Cancer & the Health Benefits of Green Tea

One of the reasons why green tea is so potent against so many cancers is because it contains an exceptional blend of powerful anti-inflammatories and antioxidants. Green tea also has the remarkable ability to amplify the power of the enzymes in your liver that detoxify your body of poisons and carcinogens. Researchers believe that most of the healthy benefits of green tea come from substances within it called polyphenols. The three polyphenols considered most important are gallocatechin (GC), epigallocathechin (EGC), and epigallocatechin gallate (EGCG). Of the three, EGCG is the most potent.

-Waking the Warrior Goddess, Kristine Horner, M.D.

Breast Cancer
Japanese researchers found that among healthy women, those who drank green tea had a lower risk of breast cancer. And those women with breast cancer who drank green tea lived much longer than those who didn't. For instance, women with stage 1 or stage 2 breast cancer, who were green-tea drinkers before they were diagnosed, were found to have a much better prognosis for survival. Also, a 1998 study found that drinking green tea lowered the risk of breast tumors metastasizing and stopped them from recurring after the women had been treated.

Several studies show that EGCG inhibits the growth of breast cancer and decreases the incidence of its metastasizing to the lungs. A Japanese study of rats with mammary tumors found that 93.8 percent of the rats given green tea survived, compared to only 33 percent of the rats that weren't given green tea. The rats given green tea also had smaller tumors than those that weren't given it. 

Scientists have mapped out seven different ways in which green tea combats breast cancer. For one, it increases the number of protein binders in the blood and the more protein binders there are in the blood, the more estrogen it binds and the less estrogen there is available to attach to estrogen receptors in the breast. Green tea also lowers estradiol levels and increases the number of estrogen and progesterone sensitive receptors in breast cancers found in postmenopausal women. This is important, because tumors with the receptors sensitive to these hormones respond better to treatment and have a better prognosis.

This stellar brew also helps to block the growth of new blood vessels into the tumor - a quality that is technically referred to as antiangiogenic. If you ae on chemotherapy, green tea can enhance its effectiveness and at the same time protect against many of its dangerous side effects. Japanese researches T. Sugiyama and Y. Saduka published several studies between 1998 and 2003 showing that green tea and some of its individual components increase the concentration of chemotherapeutic agents, such as doxorubicin and Adriamycin, in tumors by 2.1 to 2.9 times, and decrease the levels of these drugs in normal tissue.

The results are that when you drink green tea while you're taking these chemotherapeutic drugs, tumors shrink more than they usually do without the green tea. In addition, organs that are commonly damaged by these anticancer drugs, such as the heart and liver, are protected from injury by drinking this potent green brew.

-Waking the Warrior Goddess, Kristine Horner, M.D.

How Do Green Tea Catechins Prevent Cancer?
They lower the toxicity of certain carcinogens, thereby reducing their cancer-causing potential. They interfere with the biding of cancer-causing substances to the DNA of healthy cells. They act as antioxidants, protecting the body against free radical damage.

They work together with antioxidants and enzymes in the small intestine, liver, and lungs to prevent tumors from starting. They inhibit tumor activation.

- Nadine Taylor, M.S., R.D., Green Tea, The Natural Secret for a Healthier Life, Kensington Health

Protects against Cancer - The Plant Kingdom's Arnold Schwarzenegger
In the last ten years, green tea's cancer-preventive effects have been widely supported by epidemiological, cell culture, animal and clinical studies. For cancer prevention, the evidence is so overwhelming that the Chemoprevention Branch of the National Cancer Institute has initiated a plan for developing tea compounds as cancer-chemopreventive agents in human trials.

When confronted with a cancerous cell, green tea becomes the plant kingdom's Arnold Schwarzenegger, helping to terminate cancer cells in a remarkable number of ways.

Laboratory cell culture studies show that green tea polyphenols are powerful triggers of apoptosis (cell suicide) and cell cycle arrest in cancerous but not in normal cells. (Cell cycling is the process cells go through to divide and replicate.)

These anticancer actions have been assumed to be due to the powerful antioxidant effects of green tea's catechins, especially epigallocatechin-3-gallate (EGCG). This is a reasonable assumption, given that a number of studies have shown that green tea possesses remarkable antioxidant properties. In one study published in the November 2004 issue of Mutation Research, EGCG's protective antioxidant effects against several carcinogens were found to be 120% stronger than those of vitamin C.

But while green tea's antioxidant prowess is impressive, recent studies show it is far from the only way in which this multi-talented beverage protects us against cancer.

One of these mechanisms is green tea's ability to inhibit angiogenesis, the development of new blood vessels. Cancer cells, which are constantly attempting to divide and spread, have an endless appetite that can only be temporarily quieted by increasing the number of blood vessels that supply them with nutrients. By inhibiting angiogenesis, green tea helps starve cancer.

Studies also show that green tea works at the genetic level, shutting off genes in cancerous cells that are involved in cell growth, while turning on those that instruct the cancer cells to self-destruct. EGCG has even been found to work as a pro-oxidant or free radical, but just inside cancer cells, where it causes so much damage that the cancer cells' self-destruct mechanisms are triggered.

A study of ECGC's effects on keratinocytes (the major type of epidermal or skin cell) found that this green tea compound has yet another means of correcting cancer-that of turning on the genes that direct the cancer cell to return to normal.

Green tea's anticancer effects include its ability to inhibit the overproduction of the enzyme cyclooxygenase (COX)-2, a protein whose overproduction has been implicated as a factor in many diseases, including arthritis and cancer. COX-2 has an enzyme counterpart, called COX-1, which may be helpful to leave untouched when preventing overproduction of COX-2. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen (which inhibit both COX-1 as well as COX-2), and specific COX-2 inhibitors such as Vioxx and Celebrex (which inhibit only COX-2), have been considered as possible agents in the prevention of some forms of cancer, but their severe toxic side effects on normal cells limit their usefulness. In studies of prostate cancer cells, EGCG appears to block only COX-2 and to have no negative side effects.

Phytonutrients in green tea, specifically, its catechins, increase the production and activity of detoxification enzymes in humans, and may enhance our ability to detoxify carcinogens, shows research supported by the National Cancer Institute.

42 healthy volunteers refrained from tea or tea-related products for one month, after which blood samples were taken to assess the activity and levels of their glutathione S-transferases (GST), a major group of detoxification enzymes. Volunteers then consumed green tea catechins in amounts equivalent to consuming between 8-16 cups of green tea each day. GST activity was greatly enhanced in those whose baseline GST activity was low-those most susceptible to damage from carcinogens. (Chow HH, Hakim IA, et al.,Cancer Epidemiol Biomarkers Prev.)

Understanding How Green Tea Fights Cancer
Spanish and British scientists have discovered at least one of the mechanisms through which green tea helps to prevent certain types of cancer, according to a study published in the March 2005 issue of Cancer Research.

ECGC, a catechin present in green tea in amounts about 5 times higher than in black tea, inhibits the enzyme dihydrofolate reductase (DHFR), which cancer cells need to be able to grow, and which is a well recognized target of anti-cancer drugs.

Scientists decided to look at ECGC after they realized the green tea catechin looks a lot like the cancer drug methotrexate, which prevents cancer cells from making DNA by inhibiting the DHFR enzyme. They discovered that ECGC kills cancer cells in the same way as the drug.

Although ECGC binds strongly to DHFR, which is essential in both healthy and cancerous cells, it does not bind as tightly as methotrexate, so its side effects on healthy cells are less severe than those of the drug.

-www.whfoods.org

Killing Leukemia Cells
Testing by the Mayo Clinic has discovered that the EGCG helps kill leukemia cells by interrupting the nourishing blood flow to the cancer cells, leaving the cancer cells to 

- Green Tea, Mary Lou Heiss, The Harvard Common Press

Researchers from the Mayo Clinic in Rochester, Minnesota, examined the interaction between EGCG from green tea and cancer cells taken from 10 patients diagnosed with the most common type of leukemia: B-cell chronic lymphocytic leukemia (CLL).

This research also involved a receptor cell, called VEGF, which nurtures growth in leukemia. Researchers found that EGCG suppressed the VEGF mechanism, inhibiting the growth of new blood vessels necessary for cancer proliferation. In 8 of the 10 samples, EGCG prompted the death of cancer cells.

The Mayo Clinic researchers hope their study will eventually lead to a non-toxic way to treat CLL. This type of leukemia can only be treated with chemotherapy, but when older patients are diagnosed with early stages of CLL (a cancer that mostly affects people over the age of 60), some doctors choose to monitor the slow-growing disease before subjecting a patient to unnecessary (and harsh) treatments. The Mayo team believes that EGCG could be an effective, low-impact treatment for early stage CLL. - Reported by Health Sciences Institute

-Science News, Apr 12, 2003  (Click here to compare matcha powder & sencha powder)

Green Tea as a Potential Cancer Therapy
The ability of green tea to prevent cancer is so well established that new studies are testing green tea as a potential cancer therapy. Green tea may be especially protective against lung cancer in former and current cigarette smokers. Its lung cancer protective effects are of significant importance based on new studies showing that former smokers are at greater risk for developing lung cancer than was previously thought.

Green tea catechins have been shown to prevent cancer in the following ways:

• They help to neutralize dietary carcinogens such as nitrosamine and aflatoxin.
• They interfere with the binding of cancer-causing agents to cellular DNA, thereby protecting cells against mutations that can eventually cause cancer.
• They protect against free-radical DNA damage that causes some cancers.
• They inhibit bacterial-induced DNA mutations that also can lead to certain cancers.
• They work with enzymes and other antioxidants in the intestine, liver and lungs to prevent the activation of certain carcinogens before they damage DNA.
• They protect against the effects of ionizing radiation and ultraviolet radiation.

Green tea has been shown to counteract both the initiation and promotion of carcinogenesis. Some studies have shown that green tea blocks the formation of certain tumors. If green tea's only benefit were to reduce the risk of cancer, it would be well worth taking as a beverage or supplement.

-lef.org

Antioxidants in Green Tea Helpful for Cancer 
Preliminary studies have suggested that antioxidants are useful in a number of ways in regards to cancer. For instance, they may improve the effectiveness of chemotherapy, decrease side effects of chemotherapy and radiotherapy, and prevent some types of cancer. Sufficient epidemiological studies have shown that ingesting foods high in antioxidants, such as fruits and vegetables, can decrease the risk of many types of cancer. Studies also found that cancer patients have lower levels of anti-oxidants in their blood.

Green Tea & Cancer Prevention
Michael Murry, M.D. explains "Green tea is produced by lightly steaming the fresh cut tea leaf. To produce black tea, the leaves are oxidized. During oxidation, many of the polyphenol substances, compounds with potent antioxidant and anticancer properties, are destroyed. Unlike black tea, green tea is very high in polyphenols."

Green Tea & Polyphenol Block
The anticancer effects are the result of green tea polyphenols blocking the formation of cancer causing compounds as well as effectively detoxifying or trapping cancer causing chemicals.

Green Tea & Cancer Prevention
The forms of cancer that green tea shows the most aid in preventing are cancers of the gastrointestinal tract such as cancer of the stomach, small intestine, pancreas, and colon. Also, green tea has shown preventative properties for lung cancer and estrogen-related cancers such as most breast cancers. A report from the National Cancer Institute found that Chinese men and women who drink green tea have a reduced risk of developing esophageal skin cancer.

Green Tea Protects Against Cancer
Several population-based studies have shown that green tea helps protect against cancer. For example, Cancer rates tend to be low in countries such as Japan where people regularly consume green tea. However, it is not possible to determine from these population-based studies whether green tea actually prevents Cancer in people. Emerging studies suggest that the polyphenols in green tea may play an important role in the prevention of cancer. Researchers also believe that polyphenols help kill cancerous cells and stop their progression.

-University of Maryland Medical Center

Green Tea & Bladder Cancer
Only a few studies have examined the relationship between bladder cancer and green tea consumption. In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up study by the same group of researchers revealed that bladder cancer patients (particularly men) who drank green tea had a substantially better 5-year survival rate than those who did not. 

-University of Maryland Medical Center

Green Tea & Breast Cancer
Studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who consumed the most green tea experienced the least spread of cancer (particularly premenopausal women in the early stages of breast cancer). They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to suffer recurrences of the disease after completion of treatment. However, women with late stages of breast cancer experienced little or no improvement from drinking green tea. In terms of breast cancer prevention, the studies are inconclusive. 

-University of Maryland Medical Center

Green Tea & Ovarian Cancer
 In a study conducted on ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day survived longer with the disease than those who didn't drink green tea. In fact, those who drank the most tea, lived the longest.

-University of Maryland Medical Center

Green Tea & Colorectal Cancer
Studies on the effects of green tea on colon or rectal cancer have produced conflicting results. Some studies show decreased risk in those who drink the tea, while others show increased risk. Further research is needed before researchers can recommend green tea for the prevention of colorectal cancer.

- University of Maryland Medical Center

Green Tea & Esophageal Cancer
Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells. However, studies in people have produced conflicting findings. For example, one large-scale population-based study found that green tea offered significant protection against the development of esophageal cancer (particularly among women). Another population-based study revealed just the opposite -- green tea consumption was associated with an increased risk of esophageal cancer. In fact, the stronger and hotter the tea, the greater the risk. Given these conflicting results, further research is needed before scientists can recommend green tea for the prevention of esophageal cancer.

- University of Maryland Medical Center

Green Tea & Lung Cancer
While green tea polyphenols have been shown to inhibit the growth of human lung cancer cells in test tubes, few studies have investigated the link between green tea consumption and lung cancer in people and even these studies have been conflicting. One population-based study found that Okinawan tea (similar to green tea but partially fermented) was associated with decreased lung cancer risk, particularly among women. A second study revealed that green tea and black tea significantly increased the risk of lung cancer. As with colon and esophageal cancers, further studies are needed before researchers can draw any conclusions about green tea and lung cancer.

- University of Maryland Medical Center

Green Tea May Help Prevent Lung Cancer  
On Long Island, researchers have found that a critical class of green tea compounds may prevent lung cancer. Dr. Theodore Gabig, chief of hematology and oncology at Stony Brook University Hospital said tea leaves contain a motherlode of beneficial compounds. But pursuing tea-related research, he added, is not a simple enterprise.

-Mail Tribune, October 2007

Green Tea & Pancreatic Cancer
In one large-scale study researchers compared green tea drinkers with non-drinkers and found that those who drank the most tea were significantly less likely to develop pancreatic cancer. This was particularly true for women -- those who drank the most green tea were half as likely to develop pancreatic cancer as those who drank less tea. Men who drank the most tea were 37% less likely to develop pancreatic cancer. However, it is not clear from this population-based study whether green tea is solely responsible for reducing pancreatic cancer risk. Further studies in animals and people are needed before researchers can recommend green tea for the prevention of pancreatic cancer. - University of Maryland Medical Center

Green Tea & Prostate Cancer
Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large study conducted in Southeast China researchers found that the risk of prostate cancer declined with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. Given this potential interaction, people should not drink black and green tea (as well as extracts of these teas) while receiving chemotherapy.

-University of Maryland Medical Center

Green Tea & Skin Cancer
The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anti-cancer properties that may help prevent the onset and growth of skin tumors.

- University of Maryland Medical Center

Two Stages of Cancer Prevention with Green Tea
This is a research review paper on benefitial effects of green tea. (1) introduced the present status (1999) of clinical trials cancer prevention with green tea supported by the Chemoprevention Branch of the National Cancer Institute in the United States. (2) evidences of cancer prevention with green tea at gene level and cohort studies with over 8000 individuals. (3)for cancer treatment: to delay cancer onset, (green tea diet) at least 10 cups of green tea per day, for recurrence rate of stages I and II breast cancer patients, consumming 5 cups of green tea per day is lower than those taking less than 4 cups per day. (4)two-stage approach to analyzing cancer prevention with green tea is proposed.

-J Cancer Res Clin Oncol 1999 Nov;125(11):589-97 

Green Tea Consumption and the Risk of Pancreatic and Colorectal Cancers
Benefits of gren tea in cancer prevention was examined via a large population-based case-control study, with cases of 931 colon cancer, 884 rectum cancer, 451 pancreas cancer, and 1552 controls in Shanghai, China. An inverse association with each cancer was observed with increasing amount of green tea consumption, with the strongest trends for rectal and pancreatic cancers. For men, compared with non-regular tea drinkers, odds among those in the highest tea consumption category (green tea diet, > or = 300 g/month) were 0.82 for colon cancer, 0.72 for rectal cancer and 0.63 for pancreatic cancer. For women, the respective odds for the highest consumption category (green tea diet > or = 200 g/month) were 0.67, 0.57 and 0.53. The findings provide further evidence that green tea drinking may lower the risk of colorectal and pancreatic cancers

-Int J Cancer. 1997 Jan 27;70(3):255-8

Reduced Risk of Esophageal Cancer Associated with Green Tea Consumption
A case-control study of 902 patients and 1552 control subjects found: statistically significant decreases in risk of esophageal cancer among tea drinkers were observed for both men (odds ratio = 0.43) and women (odds ratio = 0.40). 

-Source: J Natl Cancer Inst. 1994 Jun 1;86(11):855-8 

Green Tea Constituent Epigallocatechin-3-Gallate
Experiments of effects of green tea component EGCG on human liver cancer cell line Hep G2 found: EGCG inhibited the proliferation of Hep G2. Suggest a mechanism for benefit of green tea in liver cancer prevention. 

-Source: J Biomed Sci. 2003 Mar-Apr;10(2):219-27 

Green Tea Reduces Alcohol & Cigarette Induced Cancer Rates 
A case-control study on drinking green tea and decreasing risk of cancers in the alimentary canal among cigarette smokers and alcohol drinkers
A population based case-control study on benefit of green tea in prevention of gastric cancer, liver cancer, esophageal cancer among alcohol drinkers or cigarette smoker. Cancer cases: stomach - 206, liver - 204, esophageal - 218. Found: among alcohol drinkers, green tea drinking decreased risk of cancers: stomach - 81%, liver - 78%, esophageal - 39%; among cigarette smokers: stomach - 16%, liver - 43%, esophageal - 31%.(Article in Chinese) 

-Source: Zhonghua Liu Xing Bing Xue Za Zhi (Chinese Journal of Epidemiology). 2003 Mar;24(3):192-5

Lung Cancer and Green Tea Consumption Among Women Living in Shanghai, China
Epidemiologic study of 1324 women lung cancer patients (649) and contral group (675) found benefits of green tea consumption: Among nonsmoking women, consumption of green tea was associated with a reduced risk of lung cancer (OR = 0.65; 95% CI = 0.45-0.93), and the risks decreased with increasing consumption. 

-Source: Epidemiology. 2001 Nov;12(6):695-700

EGCG as a Chemo Preventive & Therapeutic Agent 
Epigallocatechin-3-gallate is a potent natural inhibitor of fatty acid synthase in intact cells and selectively induces apoptosis in prostate cancer cells
Green tea component EGCG was shown to act as a natural inhibitor of fatty acid synthase (FAS), and to selectively cause apoptosis in prostate cancer cells but not in nontumoral fibroblasts. The findings establish EGCG as a potent natural inhibitor of FAS in intact cells and strengthen the molecular basis for the use of EGCG as a chemopreventive and therapeutic antineoplastic agent 

-Int J Cancer. 2003 Oct 10;106(6):856-62 

Protective Effect of Green Tea Against Prostate Cancer
A case-control study on protective effect of green tea against prostate cancer was carried out. Total of 404 patients were studied, among them, 130 cases of prostate cancer and 274 hospital inpatients without prostate cancer as contral group. Significant benefit of green tea against prostate cancer was found. The longer, and the more one drinks green tea, the less risk of getting prostate cancer. The odds ratio was 0.27 for those (green tea diet) drinking more than 3 cups (1 litre) of green tea daily compaired to non-tea drinkers, suggesting that green tea is protective against prostate cancer. 

-Int J Cancer. 2004 Jan 1;108(1):130-5

EGCG in Green Tea
Radiation induced-tubulogenesis in endothelial cells is antagonized by the antiangiogenic properties of green tea polyphenol (-) epigallocatechin-3-gallate. 

The study of green tea benefits shown: Pretreatment of the cells with green tea extract epigallocatechin-3-gallate (EGCg), a green tea catechin that possesses anti-angiogenic properties, prevented most of the ionizing radiation (IR)-induced cellular and molecular events. 

-Cancer Biol Ther. 2003 Nov-Dec; 2(6): 642-9 

EGCG in Green Tea & Leukemia Cells
VEGF Receptor Phosphorylation Status and Apoptosis is Modulated by a Green Tea Component, Epigallocatechin-3-gallate (EGCG) in B cell Chronic Lymphocytic Leukemia 

Benefits of green tea to health are beyond chemoprevention. Green tea can kill cancer cells. The study demonstrated: Component of green tea extract, epigallocatechin-3-gallate (EGCG), destroys leukemia cells by interrupting the communication signals they need to survive. 

-Source: Blood. 2004 Mar 2 

Decreased Cancer Incidence with Green Tea Consumption
The epidemiological study with 8552 general residents in Japan revealed: drinking green tea (1) decreased relative risk of cancer incidence by 43~46%. (2)decreased relative risk of death from cardiovascular disease by 28%. (3)the benefits of decreased risks were for those consuming (green tea diet) over 10 cups a day, compared with those consuming below 3 cups

-Biofactors. 2000;13(1-4):49-54

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