Composition Of Green Tea
Most researchers point to the chemical composition of green tea as the main driver behind its health benefits . Green tea is composed of polyphenols, amino acids, minerals, proteins, and carbohydrates. Tea polyphenols tend to be the main actors in green tea’s health benefits. These green tea polyphenols contain subcategories including catechins and flavonoids. The most active tea catechins are epigallocatechin , epigallocatechin-3 and epigallocatechin gallate . Green tea contains 25 to 106 mg per 8 ounces of EGCG, the most researched tea polyphenol when it comes to cancer prevention .
The amount of polyphenols and other healthy tea constituents depends largely on how the tea is brewed . Brewing green tea with more leaves results in higher concentrations of polyphenols. Instant and iced teas tend to have less polyphenols due to temperature changes as well as quality of the tea leaves. Decaffeinated teas also have fewer polyphenols than natural green teas. Brewing green tea above 180 F can also damage the tea polyphenols, rendering them less effective.
Delayed Cancer Onset Revealed By 10
Nakachi and Imai found a total of 419 cancer patients, 175 females and 244 males, during 10 years, from a survey living habits of 8,552 individuals aged over 40 living in Saitama Prefecture, including their daily consumption of green tea . They reported that cancer onset in female patients who had consumed over 10 Japanese-size cups of green tea per day was 7.3 years later than that of patients who had consumed less than three cups per day . The difference between females and males may be partly due to higher tobacco consumption by males. Consuming over 10 cups of green tea per day also significantly prevented lung cancer, with a relative risk of 0.33, followed by cancers of the colorectum, liver and stomach, in that order . Results of two research groups: Green tea catechins at 600 mg per day were effective for treating premalignant lesions before prostate cancer development, research conducted at University of Parma, Italy : and green tea extract showed preventive effects on oral premalignant leukoplakia in patients, at the University of Texas M.D. Anderson Cancer Center .
Prevention Of Colorectal Adenoma Recurrence With 10 Japanese
The Saitama Prefectural Tea Research Institute began to produce tablets of green tea extract , which is the dried form of green tea beverage. One tablet is equivalent to approximately 2 Japanese-size cups of green tea. One hundred two healthy citizens of Saitama Prefecture joined the preclinical safety trial of G.T.E, with informed consent. The blood examination did not show any serious effects, and 93% of the participants were able to continue drinking green tea beverage and also taking G.T.E . Because some of the subjects had very mild temporary disorders, the Tea Research Institute subsequently reduced the caffeine content of the tablets from 5% to less than 3% without using an organic solution.
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The Role Of Beverages In Diet
Dr. Mario Ferruzzi, professor and chief of the section of Developmental Nutrition in the Department of Pediatrics at the University of Arkansas for Medical Sciences, touched on teas place in current dietary guidelines.
Currently, dietary bioactive compounds like flavan-3-ols are not part of food-based dietary guidance. Polyphenols make up 30 to 40 percent of the solids in a cup of green and black tea. The dietary guidelines have mentioned phytochemicals as a beneficial part of fruit and vegetables, but not beverages.
To rectify these shortcomings, Dr. Feruzzi noted that current guidelines on healthy beverages need to be expanded to include tea and coffee as a source of bioactive components, such as flavonoids.
Moreover, dietary guidelines should include an adequate intake value for dietary flavonoids to ensure sufficient intake of these nutrients that can help reduce the risk of chronic diseases.
Dr. Feruzzi cautioned that ready-to-drink products tend to have lower levels of flavonoids, and hence, consumers should favor brewed tea over these products.
Tea Types And Flavonoids
Tea is the second most consumed beverage in the world, after water. The four primary types of tea include white, green, Oolong, and black. All four teas are derived from the same plant, Camellia sinensis, but differ in how they are processed after harvesting.
Tea contains a wide array of components that have biological activity, including flavonoids, L-theanine, and caffeine. Many of the beneficial effects of tea are due to the high levels of flavonoids, such as catechins, which have antioxidative and anti-inflammatory properties.
The differences in the manufacturing process can influence the chemical composition and the beneficial effects of the different tea types. For instance, green tea is roasted before it can oxidize and hence, contains
A number of observational studies suggest that tea consumption is associated with improvements in cognitive function. A few small randomized controlled trials have suggested tea intake may result in short-term improvements in attention.
Each cup of tea contains about of caffeine, which may contribute to the increase in attention and improvements in mood some people experience after consuming tea. Tea also contains theanine, which has been suggested to enhance attention while reducing anxiety and stress.
The flavonoids present in tea may also exert protective effects against common age-related cognitive decline and dementia. Dr. Jonathan Hodgson, a professor at the University of Western Australia, told Medical News Today:
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Cancer Stem Cells In Mouse Skin Carcinogenesis
EGCG and green tea extract inhibit the growth of human cancer cell lines in culture and in rodents . Since inhibition of tumor promotion by EGCG is assumed to be strongly related to the non-toxic downregulation of CSCs, we gathered numerous reports from a search of PubMed and published our review article of the literature to provide a broad selection for the effects of EGCG on about 20 human CSCs enriched from cancer cell lines . In the next section, the expression of stemness markers in colorectal and nasopharyngeal CSCs will be introduced as examples, followed by the decrease or increase in stemness markers of human breast, lung and colorectal CSCs by EGCG.
Green Tea And Metastasis Of Liver Cancer
Hepatocellular carcinoma is a growing health problem worldwide and only few promising treatment options are available at present, stressing the urgent need for novel therapeutic approaches. The effect of a nutrient mixture containing lysine, proline, arginine, ascorbic acid, and green tea extract on tumor growth and hepatic metastasis were investigated in athymic nude male mice inoculated with 10 B16FO melanoma cells. Metastasis was studied in C57BL/6 mice receiving melanoma cells by intrasplenic injection, as well as a regular or 0.5% nutrient mixture-supplemented diet for 2 weeks. Nutrient mixture inhibited the growth of melanoma cells, and the lesions were consistent with malignant melanoma. Mice were also injected with melanoma cells in the spleen. Control group animals developed large black spleens and livers indicating growth in the spleen and metastasis to the liver, while mice supplemented with nutrient mixture showed less growth in spleen and reduced metastasis to the liver. The survival time was also greater in mice receiving nutrient mixture supplementation than animals on the regular diet .
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Side Effects Of Green Tea
Green tea usually is safe to drink, but you should be cautious about consuming large amounts of caffeine. Too much caffeine can lead to difficulty sleeping, headaches, and feeling jittery or shaky.
Additionally, large amounts of EGCG can cause some people to experience sickness or stomach aches. Particularly large quantities can be toxic to the liver. EGCG can also reduce the effects of other medications.
Why People With Cancer Use It
There is no real evidence that green tea can help treat cancer.
There is some evidence from early studies to suggest that having green tea might reduce the risk of some cancers. But at the moment the evidence is not strong enough to know this for sure.
People with cancer also drink green tea because they believe it might:
- boost their immune system which might help them fight their cancer
- improve health, energy levels and well being
- get rid of toxins in the body
- give them some control over their cancer and its treatment
- treat their cancer if no other conventional treatment can
The media has also promoted black tea as an anti cancer agent. Black tea comes from the same plant as green tea. But black tea is made from the fermented leaves of the plant.
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Benefits Of Green Tea For Breast Cancer
There is no specific evidence that green tea is effective in treating cancer. However, evidence shows that green tea may reduce the risk of developing certain cancers in people. Preliminary studies have also shown that green tea is effective in stopping the growth of cancer cells in some animals.
Green tea has positive benefits on overall health, which is one reason that many breast cancer patients drink it. Other reasons that people with cancer choose to drink green tea include the following beliefs:
- It will boost their immune system
- It may treat cancer if nothing else is working
- It will rid toxins from the body
- It will improve their energy levels
Green Tea Treatments And Research Findings
In a study from the Louisiana State University Health Sciences Center involving patients with prostate cancer, it was shown that green tea seems to help fight the disease in the early stages before it has spread. The green tea seemed to reduce the growth rate of tumors to a noticeable degree. It seems to be most effective in the early stages of prostate, breast, and lung cancer.
The men who participated in the prostate cancer study were asked to drink six cups of green tea each day. Those who did so were found to have much lower levels of prostate-specific antigen, which is an agent that causes tumors to grow.
In a study at the Columbia University Medical Center, a study was run where women with breast cancer were given green tea polyphenols. These chemicals actually lowered the rate of tumor growth over a period of two months. As the study went on, the scientists tried to determine the optimum amount of tea for maximum beneficial effect. They believed that 6-8 cups of green tea per day achieves optimal results.
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Antioxidants May Lower The Risk Of Some Cancers
Cancer is caused by uncontrolled growth of cells. Its one of the worlds leading causes of death.
Research has shown that oxidative damage can lead to chronic inflammation, which can lead to chronic diseases, including cancers. Antioxidants can help protect against oxidative damage .
Green tea is an excellent source of powerful antioxidants.
Research has linked green tea compounds with a reduced risk of cancer, including the following studies:
- Breast cancer. A comprehensive review of observational studies found that women who drank the most green tea had an approximately 2030% lower risk of developing breast cancer, one of the most common cancers in women (
- 23 ).
Many observational studies indicate that green tea drinkers are less likely to develop several types of cancer, but more high quality research is needed to confirm these effects .
To get the most health benefits, avoid adding milk to your tea. Some studies suggest it can reduce the antioxidant value in some teas .
Summary
Green tea has powerful antioxidants that may protect against cancer. Multiple studies show that green tea drinkers have a lower risk of various types of cancer.
Green Tea And Metastasis Of Skin Cancer
EGCG dose-dependently inhibited B16-F3m melanoma cell migration and invasion and inhibited the spread of melanoma cells on fibronectin, laminin, collagen, and Matrigel in a dose-dependent manner. EGCG significantly inhibited the tyrosine phosphorylation of focal adhesion kinase and the activity of MMP-9. EGCG also caused reduction in the lung metastases in mice bearing B16-F3m melanomas, but a combination of EGCG and dacarbazine was more effective than EGCG alone in reducing the number of pulmonary metastases and primary tumor growths and in increasing the survival rate of melanoma-bearing mice . EGCG and ECG were found to inhibit melanoma cell adhesion in the culture medium. The adhesion of murine melanoma cells to laminin was impaired on pretreatment with EGCG . EGCG significantly upregulated the expression of E-cadherin time and concentration dependently in human malignant melanoma A375 cell line. EGCG inhibited the invasion of human malignant melanoma cell line which correlated with the upregulation of E-cadherin expression .
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Bladder Cancer Treatment And Prevention Strategies Based On Green Tea Consumption
Epirubicin is an effective anticancer agent for bladder cancer. Epirubicin reportedly induces this cytoprotective autophagy in bladder cancer cell lines . Interestingly, GTPs inhibited epirubicin-induced autophagy and promoted apoptosis in the same study . Accordingly, it was suggested that GTPs can be used in combination with epirubicin for enhanced epirubicin-based bladder cancer therapy.
Discrepancies in findings regarding the anticancer effects of green tea between epidemiological studies and in vitro studies can be attributed to differences in the concentration of the GTPs used among studies. The concentration of GTPs used in in vivo studies is routinely lower than that used in in vitro studies . In one study, patients with prostate cancer received polyphenon E, which is derived from a hot water extract of green tea leaves and contains 8595% catechins, including EGCG, for 36 weeks before surgery. However, GTP levels in the prostatectomy tissue were low to undetectable . In addition, in a phase II randomized double-blind trial of bladder cancer, polyphenon E or placebo was administered prior to transurethral resection or radical cystectomy, following which tissue EGCG levels were compared between the experimental and placebo groups there was no significant difference between the two groups . On the basis of these findings, several investigators have shown interest in new technologies and methods that can achieve higher concentrations of GTPs in cancer tissues.
Green Tea And Metastasis Of Lung Cancer
Lung cancer is the most common cancer in the world and represents a major public health problem. The preventive effect of green tea catechins intake on lung tumor metastasis was examined in senescence-accelerated mice prone 10. Green tea catechins intake increased natural killer cell activity, which is an indicator of immune surveillance potential and was reduced in control group mice with age. Mice were given intravenous injection of the melanoma cells and the early accumulation of lung-metastatic K1735M2 melanoma cells and the subsequent experimental lung metastasis was investigated after treatment with green tea catechins. The accumulation at 6 and 24 h after injection of melanoma cells and the number of lung-metastatic colonies were significantly reduced in mice treated with green tea catechins as compared to mice in control group suggesting that green tea catechin intake prevented the experimental tumor metastasis in aged SAMP10 mice via inhibition of the reduction in immune surveillance potential with age . The effect of cytokines, mitogens, and inhibitors on MMP-2 and -9 expressions in human lung cancer A549 cells malignant melanoma MSTO-211H cells was investigated. EGCG inhibited MMP-2 and -9 expressions in both cell lines . It has been shown that EGCG had an inhibitory effect on bronchial tumor cells migration in 2D and 3D cell culture models. Treatment with EGCG also inhibited MMP-2 mRNA and protein expression and altered the intermediate filaments of vimentin .
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Treating Prostate Cancer With Green Tea
Written By Michael Greger M.D. FACLM on January 23, 2020
Green tea has been natures defense against cancer. Population studies linking green tea consumption with lower cancer risk have led some to advocate for the incorporation of green tea into the diet so as to fully benefit from its anticarcinogenic properties. What, after all, is the downside?
But, population studies cant prove cause and effect. Indeed, it is not possible to determine from these population-based studies whether green tea actually prevents cancer in peopleuntil it is put to the test.
What if you already have prostate cancer? A proprietary green tea extract supplement was given to 26 men with confirmed prostate cancer for an average of about a month before they had their prostates removed, and there was a significant reduction in a number of cancer biomarkers such as PSA levels, suggesting a shrinkage of the tumor. However, there was no control group, and the study was funded by the supplement company itself. When an independent group of researchers tried to replicate the results in a randomized, double-blind, placebo-controlled trial, they failed to find any statistically significant improvement. Perhaps green tea is only effective in the precancerous state and not powerful enough to meaningfully impact overt prostate cancer?
What happens if we pack our diet with all sorts of plant foods? See my Cancer Reversal Through Diet? video.
Use For Breast Cancer Prevention
Many studies have looked at the role of green tea and breast cancer prevention. Not all of them have found an association between drinking green tea and lower breast cancer risk, but some of the largest, most credible studies have.
In the Prostate, Lung, Colorectal, and Ovarian Screening Trial, which included more than 100,000 people, researchers found that those who consumed green tea had a lower overall risk of cancer in other words, it appeared to reduce the risk of any cancer. Whereas some studies have looked at very large amounts of green teasay, drinking 30 cups dailythis study looked at people who drank just one daily cup of green tea.
A 2017 study looked at breast density in women given a supplement of EGCG for one year. High breast density is linked with an elevated risk of breast cancer. While the supplement didn’t change breast density in older women, it significantly decreased it in young women. The effect was similar to that of tamoxifen, a drug that’s sometimes used to reduce the risk of breast cancer in high-risk individuals.
The researchers concluded that further studies should be done on the role of green tea in reducing breast cancer risk in young women.
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