because the fermentation process reduces the concentration of polyphenols and their beneficial effects."

Green Tea and Oral Cancer

The role of your cancer health professional is to create an environment of openness and trust, and to help in making informed decisions about alternative/complementary therapies. Collaboration will improve the safe integration of all therapies during your experience with cancer. The "Summary" and "Professional Evaluation / Critique" sections of this Unconventional manual are cited directly from the medical literature, and are intended to help in the objective evaluation of alternative/complementary therapies.

Summary

"Moderate consumption of green tea appears safe. There is some evidence that green tea may prevent the occurrence of some forms of cancer, but the mechanisms of action of its specific constituents are poorly understood. Preliminary evidence exists of the potential effectiveness of green tea as a treatment for cancer. Further research into the effects of green tea and some of its constituents would be worthwhile." (Kaegi)

Description / Source / Components

"Each year about 2.5 million tons of tea are manufactured from the dried leaves and leaf buds of the shrub Camellia sinensis. ... Green tea, which is not fermented, is made by steaming or pan-frying tea leaves and then drying them. It accounts for about 20% of world production and is mostly consumed in China and Japan , where it has been used medicinally as a stimulant and digestive remedy for about 5000 years." (Kaegi)

"Green tea is different from black tea in that it [green tea] is produced from leaves that have been withered, rolled, fermented, and dried. Because of the curing process, the properties of the green tea are very similar to that of the fresh leaf." (Fetrow)

"Black teas - the preferred drink in Europe and the Americas - are partially dried, crushed, allowed to "ferment" or oxidize in heat for a few hours, then fully dried. ... Green teas, the preferred drink in Asia , are not crushed and oxidized. Instead they are steamed, then rolled and dried. The steaming actually prevents oxidation by inactivating the enzymes in the leaves. Thus green and black teas have different chemical properties." (University)

"The growth bud and the first two or three leaves at the tip of the shoot produce the finest tea, while poorer quality tea is produced from material taken from lower down on the stem. Harvesting is still performed by hand in much of the world, as it takes discrimination to determine which are the best leaves." (Muir)

"Commercially prepared green tea extracts are standardized to contain 60% polyphenols and depending on the method of preparation, the tea may contain 1% to 4% caffeine." (Fetrow)

"When green tea is taken for medicinal purposes, 5-10 ml of the herb is steeped in a cup of boiling water for about 15 minutes. The usual amount taken is 1-3 cups daily, without the addition of milk or sugar. More recently, green tea capsules have been developed for the market, but the clinical benefits of these are unknown." (Kaegi)

"Green tea contains many polyphenols known as catechins, including epigallocathechin-3 gallate (EGCG), epigallocathechin (EGC) and epicathechin-3 gallate (ECG)." (Jankun)

History

"Much of the research into the effects of green tea has focused on its potential to prevent cancer. There has been far less research into its role in the treatment of cancer." (Kaegi)

Proponent / Advocate Claims - Use in Preventing Cancer

"Population studies demonstrate that green tea consumption may actually be one of the major reasons why the cancer rate is lower in Japan ." ( Murray )

"Drinking at least one cup of green tea per week appears to reduce the risk of stomach cancer." (Cassileth)

"Green tea polyphenols are potent antioxidant compounds that have demonstrated greater antioxidant protection than vitamins C and E in experimental studies. (Ho)" (Murray)

"A few studies have reported that green tea and green tea extracts reduce the metastatic potential of cancer cells in some animal systems. (Taniguchi, Sazuka) These findings, together with the evidence that green tea extracts suppress chromosomal abnormalities induced by carcinogens, have generated some interest because they suggest that green tea plays a role in delaying the cumulative genetic damage necessary for a cell to evolve from normalcy to one with aggressive metastatic capabilities." (Kaegi)

Suganuma reports "significant evidence that whole green tea is a more reasonable mixture of tea polyphenols for cancer prevention in humans than EGCG alone, and that it is even more effective when it is used in combination with other cancer preventatives." (Suganuma)

"There are several types of green tea that are grown under different climatic conditions and there is a likelihood of variability of anticancer constituents in different types of green tea." (Holt)

Proponent / Advocate Claims - Use in Treating Cancer

"In vitro [in an artificial environment] studies of green tea polyphenols induced programmed cell death (apoptosis) in human cancer cells. (Hibasami, Ahmad)" (Fetrow)

"Human cancers need proteolytic enzymes to invade cells and form metastases. One of these enzymes is urokinase (uPA). Inhibition of uPA can decrease tumour size or even cause complete remission of cancers in mice. ...we postulate that the well-known anticancer activity of green tea is driven by inhibition of uPA, one of the most frequently over-expressed enzymes in human cancers." (Jankun)

Some studies in mice demonstrated that "oral administration of green tea not only decreased tumor formation, but also markedly reduced tumor size. Further experiments showed that green tea inhibited the growth of established skin tumors induced chemically or by ultraviolet light." (Yang)

Recent studies suggest that theanine (a peculiar amino acid existing in green tea
leaves) enhances the antitumor activity of doxorubicin and adriamycin in mice. "The effect of theanine on the efficacy of antitumor agents is expected to be applicable in clinical cancer chemotherapy." (Sugiyama 1999,1998)

Professional Evaluation / Critique - Use in Preventing Cancer

"It must be recognized that the cancer-protective effect of green tea is only apparent at the relatively high intake of more than 10 cups per day." (Holt)

Professional Evaluation / Critique - Use in Treating Cancer

"There has been some laboratory research into the possible role of green tea in the treatment of cancer. However, no human studies and only limited data from animal studies were identified. In assay systems, the effects of green tea have been contradictory and inconclusive, showing both mutagenic and antimutagenic effects.(Nagao, Jain, Ito, Wang)" (Kaegi)

"However, Dr. Jankun believes that green tea will remain more useful for prevention than for treatment of cancer." (Muir)

"While important work in the laboratory continues to elaborate the mechanisms by which green tea inhibits cancer, the major missing link has been clinical trials. ... `We are trying to caution people that green tea is still very far from being a therapy. We are very much at the beginning of studying it." It is notable that the first clinical trials in the United States have not yet begun. ... Indeed, unfortunately, the history of medicine contains many examples of substances that looked extremely promising in both in vitro and animal studies, but never lived up to such promise in the clinical trials." (Muir)

"Also, before green tea can become widely used, more research will be needed regarding the efficiency of its absorption, its attainable blood levels, its metabolism, and its toxicity when taken in large quantities." (Muir)

Toxicity / Risks

"No adverse effects have been reported in association with the medicinal use of green tea. However, a cup of tea, black or green, contains 10-80 mg [milligrams] of caffeine depending on the methods used in its production, storage and preparation. Because excess caffeine can cause nervousness, insomnia and irregularities in heart rate, pregnant women, nursing mothers and patients with cardiac problems are usually advised to limit their intake to 2 cups daily." (Kaegi)

Green tea can cause adverse reactions (immunoglobulin E-mediated) in patients with green-tea asthma. (Fetrow)

A study done by Kinjo and associated concluded that mortality risks of oesophageal cancer were substantially associated with the thermal effects of hot green tea compared to moderate temperature tea. (Kinjo)

Revised February 2000

Green tea halts growth of oral cancer cells and breaks down and kills existing oral cancer.(1,2) Ingesting or swishing with green tea introduces the tea polyphenols to the oral cancer cells which may be present in the mouth. The polyphenols are antioxidants, which work to remove the free radicals (oxidants) which cause the mutation of genes, which may in turn lead to cancerous growth, without harming the normal cells Green tea halts growth of oral cancer cells and breaks down and kills existing oral cancer.(1,2) Ingesting or swishing with green tea introduces the tea polyphenols to the oral cancer cells which may be present in the mouth. The polyphenols are antioxidants, which work to remove the free radicals (oxidants) which cause the mutation of genes, which may in turn lead to cancerous growth, without harming the normal cells the growth and invasion of oral cancer cells. The authors state that the clinical applications of green tea polyphenols, including EGCG as an anti-cancer agent, warrant further study. They suggest that the regular consumption of green tea could be beneficial in the prevention of oral cancer.

The Benefits of Green Tea Extract: Anti-Aging, Anti-Cancer, Weight Control

One of the great advancements in nutrition in the twenty-first century is the scientific confirmation of the many benefits of green tea extract. Here are just a few. Green tea:
Lowers cholesterol
Slows arthritis
Prevents the growth of cancer cells
Assists weight loss
What accounts for the health benefits of green tea extract? Over 1,800 scientific studies have found that the active constituents in green tea are powerful antioxidants. These are called polyphenols (catechins) and flavonols. Epigallocatechin gallate (you can just call it EGCG) is the most powerful of these antioxidants. Milligram for milligram, EGCG has 25 to 100 times the antioxidant power of vitamins C and E. A cup of green tea has more antioxidants than a serving of broccoli, spinach, carrots or strawberries.

These abundant antioxidants power the benefits of green tea extract. They keep DNA intact and they stabilize the membranes of cells. These effects of green tea make it a powerful support in many health conditions. Let's look at the benefits of green tea supplements in more detail.

Green tea has been shown to lower "bad" LDL cholesterol and serum triglyceride levels.

Who would have imagined that simple green tea could be as potent as Lipitor or Zocor or Crestin with none of their side effects? Scientific studies show that middle-aged men and women in Japan who drink 2 or more cups of green tea a day almost always have normal cholesterol. Scientists have also recently reported that if you drink green tea after you eat a fatty food, less cholesterol will go into you bloodstream.

And if you have high cholesterol when you begin taking green tea supplements, your body will convert less of it into a form that clogs your arteries.

Green tea protects your joints against osteoarthritis.

This is one of the least known but most beneficial effects of green tea extract. Green tea prevents inflammation. When there is less inflammation, there is less wear and tear on your joints.

Green tea prevents the growth of cancer cells.

The EGCG in green tea prevents cancer cells from growing by binding to a specific enzyme. This health benefit of green tea is especially important in cancers of the prostate, breast, and lung.

Researchers studied two groups of men who a pre-cancerous condition of the prostate. One consumed the equivalent of 12 to 15 cups of green tea a day. One did not. One year later, 30% of the men who did not consume green tea supplements developed prostate cancer. Only 3% of the men who took green tea supplements developed cancer.

Another of the benefits of green tea extract is support for women who have breast cancer. Green tea provides chemicals that bind estrogen. This hormone is not then free to stimulate breast cancer cells.

Women who consume the greatest amount of green tea before menopause have the least severe forms of breast cancer when the disease occurs. Women who drink green tea are less likely to have recurrences of breast cancer after treatment. And most important of all, women who consume green tea are 50% less likely to develop breast cancer at all.

Another of the benefits of green tea extract is protection against lung cancer. The Japanese have both the highest rate of smoking and the lowest rate of lung cancer in the developed world. Japanese smokers who consume a lot of green tea seem to be protected against lung cancer.

And green tea can even help you lose weight. In a clinical trial, men eating a high-fat diet were given enough green tea provide the caffeine in a single cup of coffee. Although this amount of caffeine has no effect on weight loss, when the caffeine comes from green tea, it is highly significant.

The green tea supplement boosted the number of calories burned by 4.5%. While this is just 135 calories a day, the study showed that taking green supplements could help the average man on a high-fat diet lose 18 lbs (8 kg) in a year's time. It could help the average woman on a high-fat diet lose 11 pounds (5 kg). This is without eating less or exercising more.

How Can I Take Green Tea?

The benefits of green tea extract are greatest if you take green tea supplements rather than drink green tea. A study in the December 2004 edition of the American Journal of Clinical Nutrition confirmed that green supplements get more antioxidants into your bloodstream that drinking green tea. Two capsules of green tea extract a day can provide all the benefits of 20 cups of green tea-all you need to support even difficult health conditions.

Green tea is safe and effective. Take 1 to 3 capsules of green extract every day. It is better to take green tea supplements in the morning or afternoon rather than at night. In the unlikely event of stomach upset, take with food.
by Oktay Özadam