Green Tea / EGCG


Nancy Hepp, MS, BCCT Project Manager

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Laura Pole, RN, MSN, OCNS, BCCT Senior Researcher

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Last updated June 9, 2021.

Also known by these names

  • Chinese tea
  • Matcha tea
  • Green tea extract
  • Green tea polyphenols
  • Epigallocatechin gallate (EGCG)

Key Points

  • Before using this therapy, consult your oncology team about interactions with other treatments and therapies. Also make sure this therapy is safe for use with any other medical conditions you may have.
  • The active constituent in green tea is epigallocatechin-3-gallate (EGCG).
  • BCCT’s interest in green tea and EGCG derives from its protective qualities. Evidence, especially from China, suggests that green tea may protect against cancers of the colon and stomach.
  • Some evidence shows that green tea’s relatively weak anticancer activity increases in combination with anticancer drugs.
  • Drinking green tea appears safe at regular, habitual and moderate use.
  • Green tea use may not be compatible with some conditions and circumstances.

The active constituent in green tea is epigallocatechin-3-gallate (EGCG). The medical effects of drinking green tea have been better studied than those from taking green tea extract or EGCG supplements.

Treating the Cancer

Working against cancer growth or spread, improving survival, or working with other treatments or therapies to improve their anticancer action

Clinical Evidence

Colorectal Cancer

  • Enhanced chemotherapy effects and outcomes: reduced disease progression rate, incidence of adverse events (at least grade 4) and occurrence of increased serum creatinine (an indicator of kidney toxicity) with use of B-6—a combination of fermented soybean extract, green tea extract, Antrodia camphorata mycelia, spirulina, grape seed extract, and curcumin extract—in people with metastatic colorectal cancer when combined with leucovorin, 5-fluorouracil, and oxaliplatin compared to chemotherapy alone1

Head, Neck and Oral Cancers

  • Reduced lesion size after six months among people with oral leukoplakia (premalignant lesions) taking capsules containing green tea extract, green tea polyphenols and black tea polyphenols  compared to those taking a placebo.2


  • Some indications of response were found in case studies and a small uncontrolled clinical trial of EGCG use by patients with chronic lymphocytic leukemia.3

Lung Cancer

  • No objective tumor responses were found at the maximum tolerated dose in preliminary studies of lung cancer patients.4

Ovarian Cancer

  • Dramatically improved five-year overall survival and progression-free survival, with fewer cancer relapses with ascites, among people with advanced ovarian cancer taking indole-3-carbinol (I3C) or both I3C and EGCG (green tea extract) during treatment with combined surgery and adjuvant platinum-taxane chemotherapy, both with and without neoadjuvant platinum-taxane chemotherapy5

Prostate Cancer

  • Reduced serum levels of PSA, HGF, and VEGF in men with prostate cancer, with no elevation of liver enzymes in men with positive prostate biopsies and scheduled for radical prostatectomy6
  • A trend toward beneficial changes in serum PSA and other markers of metabolic and oxidative status, plus a decrease in Gleason score from biopsy to surgery in men with prostate cancer scheduled to undergo radical prostatectomy7
  • No or minimal clinical activity against hormone refractory prostate cancer in a small study8

Lab and Animal Evidence

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Managing Side Effects and Promoting Wellness

Managing or relieving side effects or symptoms, reducing treatment toxicity, supporting quality of life or promoting general well-being

  • Improved quality of life, but with no differences in chemotherapy adverse events among people with advanced ovarian cancer taking indole-3-carbinol (I3C) or both I3C and EGCG (green tea extract) during treatment with combined surgery and adjuvant platinum-taxane chemotherapy, both with and without neoadjuvant platinum-taxane chemotherapy32
  • No effect reducing radiation therapy-induced nausea and vomiting in a review of several observational and one randomized trials33

Reducing Risk

Reducing the risk of developing cancer or the risk of recurrence

Clinical Evidence

Moderate evidence shows decreased risk of several cancer types with increased consumption of green tea.

Moderate evidence shows decreased risk in several cancer types, but increased risk of pancreatic cancer with higher consumption of green tea.

  • High intake may protect against cancers of the colon, esophagus and stomach.34
  • Breast cancer:
    • Reduced risk of both cancer and recurrence in epidemiological studies35
  • Colorectal cancer:
    • In a meta-analysis, high green tea consumption was associated with a moderate overall reduced risk of colorectal cancer. The reduction was significant in women (50 percent reduced risk), but not in men.36 A small pilot study of patients who had had colorectal adenomas removed showed a reduced incidence of metachronous adenomas after taking green tea extract supplements.37
    • EGCG inhibited tumor stem cell proliferation, prevented tumor production, and reduced risk of recurrence after surgery38
    • Green tea extracts prevented the development and progression of precancerous lesions, such as colorectal adenomas,39 and reduced incidence of metachronous adenomas after colorectal adenomas were removed40
  • A study from China found that women tea drinkers had significantly reduced risks of gallbladder cancer. The reduced risk was not significant in men, but a confound with smoking incidence in men could have contributed to this distinction.41
  • A 2011 review and meta-analysis found that green tea consumption was associated with a moderate reduction in risk for primary liver cancer.42
  • Reviews have found that green tea consumption shows a protective effect against lung cancer, particularly among people who had never smoked tobacco.43
  • A large cohort study found no overall association between green tea consumption and oral cancer incidence, although a trend toward reduced incidence in women was seen.44
  • Observational studies show a protective role of green tea on risk of ovarian and endometrial cancers.45 In separate reports, a case-control study in China showed a protective effect of green, black and/or oolong tea consumption against ovarian cancer,46 while a meta-analysis showed the benefits were greater with green tea for endometrial cancer..47
  • Highest green tea consumption compared to no or lowest consumption in Asian studies showed a trend toward lower risk of prostate cancer.48 Green tea catechins reduced development of prostate tumors in men with high-grade prostate intraepithelial neoplasia.49
  • Green tea polyphenols show chemopreventive properties against ultraviolet light (UVB)-induced skin cancer.50 Topical application of EGCG blocked skin cell damage from UVB.51
  • Several reviews of green tea consumption and risk of stomach cancer found a decreased risk in case control studies but not in cohort studies.52

Lab and Animal Evidence

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Optimizing Your Terrain

Creating an environment within your body that does not support cancer development, growth or spread

  • Antioxidant62
  • Anti-inflammatory63
  • Antimutagenic (counteracts the effects of mutagens, which cause genetic mutations) and anticarcinogenic64 including reduced instability in chromosomes in noncancerous colon cells65
  • Inhibited VEGF (a substance made by cells that stimulates new blood vessel formation) and other growth factors66
  • Reduced fasting blood glucose in some studies and meta-analyses,67 but not all68


Drinking green tea appears safe at regular, habitual and moderate use (three to nine cups per day).69 Side effects usually relate to gastrointestinal effects and nervous system effects from the caffeine in green tea.70

Increased tea intake was associated with an increased risk for esophageal, pancreatic, prostate, and urinary tract cancers plus leukemia in a systematic review.71

Green tea use may not be compatible with some conditions and circumstances such as pregnancy or chemotherapy treatment. In preclinical studies EGCG reduces the effect of the chemotherapy drug bortezomib (Velcade), used primarily in multiple myeloma.72 Other concerning effects in preclinical studies:73

  • Increased toxicity when used in combination with tamoxifen and irinotecan
  • Increased risk of liver toxicity if used with acetaminophen and when taken on an empty stomach
  • Elevated or interfered with liver enzymes; this effect may be reversed if consumption is stopped

Green tea consumption affects the risk of breast cancer in postmenopausal women according to the age of onset of tea drinking: green tea is protective against cancer for women who started before age 20 but increases risk for those who started after age 50.74

Green tea/EGCG also interacts with several pharmaceutical drugs and the absorption of iron.75

Further cautions and warnings regarding use of green tea/EGCG are noted.76 Please see Memorial Sloan Kettering Cancer Center’s About Herbs: Green Tea for more information and seek the advice of a trained health professional if indicated.


BCCT does not recommend therapies or doses, but only provides information for patients and providers to consider as part of a complete treatment plan. Patients should discuss therapies with their physicians, as contraindications, interactions and side effects must be evaluated. Levels of active ingredients of natural products can vary widely between and even within products. See Quality and Sources of Herbs, Supplements and Other Natural Products.

Specific dosing recommendation are available from these sources:

Integrative Programs, Protocols and Medical Systems

For more information about programs and protocols, see our Integrative Programs and Protocols page.

Abrams & Weil list green tea as effective for reducing risk and treating early stage cancer.82

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