How can green tea or EGCG help you? What the research says

Green tea and its extracts may provide substantial benefit for body terrain factors, especially body weight, high blood sugar and insulin resistance, inflammation, oxidative stress, each of which is linked to cancer development and growth.

How can green tea or EGCG help you? What the research says

We summarize the clinical evidence for each medical benefit here. We begin with our assessment of the strength of evidence within each category, followed by a brief summary of individual studies or reviews of several studies. In assessing the strength of evidence, we consider the study design, number of participants, and the size of the treatment effect (how much outcomes changed with treatment).

To see more details, click the plus sign to the right of any section.

Our assessments of evidence for each medical benefit fall into one of these categories:

Strong evidence: consistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analysesa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results
Good evidence: significant effects in one large or several mid-sized and well-designed clinical studies ( randomized controlled trialsa study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects with an appropriate placebo or other strong comparison control or observational studies that control for confounds)
Modest evidence: significant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies), or several small studies aggregated into a meta-analysis
Preliminary evidence: significant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect
Weak evidence: one or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects
Insufficient evidence: preclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example)

Learn more about how we research and rate therapies and practices in How We Rate Therapies ›

Improving treatment outcomes

Is green tea or EGCG linked to improved survival? Is it linked to less cancer growth or metastasis? Does it enhance the anticancer action of other treatments or therapies? We present the evidence.

Cancer as a whole

No evidenceoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. of major response among people with solid tumors treated with green tea extract in a small trial

Breast cancer

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of lower biomarkersa chemical or substance, such as certain proteins or genetic material, that are associated with the presence of cancer or a change in status or prognosis; these markers can be detected in blood, urine, or tissue. Tumor markers are not direct measures of clinical outcomes such as survival or metastasis, and if a therapy or treatment shows an impact only on tumor markers, we cannot surmise that it will affect survival. of cancer among people with breast cancer treated with green tea extracts or EGCG

Lower serum hepatocyte growth factor (HGF) but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on VEGF or other biomarkers after completing adjuvanttreatment applied after initial treatment for cancer, especially to suppress secondary tumor formation treatment among women with stage 1–3 breast cancer treated with Polyphenon E, a green tea extract, for 6 months compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects²Crew KD, Ho KA et al. Effects of a green tea extract, Polyphenon E, on systemic biomarkers of growth factor signalling in women with hormone receptor-negative breast cancer. Journal of Human Nutrition and Dietetics. 2015 Jun;28(3):272-82.
Lower markers of cancer [serum levels of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) and reduced activation of metalloproteinase-9 and metalloproteinase-2 (MMP9/MMP2)] and other markers of anticancer effects during radiotherapy treatment among people with locally advanced breast cancer treated with 400 mg oral EGCG capsules 3 times a day for 2 to 8 weeks compared to radiotherapy alone in a small RCT³Zhang G, Wang Y et al. Anti-cancer activities of tea epigallocatechin-3-gallate in breast cancer patients under radiotherapy. Current Molecular Medicine. 2012 Feb;12(2):163-76.
Lower Ki-67 levels, a marker of tumor proliferation, in benign cells and a weak trend toward lower levels in malignant cells among postmenopausal women with ductal carcinoma in situ (DCIS) or stage 1–2 primary breast cancer treated with 940 mg green tea capsules per day for an average of 35 days before surgery compared to no green tea in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁴Yu SS, Spicer DV et al. Biological effects of green tea capsule supplementation in pre-surgery postmenopausal breast cancer patients. Frontiers in Oncology. 2013 Dec 13;3:298.

Gynecological cancer

Preliminary evidence of higher rate of “best observed complete response” but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on histologicalrelating to the study of the structure of cells and tissue seen under a microscope response among women diagnosed with primary and recurrent usual type vulval intraepithelial neoplasia (uVIN) treated with an ointment derived from green tea

Leukemia

No evidence of an effect on survival among elderly people with acute myeloid leukemia with myelodysplasia-related changes treated with green tea extract in a small trial

No evidence of an effect on survival among elderly people with acute myeloid leukemia with myelodysplasia-related changes treated with 1000 mg green tea extracts per day compared to controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁶Calgarotto AK, Longhini AL et al. Immunomodulatory effect of green tea treatment in combination with low-dose chemotherapy in elderly acute myeloid leukemia patients with myelodysplasia-related changes. Integrative Cancer Therapies. 2021 Jan-Dec;20:15347354211002647.

Weak evidence of tumor response among people with chronic lymphocytic leukemia (CLL) treated with oral Polyphenon E

One partial remission, ⅓ of people having at least 20% lower absolute lymphocyte count, and lower total nodal areas among previously untreated people with asymptomatic Rai stage 0 to II chronic lymphocytic leukemia (CLL) treated with oral Polyphenon E with 400 to 2,000 mg EGCG twice a day in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁷Shanafelt TD, Call TG et al. Phase I trial of daily oral Polyphenon E in patients with asymptomatic Rai stage 0 to II chronic lymphocytic leukemia. Journal of Clinical Oncology. 2009 Aug 10;27(23):3808-14.
31% of people had a sustained 20% or greater reduction in ALC and 69% of people with palpable adenopathy showed a 50% or greater reduction in the sum of the products of all nodal areas among previously untreated people with asymptomatic Rai stage 0-II CLL and an absolute lymphocyte count (ALC) of 10 ×109 per liter or higher treated with 2000 mg Polyphenon E twice a day for up to 6 months in a small uncontrolled trial⁸Shanafelt TD, Call TG et al. Phase 2 trial of daily, oral Polyphenon E in patients with asymptomatic, Rai stage 0 to II chronic lymphocytic leukemia. Cancer 2013; 119:363–70.

Lung cancer

No evidence of an effect on objective tumor responses among people with lung cancer treated with green tea extract in a small trial

Melanoma and other skin cancers

No evidence of an effect on complete histological tumor clearance or tumor size among people with a primary superficial basal cell carcinoma treated with topical sinecatechins ointment in a small trial

Ovarian cancer

Preliminary evidence of lower mortality among people with epithelial ovarian cancer drinking green tea

Prostate cancer

Weak evidence of lower prostate-specific antigen (PSA) levels among men with prostate cancer treated with green tea or green tea catechins

Insufficient (conflicting) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of an effect on prostate-specific antigen (PSA) levels or other biomarkersa chemical or substance, such as certain proteins or genetic material, that are associated with the presence of cancer or a change in status or prognosis; these markers can be detected in blood, urine, or tissue. Tumor markers are not direct measures of clinical outcomes such as survival or metastasis, and if a therapy or treatment shows an impact only on tumor markers, we cannot surmise that it will affect survival. of cancer among men with prostate cancer treated with Polyphenon E, EGCG, or green tea extracts

Green tea beverage: weak evidence of lower prostate-specific antigen (PSA) levels among men with prostate cancer treated with green tea or green tea catechins

A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower prostate-specific antigen (PSA) levels among men with or at high risk of prostate cancer treated with green tea or green tea catechins compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest or water, with stronger effects with catechins compared to green tea, in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 7 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹²Sharifi-Zahabi E, Hajizadeh-Sharafabad F, Abdollahzad H, Dehnad A, Shidfar F. The effect of green tea on prostate specific antigen (PSA): a systematic review and meta-analysis of randomized controlled trials. Complementary Therapies in Medicine. 2021 Mar;57:102659.

Green tea supplements: insufficient (conflicting) evidence of an effect on prostate-specific antigen (PSA) levels or other biomarkers of cancer among men with prostate cancer treated with Polyphenon E, EGCG, or green tea extracts

A weak trend toward lower serum PSA levels and Gleason scores but no evidence of an effect on cell proliferation, apoptosis, or angiogenesis at the time of radical prostatectomy among men with prostate cancer treated with Polyphenon E containing 800 mg EGCE a day for 3 to 6 weeks compared to placebo in a small RCT¹³Nguyen MM, Ahmann FR et al. Randomized, double-blind, placebo-controlled trial of Polyphenon E in prostate cancer patients before prostatectomy: evaluation of potential chemopreventive activities. Cancer Prevention Research (Philadelphia). 2012 Feb;5(2):290-8.
Lower serum levels of prostate-specific antigen (PSA), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF), plus lower liver enzymes, among men with positive prostate biopsies scheduled for radical prostatectomy treated with Polyphenon E containing 800 mg EGCG every day until radical prostatectomy compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design¹⁴McLarty J, Bigelow RL et al. Tea polyphenols decrease serum levels of prostate-specific antigen, hepatocyte growth factor, and vascular endothelial growth factor in prostate cancer patients and inhibit production of hepatocyte growth factor and vascular endothelial growth factor in vitro. Cancer Prevention Research (Philadelphia). 2009 Jul;2(7):673-82.
No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on prostate-specific antigen (PSA) levels among people with androgen independent prostate carcinoma treated with 6 grams of oral green tea per day in 6 divided doses compared to baseline in a small uncontrolled trial¹⁵Jatoi A, Ellison N et al. A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma. Cancer. 2003 Mar 15;97(6):1442-6.
No evidence of an effect on Ki-67 levels in prostate tissue after repeat prostate biopsy following an initial negative prostate biopsy among men treated with EGCG, whether with or without fish oil, compared to placebo in a small RCT¹⁶Zhang Z, Garzotto M et al. Effects of ω-3 fatty acids and catechins on fatty acid synthase in the prostate: a randomized controlled trial. Nutrition and Cancer. 2016 Nov-Dec;68(8):1309-1319.

Green tea or EGCG combined with other therapies

Preliminary evidence of lower disease progression rate after treatment with leucovorin, 5-fluorouracil, and oxaliplatin among people with metastatic colorectal cancer treated with MB-6

Optimizing your body terrain

Does green tea or EGCG promote an environment within your body that is less supportive of cancer development, growth, or spread? We present the evidence.

See Optimizing Your Body Terrain ›

Find medical professionals who specialize in managing body terrain factors: Finding Integrative Oncologists and Other Practitioners ›

Bleeding and coagulation imbalance

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on coagulation indicators among healthy non-smoking females eating a diet rich in linoleic acid and treated with green tea extract in a small trial (not specific to cancer)

Body weight

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of lower weight, waist circumference, and body fat among people drinking green tea or beverages containing green tea catechins (not specific to cancer)

Green tea beverage: good evidence of lower weight, waist circumference, and body fat among people drinking green tea or beverages containing green tea catechins (not specific to cancer)

Lower weight and waist circumference among people drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 13 meta-analyses¹⁹Neyestani TR, Nikooyeh B. A comprehensive overview on the effects of green tea on anthropometric measures, blood pressure, glycemic and lipidemic status: An umbrella review and meta meta-analysis study. Nutrition, Metabolism, and Cardiovascular Diseases. 2022 Sep;32(9):2026-2040.
Lower total fat area, visceral fat area, subcutaneous fat area, body weight, body mass index, and waist circumference among people drinking beverages with green tea catechins for 12 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a meta-analysis of 6 controlled trialsa study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial²⁰Hibi M, Takase H, Iwasaki M, Osaki N, Katsuragi Y. Efficacy of tea catechin-rich beverages to reduce abdominal adiposity and metabolic syndrome risks in obese and overweight subjects: a pooled analysis of 6 human trials. Nutrition Research. 2018 Jul;55:1-10.
Lower body weight among women with PCOS treated with green tea supplements compared to placebo in a meta-analysis of 4 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects, although no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on body mass index, waist circumference, hip circumference, waist-to-hip ratio, or body fat rate in meta-analyses of 2 to 4 RCTs²¹Shen W, Pan Y et al. Effects of tea consumption on anthropometric parameters, metabolic indexes and hormone levels of women with polycystic ovarian syndrome: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Endocrinology (Lausanne). 2021 Dec 13;12:736867.
Slightly lower fat mass overall and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently among Asian people only on body weight, or waist or hip circumference, although no evidence of an effect among other people drinking green tea compared to controls in a meta-analysis of 5 RCTs²²Baladia E, Basulto J, Manera M, Martínez R, Calbet D. Efecto del consumo de té verde o extractos de té verde en el peso y en la composición corporal; revisión sistemática y metaanálisis [Effect of green tea or green tea extract consumption on body weight and body composition; systematic review and meta-analysis]. Nutrición Hospitalaria. 2014 Mar 1;29(3):479-90. Spanish.
Lower body weight and body mass index among people with obesity and metabolic syndromea cluster of conditions that occur together, including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels drinking 4 cups of green tea or treated with green tea extracts with equivalent EGCG content and liquid for 8 weeks compared to water in a small RCT²³Basu A, Sanchez K et al. Green tea supplementation affects body weight, lipids, and lipid peroxidation in obese subjects with metabolic syndrome. Journal of the American College of Nutrition. 2010 Feb;29(1):31-40.

Green tea supplements or herbals containing green tea: insufficient (conflicting) evidence of an effect on body weight or weight loss among people treated with green tea extracts in several combined studies (not specific to cancer)

No evidence of an effect on weight loss (8 studies), body mass index (5 studies), or waist circumference (5 studies) among people outside Japan treated with green tea preparations for at least 12 weeks compared to controls in meta-analyses of RCTs²⁴Jurgens TM, Whelan AM et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database of Systematic Reviews. 2012 Dec 12;12(12):CD008650.
Lower body weight and maintenance of weight loss among people treated with green tea catechins compared to controls in a meta-analysis of 11 clinical trials²⁵Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity (Lond). 2009 Sep;33(9):956-61.
Lower body weight among women with polycystic ovary syndrome (PCOS) supplemented with green tea compared to placebo in a meta-analysis of 4 RCTs of very low quality²⁶Colonetti L, Grande AJ et al. Green tea promotes weight loss in women with polycystic ovary syndrome: systematic review and meta-analysis. Nutrition Research. 2022 Aug;104:1-9.
No evidence of an effect among people treated with green tea extracts compared to controls in a meta-analysis of 5 RCTs²⁷Baladia E, Basulto J, Manera M, Martínez R, Calbet D. Efecto del consumo de té verde o extractos de té verde en el peso y en la composición corporal; revisión sistemática y metaanálisis [Effect of green tea or green tea extract consumption on body weight and body composition; systematic review and meta-analysis]. Nutrición Hospitalaria. 2014 Mar 1;29(3):479-90. Spanish.
Lower weight, body mass index, waist circumference, and hip circumference among overweight or obese adults treated with herbals containing green tea compared to controls in a meta-analysis of 15 RCTs and observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies²⁸Payab M, Hasani-Ranjbar S et al. Effect of the herbal medicines in obesity and metabolic syndrome: a systematic review and meta-analysis of clinical trials. Phytotherapy Research. 2020 Mar;34(3):526-545.
Lower body mass index and waist circumference among obese people treated with green tea extract compared to placebo in a small RCT²⁹Suliburska J, Bogdanski P et al. Effects of green tea supplementation on elements, total antioxidants, lipids, and glucose values in the serum of obese patients. Biological Trace Element Research. 2012 Dec;149(3):315-22.

High blood sugar and insulin resistance

Good evidence of lower fasting blood sugar (glucose), but no evidence of an effect among people drinking decaffeinated green tea or on other glycemic indicators among people drinking green tea (not specific to cancer)

Insufficient (conflicting) evidence of an effect on fasting insulin or markers of blood sugar among people treated with green tea extract or EGCG (not specific to cancer)

Green tea beverage: good evidence of lower fasting blood sugar (glucose), but no evidence of an effect among people drinking decaffeinated green tea or on other glycemic indicators among people drinking green tea (not specific to cancer)

Lower fasting blood sugar (glucose) but no evidence of an effect on other glycemic indicators among people drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 13 meta-analyses³⁰Neyestani TR, Nikooyeh B. A comprehensive overview on the effects of green tea on anthropometric measures, blood pressure, glycemic and lipidemic status: an umbrella review and meta meta-analysis study. Nutrition, Metabolism, and Cardiovascular Diseases. 2022 Sep;32(9):2026-2040.
Lower fasting blood sugar (glucose) levels among people drinking green tea (11 studies), but not decaffeinated green tea (6 studies) compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest or water in meta-analyses of observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies³¹Kondo Y, Goto A et al. Effects of coffee and tea consumption on glucose metabolism: a systematic review and network meta-analysis. Nutrients. 2018 Dec 27;11(1):48.

Green tea supplements, EGCG, or combined beverage and supplements: insufficient (conflicting) evidence of an effect on fasting insulin or markers of blood sugar among people treated with green tea extract or EGCG (not specific to cancer)

Substantially lower fasting insulin among women with PCOS treated with green tea supplements compared to placebo in a meta-analysis of 2 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects³²Shen W, Pan Y et al. Effects of tea consumption on anthropometric parameters, metabolic indexes and hormone levels of women with polycystic ovarian syndrome: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Endocrinology (Lausanne). 2021 Dec 13;12:736867.
No evidence of an effect on in markers of blood sugar, fasting insulin, or fasting glucose among people with prediabetes or type 2 diabetes drinking green tea or treated with green tea extract compared to placebo in a meta-analysis of 6 RCTs³³Yu J, Song P, Perry R, Penfold C, Cooper AR. The effectiveness of green tea or green tea extract on insulin resistance and glycemic control in type 2 diabetes mellitus: a meta-analysis. Diabetes & Metabolism Journal. 2017 Aug;41(4):251-262.
Lower plasma glucose among obese postmenopausal women with impaired glucose tolerance and exercising at moderate intensity treated with 150 mg EGCG daily for 12 weeks compared to placebo in a small RCT³⁴Hill AM, Coates AM et al. Can EGCG reduce abdominal fat in obese subjects? Journal of the American College of Nutrition. 2007 Aug;26(4):396S-402S.

Hormone imbalance

Changes in hormone levels seen in the studies here may not be beneficial in every situation. Your oncology team needs to determine whether any changes would be favorable for your condition.

Preliminary evidence of changes in gastrointestinal hormones that affect digestion and insulin secretion after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea

No evidence of an effect on growth hormones among people drinking green tea or treated with green tea extracts in several studies (not specific to cancer)

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of an effect on adiponectina hormone and signaling protein involved in regulating glucose levels and fatty acid breakdown concentrations among people with type 2 diabetes supplemented with green tea (not specific to cancer)

No evidence of an effect on adiponectin concentrations among people drinking green tea or treated with green tea extract (not specific to diabetes)

Preliminary (conflicting) evidence of higher blood total estradiol and bioavailable estradiol among healthy postmenopausal women treated with EGCG (not specific to cancer or diabetes)

Insufficient (conflicting) evidence of an effect on sex hormone levels among obese women with polycystic ovary syndrome (PCOS) treated with green tea supplements (not specific to cancer or diabetes)

No evidence of an effect on serotonin after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea in a small study

Appetite hormones

Preliminary evidence of lower levels of ghrelin—the “hunger hormone”—among obese women treated with green tea extract (not specific to cancer)

Lower levels of ghrelin among obese women not using any other weight-control measures treated with green tea extract 3 times a day for 12 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects³⁵Hsu CH, Tsai TH et al. Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial. Clinical Nutrition. 2008 Jun;27(3):363-70.

Gastrointestinal hormones

Changes in gastrointestinal hormones on day 3 and day 5 after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea compared to potable water in a small RCT:³⁶Liu D, Jing X et al. Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial. European Journal of Clinical Nutrition. 2021 Nov;75(11):1568-1577.
- Lower gastric inhibitory peptide, which promotes insulin secretion and inhibits gastric acid
- Higher levels of GLP-1, which promotes insulin secretion
- Lower levels of somatostatin, which inhibits insulin and glucagon secretion
- Higher levels of motilin, which stimulates gastric and small intestine motility, causing undigested food in these regions to move into the large intestine
- No evidence of an effect on gastrin, which promotes gastric motility and acid secretion

Growth hormones

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on growth hormones among people drinking green tea or treated with green tea extracts in several studies (not specific to cancer)

No evidence of an effect on growth hormones (IGF-1 and IGF binding protein-3) among healthy postmenopausal women treated with decaffeinated capsules containing 1315 mg total catechins including 843 mg EGCG daily for 1 year compared to placebo in a large RCT³⁷Samavat H, Wu AH et al. Green tea catechin extract supplementation does not influence circulating sex hormones and insulin-like growth factor axis proteins in a randomized controlled trial of postmenopausal women at high risk of breast cancer. Journal of Nutrition. 2019 Apr 1;149(4):619-627.
No evidence of an effect on growth hormones (IGF-1, IGF-2, IGF binding protein (BP)-2 and IGFBP-3) among men with prostate specific antigen (PSA) between 2.0 and 2.95 ng/ml drinking green tea or treated with EGCG compared to placebo in a mid-sized RCT³⁸Biernacka KM, Holly JMP et al. Effect of green tea and lycopene on the insulin-like growth factor system: the ProDiet randomized controlled trial. European Journal of Cancer Prevention. 2019 Nov;28(6):569-575.
No evidence of an effect on IGF-1 at the time of radical prostatectomy among men with prostate cancer treated with Polyphenon E containing 800 mg EGCE a day for 3 to 6 weeks compared to placebo in a small RCT³⁹Nguyen MM, Ahmann FR et al. Randomized, double-blind, placebo-controlled trial of Polyphenon E in prostate cancer patients before prostatectomy: evaluation of potential chemopreventive activities. Cancer Prevention Research (Philadelphia). 2012 Feb;5(2):290-8.

Metabolism hormones

Modest evidence of an effect on adiponectin concentrations among people with type 2 diabetes supplemented with green tea (not specific to diabetes)

No evidence of an effect on adiponectin concentrations among people drinking green tea or treated with green tea extract (not specific to diabetes)

Higher adiponectin concentrations among people with type 2 diabetes supplemented with green tea compared to controls in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 5 RCTs⁴⁰Asbaghi O, Fouladvand F et al. Effects of green tea supplementation on serum concentrations of adiponectin in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Archives of Physiology and Biochemistry. 2023 Apr;129(2):536-543.
No evidence of an effect on adiponectin concentrations among people drinking green tea or treated with green tea extract compared to placebo in a meta-analysis of 14 RCTs⁴¹Haghighatdoost F, Nobakht M Gh BF, Hariri M. Effect of green tea on plasma adiponectin levels: a systematic review and meta-analysis of randomized controlled clinical trials. Journal of the American College of Nutrition. 2017 Sep-Oct;36(7):541-548.

Sex hormones

Preliminary (conflicting) evidence of higher blood total estradiol and bioavailable estradiol among healthy postmenopausal women treated with EGCG (not specific to cancer or diabetes)

Higher blood total estradiol and bioavailable estradiol among healthy postmenopausal women treated with decaffeinated capsules containing 1315 mg total catechins including 843 mg EGCG daily for 1 year compared to placebo in a large RCT⁴²Samavat H, Wu AH et al. Green tea catechin extract supplementation does not influence circulating sex hormones and insulin-like growth factor axis proteins in a randomized controlled trial of postmenopausal women at high risk of breast cancer. Journal of Nutrition. 2019 Apr 1;149(4):619-627.
No evidence of an effect on estradiol (E2), estrone, testosterone (T), androstenedione, T/E2, or sex hormone-binding globulin among postmenopausal women treated with Polyphenon E with 400 mg EGCG or 800 mg EGCG compared to placebo in a mid-sized RCT⁴³Wu AH, Spicer D et al. Effect of 2-month controlled green tea intervention on lipoprotein cholesterol, glucose, and hormone levels in healthy postmenopausal women. Cancer Prevention Research (Philadelphia). 2012 Mar;5(3):393-402.

Insufficient (conflicting) evidence of an effect on sex hormone levels among obese women with polycystic ovary syndrome (PCOS) treated with green tea supplements (not specific to cancer or diabetes)

Lower levels of free testosterone among overweight or obese women with polycystic ovary syndrome (PCOS) treated with green tea tablets compared to placebo in a small RCT⁴⁴Tehrani HG, Allahdadian M, Zarre F, Ranjbar H, Allahdadian F. Effect of green tea on metabolic and hormonal aspect of polycystic ovarian syndrome in overweight and obese women suffering from polycystic ovarian syndrome: a clinical trial. Journal of Education and Health Promotion. 2017 May 5;6:36.
No evidence of an effect on sex hormone levels (total testosterone, DHEAS, luteinizing hormone, or follicular-stimulating hormone) among obese women with PCOS treated with green tea capsules for 3 months compared to placebo in a small RCT⁴⁵Chan CC, Koo MW et al. Effects of Chinese green tea on weight, and hormonal and biochemical profiles in obese patients with polycystic ovary syndrome–a randomized placebo-controlled trial. Journal of the Society for Gynecologic Investigation. 2006 Jan;13(1):63-8.

Other hormones

No evidence of an effect on serotonin after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea in a small study

No evidence of an effect on serotonin after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea compared to potable water in a small RCT⁴⁶Liu D, Jing X et al. Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial. European Journal of Clinical Nutrition. 2021 Nov;75(11):1568-1577.

Immune function

Increased immune system activation is not always beneficial, so your oncology team needs to determine whether immune activation would be favorable in your situation.

No evidence of an effect on markers of immune activation after robotic or laparoscopic subtotal gastrectomy among people with stomach cancer drinking green tea

Preliminary evidence of immune activation among elderly people with acute myeloid leukemia with myelodysplasia-related changes treated with green tea extracts

Preliminary evidence of immune activation among healthy adults treated with green tea capsules (not specific to cancer)

Green tea beverage: no evidence of an effect on markers of immune activation after robotic or laparoscopic subtotal gastrectomy among people with stomach cancer drinking green tea

No evidence of an effect on markers of immune activation (leucocyte count or percentage of neutrophils) after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea compared to potable water in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁴⁷Liu D, Jing X et al. Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial. European Journal of Clinical Nutrition. 2021 Nov;75(11):1568-1577.

Green tea extracts

Preliminary evidence of immune activation among elderly people with acute myeloid leukemia with myelodysplasia-related changes treated with green tea extracts

Immune responses including better cytotoxic response and higher markers of immune activation among elderly people with acute myeloid leukemia with myelodysplasia-related changes treated with 1000 mg green tea extracts per day for at least 6 months or until progression compared to controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁴⁸Calgarotto AK, Longhini AL et al. Immunomodulatory effect of green tea treatment in combination with low-dose chemotherapy in elderly acute myeloid leukemia patients with myelodysplasia-related changes. Integrative Cancer Therapies. 2021 Jan-Dec;20:15347354211002647.

Preliminary evidence of immune activation among healthy adults treated with green tea capsules (not specific to cancer)

A higher marker of immune activation (proliferation of gammadelta T cells), fewer symptoms of cold and flu, and a weak trend toward fewer incidence of cold or flu of at least 2 days among healthy adults treated with green tea capsules for 12 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a mid-sized RCT⁴⁹Rowe CA, Nantz MP, Bukowski JF, Percival SS. Specific formulation of Camellia sinensis prevents cold and flu symptoms and enhances gamma,delta T cell function: a randomized, double-blind, placebo-controlled study. Journal of the American College of Nutrition. 2007 Oct;26(5):445-52.

Inflammation

Preliminary evidence of some lower markers of inflammation among people with prostate or stomach cancer drinking green tea

Modest evidence of a lower marker of inflammation among people with type 2 diabetes drinking green tea (not specific to cancer)

No evidence of an effect on a lower marker of inflammation among people who had undergone complete removal of colorectal adenomas treated with green tea extract in one study

Preliminary evidence of lower infiltration of inflammatory leukocytes after a single dose of ultraviolet radiation among people treated with EGCG (not specific to cancer or diabetes)

Green tea beverage

Preliminary evidence of some lower markers of inflammation among people with prostate or stomach cancer drinking green tea

A lower marker of inflammation (NFκB) among men with prostate cancer drinking 6 cups of green tea a day compared to water in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁵⁰Henning SM, Wang P et al. Randomized clinical trial of brewed green and black tea in men with prostate cancer prior to prostatectomy. Prostate. 2015 Apr 1;75(5):550-9.
Some lower markers of inflammation (TNF-α and procalcitonin) but no evidence of an effect on C-reactive protein (CRP) or interleukin-6 (IL-6) after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea compared to potable water in a small RCT⁵¹Liu D, Jing X et al. Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial. European Journal of Clinical Nutrition. 2021 Nov;75(11):1568-1577.

Modest evidence of a lower marker of inflammation among people with type 2 diabetes drinking green tea (not specific to cancer)

A lower marker of inflammation (C-reactive protein) among people with type 2 diabetes drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 8 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁵²Asbaghi O, Fouladvand F et al. The effect of green tea on C-reactive protein and biomarkers of oxidative stress in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Complementary Therapies in Medicine. 2019 Oct;46:210-216.

Green tea extracts

No evidence of an effect on a lower marker of inflammation among people who had undergone complete removal of colorectal adenomas treated with green tea extract in one study

No evidence of an effect on a lower marker of inflammation (C-reactive protein) among people who had undergone complete removal of colorectal adenomas by endoscopic polypectomy treated with 0.9 g green tea extract per day for 12 months compared to no supplementation in a mid-sized RCT⁵³Shin CM, Lee DH et al. Green tea extracts for the prevention of metachronous colorectal polyps among patients who underwent endoscopic removal of colorectal adenomas: a randomized clinical trial. Clinical Nutrition. 2018 Apr;37(2):452-458.

Weak evidence of one lower marker of inflammation but not another among people treated with green tea capsules (not specific to diabetes)

One lower marker of inflammation (NF-κB mRNA) but no evidence of an effect on another (C-reactive protein) among people treated with green tea capsules containing 800 mg EGCG compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁵⁴Hu Y, McIntosh GH et al. Supplementation with Brazil nuts and green tea extract regulates targeted biomarkers related to colorectal cancer risk in humans. British Journal of Nutrition. 2016 Dec;116(11):1901-1911.

Topical EGCG

Preliminary evidence of lower infiltration of inflammatory leukocytes after a single dose of ultraviolet radiation among people treated with EGCG (not specific to cancer or diabetes)

Lower infiltration of inflammatory leukocytes after a single 4x minimal erythema dose of ultraviolet radiation among people treated with EGCG (mg/cm2 skin) compared to controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁵⁵Katiyar SK, Afaq F, Perez A, Mukhtar H. Green tea polyphenol (-)-epigallocatechin-3-gallate treatment of human skin inhibits ultraviolet radiation-induced oxidative stress. Carcinogenesis. 2001 Feb;22(2):287-94.

Oxidative stress

Preliminary evidence of a lower marker of systemic oxidative DNA damage but no evidence of an effect on oxidative DNA damage in prostatectomy tissue among men with prostate cancer drinking green tea

Modest evidence of lower markers of oxidative stressan imbalance between free radicals and antioxidants in your body in which antioxidant levels are lower than normal; this imbalance can cause harmful oxidation reactions in your body chemistry among smokers drinking green tea (not specific to cancer)

No evidence of an effect on measures of oxidative stress among people with type 2 diabetes drinking green tea in a combined analysis of studies (not specific to cancer)

Preliminary evidence of lower markers of oxidative stress among people with obesity and metabolic syndromea cluster of conditions that occur together, including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels drinking green tea (not specific to cancer)

Weak evidence of a lower marker of oxidative stress at the time of radical prostatectomy among men with prostate cancer treated with Polyphenon E

Weak evidence of lower levels of one marker of oxidative stress but not another among people with inoperable hepatocellular carcinoma (HCC) or metastatic liver cancers from colorectal malignancy treated with green tea polyphenol tablets

Preliminary evidence of a lower marker of oxidative DNA damage among people sero-positive for both HBsAg and aflatoxin-albumin adducts—risk factors for cancer—treated with green tea polyphenols

Preliminary evidence of a lower marker of oxidative stress among obese people treated with green tea extract (not specific to cancer)

Preliminary evidence of a lower marker of oxidative stress, especially among smokers, among people treated with green tea extract incorporated into meat patties (not specific to cancer)

Preliminary evidence of one lower marker of oxidative stress but not others among healthy non-smoking females treated with green tea extract (not specific to cancer)

Preliminary evidence of lower markers of oxidative stress after exposure to ultraviolet (UV) radiation among people treated with topical application of EGCG (not specific to cancer)

Green tea beverage

Preliminary evidence of a lower marker of systemic oxidative DNA damage but no evidence of an effect on oxidative DNA damage in prostatectomy tissue among men with prostate cancer drinking green tea

A lower marker of systemic oxidative DNA damage (8OHdG) but no evidence of an effect on oxidative DNA damage in prostatectomy tissue from men with prostate cancer drinking 6 cups of green tea a day compared to water in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁵⁶Henning SM, Wang P et al. Randomized clinical trial of brewed green and black tea in men with prostate cancer prior to prostatectomy. Prostate. 2015 Apr 1;75(5):550-9.

Modest evidence of lower markers of oxidative stress among smokers drinking green tea (not specific to cancer)

A lower marker of oxidative stress (urinary 8-OHdG) among heavy smokers drinking 4 cups (960 mL) of decaffeinated green tea per day for 4 months, but not among those drinking black tea, compared to water in 3 mid-sized RCTs;⁵⁷Hakim IA, Chow HH, Harris RB. Green tea consumption is associated with decreased DNA damage among GSTM1-positive smokers regardless of their hOGG1 genotype. Journal of Nutrition. 2008 Aug;138(8):1567S-1571S; Hakim IA, Harris RB et al. Effect of increased tea consumption on oxidative DNA damage among smokers: a randomized controlled study. Journal of Nutrition. 2003 Oct;133(10):3303S-3309S; Hakim IA, Harris RB et al. Effect of a 4-month tea intervention on oxidative DNA damage among heavy smokers: role of glutathione S-transferase genotypes. Cancer Epidemiology, Biomarkers & Prevention. 2004 Feb;13(2):242-9. one study showed the greatest reductions among people with GSTM1 positive genotypes,⁵⁸Hakim IA, Chow HH, Harris RB. Green tea consumption is associated with decreased DNA damage among GSTM1-positive smokers regardless of their hOGG1 genotype. Journal of Nutrition. 2008 Aug;138(8):1567S-1571S. and another study showed reductions among both GSTM1-positive and GSTT1-positive people, a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward reduction in GSTM1-negative people, but no evidence of an effect among GSTT1-negative people⁵⁹Hakim IA, Harris RB et al. Effect of a 4-month tea intervention on oxidative DNA damage among heavy smokers: role of glutathione S-transferase genotypes. Cancer Epidemiology, Biomarkers & Prevention. 2004 Feb;13(2):242-9.
A lower marker of oxidative stress (urinary 8-OHdG) among smokers regardless of their hOGG1 genotype drinking 4 cups (960 mL) of decaffeinated green tea per day for 4 months compared to water, with stronger effects among GSTM1-positive people, in a mid-sized RCT⁶⁰Hakim IA, Chow HH, Harris RB. Green tea consumption is associated with decreased DNA damage among GSTM1-positive smokers regardless of their hOGG1 genotype. Journal of Nutrition. 2008 Aug;138(8):1567S-1571S.
Lower levels of smoke-induced mutations, comparable to levels in nonsmokers, among healthy male smokers drinking 3 cups of green tea per day for 6 months compared to no green tea in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial⁶¹Lee IP, Kim YH et al. Chemopreventive effect of green tea (Camellia sinensis) against cigarette smoke-induced mutations (SCE) in humans. Journal of Cellular Biochemistry. Supplement. 1997;27:68-75.

No evidence of an effect on measures of oxidative stress among people with type 2 diabetes drinking green tea in a combined analysis of studies (not specific to cancer)

No evidence of an effect on measures of oxidative stress (malondealdehyde and total antioxidant capacity) among people with type 2 diabetes drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 8 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies⁶²Asbaghi O, Fouladvand F et al. The effect of green tea on C-reactive protein and biomarkers of oxidative stress in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Complementary Therapies in Medicine. 2019 Oct;46:210-216.

Either green tea beverage or supplements: preliminary evidence of lower markers of oxidative stress among people with obesity and metabolic syndrome drinking green tea (not specific to cancer)

Lower markers of oxidative stress (malondialdehyde and hydroxynonenals) among people with obesity and metabolic syndrome drinking 4 cups of green tea or treated with green tea extracts with equivalent EGCG content and liquid for 8 weeks compared to water in a small RCT⁶³Basu A, Sanchez K et al. Green tea supplementation affects body weight, lipids, and lipid peroxidation in obese subjects with metabolic syndrome. Journal of the American College of Nutrition. 2010 Feb;29(1):31-40.
Higher plasma antioxidant capacity and higher levels of an antioxidant (glutathione) among obese people with the metabolic syndrome either drinking 4 cups of green tea per day or taking 2 capsules green tea extract and 4 cups water per day for 8 weeks compared to water in a small RCT⁶⁴Basu A, Betts NM et al. Green tea supplementation increases glutathione and plasma antioxidant capacity in adults with the metabolic syndrome. Nutrition Research. 2013 Mar;33(3):180-7.

Green tea supplements

Weak evidence of a lower marker of oxidative stress at the time of radical prostatectomy among men with prostate cancer treated with Polyphenon E

A weak trend toward a lower marker of oxidative stress (8OHdG) at the time of radical prostatectomy among men with prostate cancer treated with Polyphenon E containing 800 mg EGCE a day for 3 to 6 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCT⁶⁵Nguyen MM, Ahmann FR et al. Randomized, double-blind, placebo-controlled trial of Polyphenon E in prostate cancer patients before prostatectomy: evaluation of potential chemopreventive activities. Cancer Prevention Research (Philadelphia). 2012 Feb;5(2):290-8.

Lower levels of derivatives of reactive oxygen metabolites but no evidence of an effect on biological antioxidative potential among people with inoperable hepatocellular carcinoma (HCC) or metastatic liver cancers from colorectal malignancy treated with 6 oral green tea polyphenol tablets per day, with each tablet having 79 mg EGCG, for 6 to 9 months compared to baseline, but no evidence of an effect from 3 tablets in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁶⁶Baba Y, Sonoda JI et al. Reduction of oxidative stress in liver cancer patients by oral green tea polyphenol tablets during hepatic arterial infusion chemotherapy. Experimental and Therapeutic Medicine. 2012 Sep;4(3):452-458.

Preliminary evidence of a lower marker of oxidative DNA damage among people sero-positive for both HBsAg and aflatoxin-albumin adducts—risk factors for cancer—treated with green tea polyphenols

A lower marker of oxidative DNA damage (8-OHdG levels) among people sero-positive for both HBsAg and aflatoxin-albumin adducts treated with 500 mg or 1000 mg green tea polyphenols a day for 3 months compared to placebo in a mid-sized RCT⁶⁷Luo H, Tang L et al. Phase IIa chemoprevention trial of green tea polyphenols in high-risk individuals of liver cancer: modulation of urinary excretion of green tea polyphenols and 8-hydroxydeoxyguanosine. Carcinogenesis. 2006 Feb;27(2):262-8.

Preliminary evidence of a lower marker of oxidative stress among obese people treated with green tea extract (not specific to cancer)

Higher total antioxidant status among obese people treated with green tea extract compared to placebo in a small RCT⁶⁸Suliburska J, Bogdanski P et al. Effects of green tea supplementation on elements, total antioxidants, lipids, and glucose values in the serum of obese patients. Biological Trace Element Research. 2012 Dec;149(3):315-22.

Preliminary evidence of a lower marker of oxidative stress, especially among smokers, among people treated with green tea extract incorporated into meat patties (not specific to cancer)

Higher plasma antioxidant capacity, especially among smokers, among people treated with green tea extract incorporated into meat patties corresponding to a daily intake of 18.6 mg catechins per day, with a half-life of less than 2 hours and no effect on fasting levels of oxidation compared to controls in a small RCT⁶⁹Young JF, Dragstedt LO et al. Green tea extract only affects markers of oxidative status postprandially: lasting antioxidant effect of flavonoid-free diet. British Journal of Nutrition. 2002 Apr;87(4):343-55.

Preliminary evidence of one lower marker of oxidative stress but not others among healthy non-smoking females treated with green tea extract (not specific to cancer)

Lower levels of plasma malondialdehyde but no evidence of an effect on other markers of oxidative stress among healthy non-smoking females eating a diet rich in linoleic acid and treated with 3 g green tea extract per day for 4 weeks compared to placebo in a small controlled trial⁷⁰Freese R, Basu S et al. Green tea extract decreases plasma malondialdehyde concentration but does not affect other indicators of oxidative stress, nitric oxide production, or hemostatic factors during a high-linoleic acid diet in healthy females. European Journal of Nutrition. 1999 Jun;38(3):149-57.

Topical green tea or EGCG: preliminary evidence of lower markers of oxidative stress after exposure to ultraviolet (UV) radiation among people treated with topical application of EGCG (not specific to cancer)

Lower markers of oxidative stress (infiltration of leukocytes and myeloperoxidase activity) after exposure to UVB radiation among people treated with topical application of 3 mg EGCG/2.5 cm2 before UVB exposure compared to controls in a small RCT⁷¹Katiyar SK, Matsui MS, Elmets CA, Mukhtar H. Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin. Photochemistry and Photobiology. 1999 Feb;69(2):148-53.
Less solar radiation-induced oxidative damage to DNA and Langerhans cells among healthy people or skin explants treated with green tea after UV irradiation compared to controls in a small RCT⁷²Camouse MM, Domingo DS et al. Topical application of green and white tea extracts provides protection from solar-simulated ultraviolet light in human skin. Experimental Dermatology. 2009 Jun;18(6):522-6.
Lower UV-induced markers of oxidative stress (hydrogen peroxide and nitric oxide) and restored levels of glutathione after a single 4x minimal erythema dose of ultraviolet radiation among people treated with topical EGCG (mg/cm2 skin) compared to controls in a small controlled trial⁷³Katiyar SK, Afaq F, Perez A, Mukhtar H. Green tea polyphenol (-)-epigallocatechin-3-gallate treatment of human skin inhibits ultraviolet radiation-induced oxidative stress. Carcinogenesis. 2001 Feb;22(2):287-94.

Your microbiome

No evidence of an effect on bacterial diversity and community structures among adults treated with green tea capsules in a small study

Other terrain factors

Good evidence of lower ratio of polyunsaturated fatty acids relative to total fatty acids among men with raised PSAprostate-specific antigen: a protein produced by both normal and malignant cells of the prostate gland; the blood level of PSA is often elevated in men with prostate cancer levels advised to drink green tea

Green tea combined with other therapies

Preliminary evidence of lower body weight, smaller waist circumference, lower fasting insulin levels, fasting glucose levels, and a higher marker of antioxidant activity among elderly men and women participating in moderately intense walking, drinking green tea, and treated with vitamin E (not specific to cancer)

Preliminary evidence of lower markers of oxidative stress among healthy people treated with green tea polyphenol infused with milk (not specific to cancer)

Weak evidence of lower markers of oxidative stress among healthy people drinking a liquid contained mangosteen, aloe vera, green tea, and multivitamins (not specific to cancer)

No evidence of an effect on prostate-specific antigen doubling time among men with biochemical recurrence with a moderate PSA rise rate treated with a phytotherapeutic intervention containing turmeric, resveratrol, green tea, and broccoli sprouts in a small study

Green tea, vitamin E, and walking: preliminary evidence of lower body weight, smaller waist circumference, lower fasting insulin levels, fasting glucose levels, and a higher marker of antioxidant activity among elderly men and women participating in moderately intense walking, drinking green tea, and treated with vitamin E (not specific to cancer)

Lower body weight, smaller waist circumference, lower fasting insulin levels, fasting glucose levels, and a higher marker of antioxidant activity (erythrocyte catalase activities) among elderly men and women participating in moderately intense walking 6 days a week, drinking 3 cups of green tea and treated with 400 IU vitamin E for 12 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁷⁶Narotzki B, Reznick AZ, Navot-Mintzer D, Dagan B, Levy Y. Green tea and vitamin E enhance exercise-induced benefits in body composition, glucose homeostasis, and antioxidant status in elderly men and women. Journal of the American College of Nutrition. 2013;32(1):31-40.

Green tea polyphenol with milk: preliminary evidence of lower markers of oxidative stress among healthy people treated with green tea polyphenol infused with milk (not specific to cancer)

Higher antioxidant index and antioxidant enzyme activities and lower levels of lipid peroxidation among healthy people treated with green tea polyphenol infused with milk for 6 months compared to placebo in a small RCT⁷⁷Chiu HF, Lin TY, Shen YC, Venkatakrishnan K, Wang CK. Improvement of green tea polyphenol with milk on skin with respect to antioxidation in healthy adults: a double-blind placebo-controlled randomized crossover clinical trial. Food & Function. 2016 Feb;7(2):893-901.

Mangosteen, aloe vera, green tea, and multivitamins: weak evidence of lower markers of oxidative stress among healthy people drinking a liquid contained mangosteen, aloe vera, green tea, and multivitamins (not specific to cancer)

Higher antioxidant capacity (oxygen radical absorbance capacity) among healthy people drinking a liquid contained mangosteen, aloe vera, green tea, and multivitamins compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁷⁸Kondo M, Zhang L, Ji H, Kou Y, Ou B. Bioavailability and antioxidant effects of a xanthone-rich Mangosteen (Garcinia mangostana) product in humans. Journal of Agricultural and Food Chemistry. 2009 Oct 14;57(19):8788-92.

Supplements containing turmeric, resveratrol, green tea, and broccoli sprouts: no evidence of an effect on prostate-specific antigen doubling time among men with biochemical recurrence with a moderate PSA rise rate treated with a phytotherapeutic intervention containing turmeric, resveratrol, green tea, and broccoli sprouts in a small study

No evidence of an effect on prostate-specific antigen (PSA) doubling time among men with biochemical recurrence with a moderate PSA rise rate treated with a phytotherapeutic intervention containing turmeric, resveratrol, green tea, and broccoli sprouts for 12 weeks compared to placebo in a small RCT⁷⁹van Die MD, Williams SG et al. A placebo-controlled double-blinded randomized pilot study of combination phytotherapy in biochemically recurrent prostate cancer. Prostate. 2017 May;77(7):765-775.

Also see separate reviews of products containing green tea extracts:

Pomi-T, a blend of pomegranate extracts, green tea extracts, turmeric, and broccoli extracts: Pomi-T ›
Zyflamend, a blend of rosemary, turmeric, ginger, holy basil, green tea, hu zhang, Chinese goldthread, barberry, oregano, and baikal skullcap: Zyflamend ›

Managing side effects and promoting wellness

Is green tea or EGCG linked to fewer or less severe side effects or symptoms? Is it linked to less toxicity from cancer treatment? Does it support your quality of life or promote general well-being? We present the evidence.

Fatigue

Gastrointestinal symptoms

Preliminary evidence of shorter time to gastrointestinal function recovery after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea

Preliminary evidence of lower incidence and less severe diarrhea after radiotherapy among people with abdomen and pelvic malignancy treated with green tea tablets

Preliminary evidence of less esophagitis during or after chemoradiotherapy among people with lung cancer treated with EGCG before or during chemoradiotherapy

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on vomiting after radiotherapy among people with abdomen and pelvic malignancy treated with green tea tablets in a small study

Bowel symptoms

Green tea beverage: preliminary evidence of shorter time to gastrointestinal function recovery after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea

Shorter time to gastrointestinal function recovery, including first flatus, first bowel movement, and tolerance of solid food after robotic or laparoscopic subtotal gastrectomy among people with stomach (gastric) cancer drinking green tea compared to potable water in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁸¹Liu D, Jing X et al. Impact of drinking Chinese green tea on postoperative short outcomes for gastric cancer: a randomized controlled trial. European Journal of Clinical Nutrition. 2021 Nov;75(11):1568-1577.

Green tea supplements: preliminary evidence of lower incidence and less severe diarrhea after radiotherapy among people with abdomen and pelvic malignancy treated with green tea tablets

Lower incidence and less severe diarrhea after 50 Gy radiotherapy among people with abdomen and pelvic malignancy treated with 450 mg green tea tablets for 5 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCT⁸²Emami H, Nikoobin F, Roayaei M, Ziya HR. Double-blinded, randomized, placebo-controlled study to evaluate the effectiveness of green tea in preventing acute gastrointestinal complications due to radiotherapy. Journal of Research in Medical Sciences. 2014 May;19(5):445-50.

Esophagitis

Preliminary evidence of less esophagitis during or after chemoradiotherapy among people with lung cancer treated with EGCG before or during chemoradiotherapy

Lower esophagitis grades after chemoradiation among people with unresectable stage 3 non-small-cell lung cancer or limited stage small-cell lung cancer treated with EGCG compared to conventional chemoradiation alone, with even better result among people treated with EGCG prophylactically compared to after the occurrence of esophagitis, in a small RCT⁸³Zhao H, Jia L et al. A prospective, three-arm, randomized trial of EGCG for preventing radiation-induced esophagitis in lung cancer patients receiving radiotherapy. Radiotherapy and Oncology. 2019 Aug;137:186-191.
Better Radiation Therapy Oncology Group (RTOG) and pain scores after concurrent or sequential chemo-radiotherapy or radiotherapy alone among people with stage 3 lung cancer and acute radiation-induced esophagitis treated with 440μmol/L EGCG 3 times a day at the onset of acute radiotherapy-induced esophagitis until 2 weeks after radiotherapy completion compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design⁸⁴Zhao H, Xie P et al. A prospective phase II trial of EGCG in treatment of acute radiation-induced esophagitis for stage III lung cancer. Radiotherapy and Oncology. 2015 Mar;114(3):351-6.
Regression of esophagitis to grade 0/1 in 92% of people and lower pain scores during chemotherapy (cisplatin and etoposide) given concurrently with radiation among people with surgically unresectable stage III non-small-cell lung cancer developing grade 2 esophagitis treated with an oral EGCG solution (swallowed) 3 times a day in a small uncontrolled trial⁸⁵Zhao H, Zhu W et al. A phase I study of concurrent chemotherapy and thoracic radiotherapy with oral epigallocatechin-3-gallate protection in patients with locally advanced stage III non-small-cell lung cancer. Radiotherapy and Oncology. 2014 Jan;110(1):132-6.

Vomiting

No evidence of an effect on vomiting after radiotherapy among people with abdomen and pelvic malignancy treated with green tea tablets in a small study

No evidence of an effect on vomiting after 50 Gy radiotherapy among people with abdomen and pelvic malignancy treated with 450 mg green tea tablets for 5 weeks compared to placebo in a small RCT⁸⁶Emami H, Nikoobin F, Roayaei M, Ziya HR. Double-blinded, randomized, placebo-controlled study to evaluate the effectiveness of green tea in preventing acute gastrointestinal complications due to radiotherapy. Journal of Research in Medical Sciences. 2014 May;19(5):445-50.

Oral symptoms

Preliminary evidence of better oral health scores after oral surgery among people with oral cancer rinsing their mouths with a green tea solution

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of decreasing mucositisinflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer-related pain scores over time during radiation treatment among people with head and neck cancer treated with an EGCG mouthwash

Pain

Preliminary evidence of less perception of pain although no evidence of an effect on analgesic use during days 1–4 after robotic or laparoscopic subtotal gastrectomy among people with stomach cancer drinking green tea

Skin and tissue side effects

Preliminary evidence of lower incidence of grade 2 or worse radiation-induced dermatitis and lower symptom indexes among people with breast cancer treated with an EGCG solution sprayed to the whole radiation field

Preliminary evidence of less severe acute radiation-induced skin reactions during whole-breast radiotherapy after surgery among people treated with NPE, a proprietary Camellia sinensis nonfermentatum extract

Lower incidence of grade 2 or worse radiation-induced dermatitis and lower symptom indexes among people with breast cancer treated with a 660 μmol/L EGCG solution sprayed to the whole radiation field from day 1 of the radiation until 2 weeks after radiation completion compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a mid-sized RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁹⁰Zhao H, Zhu W et al. Efficacy of epigallocatechin-3-gallate in preventing dermatitis in patients with breast cancer receiving postoperative radiotherapy: a double-blind, placebo-controlled, phase 2 randomized clinical trial. JAMA Dermatology. 2022 Jul 1;158(7):779-786.

Longer times to acute radiation-induced skin reactions (ARSR), a 50% lower risk of developing grade 2 or higher ARSR, and a weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward faster recovery from ARSR during whole-breast radiotherapy after surgery among people treated with NPE, a proprietary Camellia sinensis nonfermentatum extract (CSNF), with a CSNF gel 1 to 2 hours before each session on the irradiated fields and a CSNF lotion 7-day pretreatment before each radiation session, twice a day between RT sessions, and 4 to 8 weeks thereafter in a mid-sized observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods study⁹¹Näf G, Gasser UE et al. Prevention of acute radiation-induced skin reaction with NPE® Camellia sinensis nonfermentatum extract in female breast cancer patients undergoing postoperative radiotherapy: a single centre, prospective, open-label pilot study. International Journal of Breast Cancer. 2018 Jul 2;2018:2479274.

Other side effects

Preliminary evidence of shorter hospital stays after robotic or laparoscopic subtotal gastrectomy among people with stomach cancer drinking green tea

Preliminary evidence of comparable odor control from fungatingbreaking through the skin malignant wounds among people treated with either metronidazole powder or green tea bags as dressings

Side effects not specific to cancer

Strong evidenceconsistent, significant effects in several large (or at least one very large) well designed clinical studies or at least two meta-analyses of clinical studies of moderate or better quality (or one large meta-analysis) finding similar results (this is the CancerChoices definition; other researchers and studies may define this differently) of lower systolic and diastolic blood pressure among people drinking green tea compared to no green tea (not specific to cancer)

Preliminary evidence of lower depressive symptom scores and shorter reaction time of reward responsiveness among healthy people treated with green tea powder

Cardiovascular symptoms

Strong evidence of lower systolic and diastolic blood pressure among people drinking green tea compared to no green tea (not specific to cancer)

Lower systolic and diastolic blood pressure among people drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 13 meta-analyses⁹⁴Neyestani TR, Nikooyeh B. A comprehensive overview on the effects of green tea on anthropometric measures, blood pressure, glycemic and lipidemic status: An umbrella review and meta meta-analysis study. Nutrition, Metabolism, and Cardiovascular Diseases. 2022 Sep;32(9):2026-2040.
Lower systolic and diastolic blood pressure among people drinking green tea compared to no green tea in a meta-analysis of 13 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁹⁵Khalesi S, Sun J et al Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. European Journal of Nutrition. 2014 Sep;53(6):1299-311.
Lower systolic blood pressure among Japanese women and men with visceral fat-type obesity and baseline pressure of 130 mm Hg or higher drinking green tea containing 583 mg of catechins compared to 96 mg of catechins in a mid-sized RCT⁹⁶Nagao T, Hase T, Tokimitsu I. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity (Silver Spring). 2007 Jun;15(6):1473-83.

Depression

Preliminary evidence of lower depressive symptom scores and shorter reaction time of reward responsiveness among healthy people treated with green tea powder

Lower depressive symptom scores (Montgomery-Asberg depression rating scale and Hamilton Rating Scale for Depression) and shorter reaction time of reward responsiveness among healthy people treated with 400 mg green tea powder for 5 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCT⁹⁷Zhang Q, Yang H et al. Effect of green tea on reward learning in healthy individuals: a randomized, double-blind, placebo-controlled pilot study. Nutrition Journal. 2013 Jun 18;12:84.

Green tea extract combined with other therapies

Preliminary evidence of less diabetic peripheral neuropathydamage to the peripheral nerves outside the brain and spinal cord among people treated with DiVFuSS formulation (not specific to cancer)

Preliminary evidence of lower incidence of adverse events of grade 4 or higher and occurrence of increased serum creatinine (an indicator of kidney toxicity) during chemotherapy among people with metastatic colorectal cancer treated with MB-6

Preliminary evidence of higher hair density and hair diameter among people treated with BLH308, persimmon leaf formulated with green tea and sophora fruit (not specific to cancer)

DiVFuSS formulation of vitamins C, D3, and E (d-α tocopherol), zinc oxide, eicosapentaenoic acid, docosahexaenoic acid, α-lipoic acid (racemic mixture), coenzyme Q10, mixed tocotrienols/tocopherols, zeaxanthin, lutein, benfotiamine, N-acetyl cysteine, grape seed extract, resveratrol, turmeric root extract, green tea leaf, and Pycnogenol: preliminary evidence of less diabetic peripheral neuropathy among people treated with DiVFuSS formulation (not specific to cancer)

Less diabetic peripheral neuropathy among people treated with DiVFuSS formulation for 6 months compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects⁹⁸Chous AP, Richer SP, Gerson JD, Kowluru RA. The Diabetes Visual Function Supplement Study (DiVFuSS). British Journal of Ophthalmology. 2016 Feb;100(2):227-34.

MB-6, a preparation of fermented soybean extract, green tea extract, Antrodia camphorata mycelia, spirulina, grape seed extract, and curcumin extract: preliminary evidence of lower incidence of adverse events of grade 4 or higher and occurrence of increased serum creatinine (an indicator of kidney toxicity) during chemotherapy among people with metastatic colorectal cancer treated with MB-6

Lower incidence of side effects (adverse events, at least grade 4) and occurrence of increased serum creatinine (an indicator of kidney toxicity) during chemotherapy among people with metastatic colorectal cancer treated with MB-6 for 16 weeks compared to chemotherapy alone in a small RCT⁹⁹Chen WT, Yang TS et al. Effectiveness of a novel herbal agent MB-6 as a potential adjunct to 5-fluoracil-based chemotherapy in colorectal cancer. Nutrition Research. 2014 Jul;34(7):585-94.

BLH308, persimmon leaf formulated with green tea and sophora fruit: preliminary evidence of higher hair density and hair diameter among people treated with BLH308 (not specific to cancer)

Higher hair density and hair diameter among people treated with BLH308 for 24 weeks compared to placebo in a small RCT¹⁰⁰Ham S, Lee YI et al. Efficacy and safety of persimmon leaf formulated with green tea and sophora fruit extracts (BLH308) on hair growth: a randomized, double-blind, placebo-controlled clinical trial. Skin Research and Technology. 2023 Sep;29(9):e13448.

Also see separate reviews of products containing green tea extracts:

Pomi-T, a blend of pomegranate extracts, green tea extracts, turmeric, and broccoli extracts: Pomi-T ›
Zyflamend, a blend of rosemary, turmeric, ginger, holy basil, green tea, hu zhang, Chinese goldthread, barberry, oregano, and baikal skullcap: Zyflamend ›

Reducing cancer risk

Is green tea or EGCG linked to lower risks of developing cancer or of recurrence? We present the evidence.

Cancer as a whole

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of cancer as a whole among people drinking the highest quantities of green tea compared to the lowest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 3 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹⁰¹Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
No evidence of an effect on risk of cancer as a whole (3 studies) or cancer mortality (8 studies) among people without cancer at baseline drinking the highest levels of green tea compared to the lowest in meta-analyses of observational studies¹⁰²Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.
No evidence of an effect on cancer mortality among people in Asia without cancer at baseline drinking green tea compared to non-drinkers in a meta-analysis of 12 observational studies¹⁰³Shin S, Lee JE et al. Coffee and tea consumption and mortality from all causes, cardiovascular disease and cancer: a pooled analysis of prospective studies from the Asia Cohort Consortium. International Journal of Epidemiology. 2022 May 9;51(2):626-640.
About 10% lower risk of cancer mortality among women (but not men) in Japan without cancer at baseline drinking 1 to 4 cups of green tea per day compared to less than 1 cup in a meta-analysis of 8 observational studies¹⁰⁴Abe SK, Saito E et al; Research Group for the Development and Evaluation of Cancer Prevention Strategies in Japan. Green tea consumption and mortality in Japanese men and women: a pooled analysis of eight population-based cohort studies in Japan. European Journal of Epidemiology. 2019 Oct;34(10):917-926.

Bladder or urinary tract cancer

Insufficient (conflicting) evidence of an effect on risk of bladder cancer among people drinking green tea

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on risk of urinary tract cancer among people drinking green tea in a combined analysis of studies

Recurrence

Preliminary evidence of substantially lower risk of urinary tract recurrence among people with bladder cancer or urothelial cancer among nonsmokers, but not among people who had ever smoked, drinking green tea, with higher benefits among people drinking higher levels

74% lower risk of urinary tract recurrence among people with bladder cancer or urothelial cancer among nonsmokers, but not among people who had ever smoked, drinking 1–4 cups of green tea per day compared to less than one cup, and stronger benefits among people drinking more than 5 cups a day, including 80% lower risk of recurrence and lower risk of up-grading or up-staging in recurrent cancer, in a mid-sized observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods study¹⁰⁵Yasuda T, Miyata Y et al. High consumption of green tea suppresses urinary tract recurrence of urothelial cancer via down-regulation of human antigen-R expression in never smokers. In Vivo. 2018 Jul-Aug;32(4):721-729.

Cancer risk

Insufficient (conflicting) evidence of an effect on risk of bladder cancer among people drinking green tea

No evidence of an effect on risk of bladder cancer among people drinking the highest quantities of green tea compared to the lowest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 4 observational studies¹⁰⁶Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
No evidence of an effect on risk of bladder cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 5 observational studies¹⁰⁷Wu S, Li F et al. The association of tea consumption with bladder cancer risk: a meta-analysis. Asia-Pacific Journal of Clinical Nutrition. 2013;22(1):128-37.
19% lower risk of bladder cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 3 observational studies¹⁰⁸Wang X, Lin YW et al. A meta-analysis of tea consumption and the risk of bladder cancer. Urologia Internationalis. 2013;90(1):10-6.

No evidence of an effect on risk of urinary tract cancer among people drinking green tea in a combined analysis of studies

No evidence of an effect on risk of urinary tract cancer among people drinking the highest levels of green tea compared to the lowest in meta-analyses of 7 observational studies¹⁰⁹Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.

Breast cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of breast cancer recurrence among people drinking green tea, with some evidence that the benefit may be strongest in earlier stages of cancer

Modest and somewhat conflicting evidence of a slightly lower risk of breast cancer among people drinking green tea

Modest evidence of lower mammographic density (a risk factor for breast cancer) only among women aged 50 to 55, but no evidence of an effect on older healthy postmenopausal women treated with decaffeinated green tea extract capsules

Recurrence

Modest evidence of lower risk of breast cancer recurrence among people drinking green tea, with some evidence that the benefit may be strongest in earlier stages of cancer

About 15% lower risk of breast cancer recurrence among people drinking green tea compared to no green tea in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 7 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹¹⁰Gianfredi V, Nucci D et al. Green tea consumption and risk of breast cancer and recurrence—a systematic review and meta-analysis of observational studies. Nutrients. 2018 Dec 3;10(12):1886.
27% lower risk of breast cancer recurrence among people drinking more than 3 cups of green tea a day compared to less tea in a meta-analysis of 2 observational studies¹¹¹Ogunleye AA, Xue F, Michels KB. Green tea consumption and breast cancer risk or recurrence: a meta-analysis. Breast Cancer Research and Treatment. 2010 Jan;119(2):477-84.
44% lower risk of recurrence among people with stage 1 or 2 breast cancer among people drinking the highest levels of green tea compared to the lowest, but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. regarding recurrence overall, in a meta-analysis of 7 observational studies¹¹²Seely D, Mills EJ, Wu P, Verma S, Guyatt GH. The effects of green tea consumption on incidence of breast cancer and recurrence of breast cancer: a systematic review and meta-analysis. Integrative Cancer Therapies. 2005 Jun;4(2):144-55.

Breast cancer risk

Modest and somewhat conflicting evidence of a slightly lower risk of breast cancer among people drinking green tea

No evidence of an effect on risk of breast cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 6 observational studies¹¹³Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
14% lower risk of breast cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 16 observational studies¹¹⁴Wang Y, Zhao Y et al. A dose-response meta-analysis of green tea consumption and breast cancer risk. International Journal of Food Sciences and Nutrition. 2020 Sep;71(6):656-667.
17% lower risk of breast cancer among people drinking green tea compared to no green tea in a large meta-analysis of 14 observational studies¹¹⁵Yu S, Zhu L et al. Green tea consumption and risk of breast cancer: A systematic review and updated meta-analysis of case-control studies. Medicine (Baltimore). 2019 Jul;98(27).
15% lower risk of breast cancer among people drinking green tea compared to no green tea in a very large meta-analysis of 5 observational studies¹¹⁶Gianfredi V, Nucci D et al. Green tea consumption and risk of breast cancer and recurrence-a systematic review and meta-analysis of observational studies. Nutrients. 2018 Dec 3;10(12):1886.
19% lower risk of breast cancer among women drinking the highest level of green tea compared to the the lowest level in a meta-analysis of 14 observational studies¹¹⁷Najaf Najafi M, Salehi M, Ghazanfarpour M, Hoseini ZS, Khadem-Rezaiyan M. The association between green tea consumption and breast cancer risk: a systematic review and meta-analysis. Phytotherapy Research. 2018 Oct;32(10):1855-1864.
22% lower risk of breast cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 4 observational studies¹¹⁸Sun CL, Yuan JM, Koh WP, Yu MC. Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies. Carcinogenesis. 2006 Jul;27(7):1310-5.
No evidence of an effect on risk of breast cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 7 observational studies¹¹⁹Seely D, Mills EJ, Wu P, Verma S, Guyatt GH. The effects of green tea consumption on incidence of breast cancer and recurrence of breast cancer: a systematic review and meta-analysis. Integrative Cancer Therapies. 2005 Jun;4(2):144-55.

Mammographic density, a risk factor for breast cancer

Modest evidence of lower mammographic density only among women aged 50 to 55, but no evidence of an effect on older healthy postmenopausal women treated with decaffeinated green tea extract capsules

Lower mammographic density only among women aged 50 to 55 with heterogeneously dense or extremely dense breast tissue, but no evidence of an effect on older healthy postmenopausal women treated with decaffeinated green tea extract capsules containing 1,315 mg total catechins including 843 mg EGCG for 12 months compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹²⁰Samavat H, Ursin G et al. A randomized controlled trial of green tea extract supplementation and mammographic density in postmenopausal women at increased risk of breast cancer. Cancer Prevention Research (Philadelphia). 2017 Dec;10(12):710-718.

Colorectal cancer

Insufficient evidence of an effect on risk of colorectal cancer among people drinking green tea

Preliminary evidence of fewer colorectal adenomas among people with colon adenomas treated with green tea extract for 12 months or longer

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of lower levels of rectal DNA methyltransferase, a risk factor for colorectal cancer, among people with low plasma selenium treated with green tea capsules

Preliminary evidence of lower disease activity indices and higher remission rates among people with mild to moderate ulcerative colitis, a risk factor for colon cancer, treated with oral Polyphenon E

Colorectal cancer risk

Green tea beverage: insufficient evidence of an effect on risk of colorectal cancer among people drinking green tea

No evidence of an effect on risk of colon cancer (8 studies), colorectal cancer (8 studies), or rectal cancer (8 studies) among people drinking the highest quantities of green tea compared to the lowest in meta-analysesstatistical analyses that combine the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹²¹Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
2% lower risk of colorectal cancer among people drinking each cup of green tea compared to no green tea in a meta-analyses of 29 observational studies¹²²Chen Y, Wu Y et al. An inverse association between tea consumption and colorectal cancer risk. Oncotarget. 2017 Jun 6;8(23):37367-37376.
No evidence of an effect on risk of colorectal cancer among people drinking the highest levels compared to the lowest in a very large meta-analysis of 6 observational studies¹²³Wang ZH, Gao QY, Fang JY. Green tea and incidence of colorectal cancer: evidence from prospective cohort studies. Nutrition and Cancer. 2012;64(8):1143-52.
No evidence of an effect on risk of colorectal cancer among people drinking the highest levels of green tea compared to the lowest levels of no green tea in a large meta-analysis of 13 observational studies¹²⁴Wang XJ, Zeng XT et al. Association between green tea and colorectal cancer risk: a meta-analysis of 13 case-control studies. Asian Pacific Journal of Cancer Prevention. 2012;13(7):3123-7.
18% lower risk of colorectal cancer, especially colon cancer, among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 8 observational studies¹²⁵ Sun CL, Yuan JM, Koh WP, Yu MC. Green tea, black tea and colorectal cancer risk: a meta-analysis of epidemiologic studies. Carcinogenesis. 2006 Jul;27(7):1301-9.

Green tea supplements or EGCG: preliminary evidence of fewer colorectal adenomas among people with colon adenomas treated with green tea extract for 12 months or longer

A very weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward fewer colorectal adenomas among people with colon adenomas treated with green tea extract standardized to 150 mg of EGCG twice a day for 3 years compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹²⁶Seufferlein T, Ettrich TJ et al. Green tea extract to prevent colorectal adenomas, results of a randomized, placebo-controlled clinical trial. American Journal of Gastroenterology. 2022 Jun 1;117(6):884-894.
Fewer metachronous adenomas and relapsed adenomas among people who had undergone complete removal of colorectal adenomas by endoscopic polypectomy treated with 0.9 g green tea extract per day for 12 months compared to no supplementation in a mid-sized RCT¹²⁷Shin CM, Lee DH et al. Green tea extracts for the prevention of metachronous colorectal polyps among patients who underwent endoscopic removal of colorectal adenomas: a randomized clinical trial. Clinical Nutrition. 2018 Apr;37(2):452-458.
Fewer and smaller metachronous adenomas after removal of colorectal adenomas and 1 year of no recurrence among people treated with 1.5 g green tea extracts per day for 12 months compared to no green tea extracts in a mid-sized RCT¹²⁸Shimizu M, Fukutomi Y et al. Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study. Cancer Epidemiology, Biomarkers & Prevention. 2008 Nov;17(11):3020-5.
No evidence of an effect on number of aberrant crypt foci (ACF), ACF burden, or adenoma recurrence rate among people with rectal ACF treated with oral Poly E (780 mg EGCG) daily for 6 months compared to placebo in a small RCT¹²⁹Sinicrope FA, Viggiano TR et al. Randomized phase II trial of Polyphenon E versus placebo in patients at high risk of recurrent colonic neoplasia. Cancer Prevention Research (Phila). 2021 May;14(5):573-580.

Weak evidence of lower levels of rectal DNA methyltransferase, a risk factor for colorectal cancer, among people with low plasma selenium treated with green tea capsules

Lower levels of rectal DNA methyltransferase (DNMT1) among people with plasma selenium less than or equal to 1.36 µmol/liter treated with green tea capsules containing 800 mg EGCG compared to baseline in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design¹³⁰Hu Y, McIntosh GH et al. Supplementation with Brazil nuts and green tea extract regulates targeted biomarkers related to colorectal cancer risk in humans. British Journal of Nutrition. 2016 Dec;116(11):1901-1911.

Preliminary evidence of lower disease activity indices and higher remission rates among people with mild to moderate ulcerative colitis, a risk factor for colon cancer, treated with oral Polyphenon E

Lower disease activity indices and higher remission rates among people with mild to moderate ulcerative colitis refractory to 5-aminosalicylic and/or azathioprine treated with oral Polyphenon E containing 400 mg or 800 mg of total EGCG daily compared to placebo in a small RCT¹³¹Dryden GW, Lam A, Beatty K, Qazzaz HH, McClain CJ. A pilot study to evaluate the safety and efficacy of an oral dose of (-)-epigallocatechin-3-gallate-rich Polyphenon E in patients with mild to moderate ulcerative colitis. Inflammatory Bowel Disease. 2013 Aug;19(9):1904-12.

Gastrointestinal cancer

Colorectal cancer and pancreatic cancer are listed separately.

Insufficient (conflicting) evidence of an effect on risk of gallbladder cancer among people drinking green tea

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of lower risk of esophageal cancer among women drinking green tea, but not men

No evidence of an effect on esophageal precancerous lesions and abnormal cell proliferation among people treated with decaffeinated green tea supplements in a large study

Good evidence of a moderately lower risk of liver cancer among people drinking green tea

Modest but conflicting evidence of lower risk of stomach cancer among people drinking green tea

Preliminary evidence of lower risk of chronic atrophic gastritis (CAG), a precancerous lesion of the stomach, among people drinking large quantities of green tea

Preliminary evidence of lower fumonisin B1, which induces DNA fragmentation and is linked to liver cancer (hepatocellular carcinoma) and esophageal cancer, among people exposed to FB1 and treated with green tea polyphenols

Gallbladder or biliary tract cancer

Insufficient (conflicting) evidence of an effect on risk of gallbladder cancer among people drinking green tea

No evidence of an effect on risk of gallbladder cancer among people drinking the highest quantities of green tea compared to the lowest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 2 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹³²Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
33% lower risk of biliary tract cancer among people drinking the highest quantities of green tea compared to the lowest in a very large observational study¹³³Makiuchi T, Sobue T et al. Association between green tea/coffee consumption and biliary tract cancer: a population-based cohort study in Japan. Cancer Science. 2016 Jan;107(1):76-83.

Esophageal cancer

Good evidence of lower risk of esophageal cancer among women drinking green tea, but not men

21% lower risk of esophageal cancer among women, but not men, drinking more cups of green tea compared to fewer cups in a very large meta-analysis of 14 observational studies¹³⁴Zhao H, Mei K, Yang L, Liu X, Xie L. Green tea consumption and risk for esophageal cancer: a systematic review and dose-response meta-analysis. Nutrition. 2021 Jul-Aug;87-88:111197.
35% lower risk of esophageal cancer among people drinking green tea compared to no green tea, with stronger effects among women or in Asian vs. non-Asian countries in a meta-analysis of 20 observational studies¹³⁵Yi Y, Liang H et al. Green tea consumption and esophageal cancer risk: a meta-analysis. Nutrition and Cancer. 2020;72(3):513-521.
54% lower risk of esophageal cancer among women drinking the highest levels of green tea compared to the lowest levels or no green tea, but no evidence of an effect among men in a meta-analysis of 12 observational studies¹³⁶Sang LX, Chang B, Li XH, Jiang M. Green tea consumption and risk of esophageal cancer: a meta-analysis of published epidemiological studies. Nutrition and Cancer. 2013;65(6):802-12.
A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower risk of esophageal cancer among people drinking the highest levels of green tea compared to the lowest levels or no green tea in a meta-analysis of 24 observational studies¹³⁷Zheng JS, Yang J et al. Effects of green tea, black tea, and coffee consumption on the risk of esophageal cancer: a systematic review and meta-analysis of observational studies. Nutrition and Cancer. 2013;65(1):1-16.
Weak trends toward lower risk of esophageal cancer among people drinking green tea compared to no green tea, and much stronger effects among women, in meta-analyses of 10 observational studies¹³⁸Zheng P, Zheng HM, Deng XM, Zhang YD. Green tea consumption and risk of esophageal cancer: a meta-analysis of epidemiologic studies. BMC Gastroenterology. 2012 Nov 21;12:165.
A weak trend toward higher risk of esophageal cancer among people drinking the highest levels of green tea compared to the lowest levels in a meta-analysis of 2 observational studies¹³⁹Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.

No evidence of an effect on esophageal precancerous lesions and abnormal cell proliferation among people treated with decaffeinated green tea supplements in a large study

No evidence of an effect on esophageal precancerous lesions and abnormal cell proliferation among people treated with 5 mg decaffeinated green tea supplement a day for 12 months compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁴⁰Wang LD, Zhou Q et al. Intervention and follow-up on human esophageal precancerous lesions in Henan, northern China, a high-incidence area for esophageal cancer. Gan To Kagaku Ryoho. 2002 Feb;29 Suppl 1:159-72.

Liver cancer

Good evidence of a moderately lower risk of liver cancer among people drinking green tea

20% lower risk of liver cancer (hepatocellular carcinoma) among people drinking higher levels of green tea compared to lower levels in a very large meta-analysis of 18 observational studies¹⁴¹Yu J, Liang D et al. Coffee, green tea intake, and the risk of hepatocellular carcinoma: a systematic review and meta-analysis of observational studies. Nutrition and Cancer. 2023;75(5):1295-1308.
12% lower risk of liver cancer, especially for women, among people drinking the highest levels of green tea compared to the lowest levels or no green tea in a very large meta-analysis of 9 observational studies¹⁴²Huang YQ, Lu X et al. Green tea and liver cancer risk: a meta-analysis of prospective cohort studies in Asian populations. Nutrition. 2016 Jan;32(1):3-8.
No evidence of an effect on risk of liver cancer among people drinking the highest levels of green tea compared to the lowest levels in a meta-analysis of 5 observational studies¹⁴³Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
38% lower risk of liver cancer among people drinking the highest quantities of green tea compared to no green tea in a meta-analysis of 6 observational studies¹⁴⁴Ni CX, Gong H et al. Green tea consumption and the risk of liver cancer: a meta-analysis. Nutrition and Cancer. 2017 Feb-Mar;69(2):211-220.
21% lower risk of primary liver cancer among people drinking green tea compared to no green tea, with stronger effects among women, in a meta-analysis of 8 observational studies¹⁴⁵Fon Sing M, Yang WS, Gao S, Gao J, Xiang YB. Epidemiological studies of the association between tea drinking and primary liver cancer: a meta-analysis. European Journal of Cancer Prevention. 2011 May;20(3):157-65.

Stomach (gastric) cancer

Modest but conflicting evidence of lower risk of stomach cancer among people drinking green tea

No evidence of an effect on risk of stomach cancer among people drinking the highest quantities of green tea compared to the lowest in a meta-analysis of 4 observational studies¹⁴⁶Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
19% lower risk of stomach cancer among women (3 studies) but not men (2 studies) drinking green tea compared to no tea in meta-analyses of observational studies¹⁴⁷Bae JM. Green tea consumption and stomach cancer risk in women: a meta-analysis of population-based cohort studies. Cancer Research and Treatment. 2021 Jan;53(1):289-290.
12% lower risk of stomach cancer among people drinking green tea compared to no green tea in a meta-analysis of 16 observational studies¹⁴⁸Poorolajal J, Moradi L, Mohammadi Y, Cheraghi Z, Gohari-Ensaf F. Risk factors for stomach cancer: a systematic review and meta-analysis. Epidemiology and Health. 2020;42:e2020004.
21% lower risk of stomach cancer among people drinking 6 or more cups of green tea a day compared to no green tea in a meta-analysis of 8 observational studies¹⁴⁹Huang Y, Chen H et al. Association between green tea intake and risk of gastric cancer: a systematic review and dose-response meta-analysis of observational studies. Public Health Nutrition. 2017 Dec;20(17):3183-3192.
41% lower risk of stomach cancer among people drinking green tea for 25 years or more compared to less than 2 years in a meta-analysis of 3 observational studies¹⁵⁰Huang Y, Chen H et al. Association between green tea intake and risk of gastric cancer: a systematic review and dose-response meta-analysis of observational studies. Public Health Nutrition. 2017 Dec;20(17):3183-3192.
18% lower risk of stomach cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 13 observational studies¹⁵¹Myung SK, Bae WK et al. Green tea consumption and risk of stomach cancer: a meta-analysis of epidemiologic studies. International Journal of Cancer. 2009 Feb 1;124(3):670-7.
No evidence of an effect on risk of stomach cancer among people drinking the highest levels of green tea compared to the lowest in a very large meta-analysis of 14 observational studies¹⁵²Zhou Y, Li N et al. Green tea and gastric cancer risk: meta-analysis of epidemiologic studies. Asia-Pacific Journal of Clinical Nutrition. 2008;17(1):159-65.

Preliminary evidence of lower risk of chronic atrophic gastritis (CAG), a precancerous lesion of the stomach, among people drinking large quantities of green tea

Lower risk of chronic atrophic gastritis among people drinking 10 or more cups of green tea per day compared to less than 10 cups in a mid-sized observational study¹⁵³Shibata K, Moriyama M et al. Green tea consumption and chronic atrophic gastritis: a cross-sectional study in a green tea production village. Journal of Epidemiology. 2000 Sep;10(5):310-6.

Biomarkers of fumonisin B1

Preliminary evidence of lower fumonisin B1 (FB1), which induces DNA fragmentation and is linked to liver cancer (hepatocellular carcinoma) and esophageal cancer, among people exposed to FB1 and treated with green tea polyphenols

Lower urinary fumonisin B1 (FB1) among people exposed to FB1 and treated with 1,000 mg green tea polyphenols for 1 month or longer or 1,000 mg green tea polyphenols for 3 months or longer compared to placebo in a mid-sized RCT¹⁵⁴Xue KS, Tang L et al. Mitigation of fumonisin biomarkers by green tea polyphenols in a high-risk population of hepatocellular carcinoma. Scientific Reports. 2015 Dec 2;5:17545.

Gynecological cancer

Ovarian cancer is listed separately.

No evidence of an effect on risk of gynecological cancer as a whole among people treated with green tea extracts in a combined analysis of studies

No evidence of an effect on HPV infection and low-grade CIN1, risk factors for cervical cancer, among women treated with Polyphenon E in a small study

Good evidence of moderately lower risk of endometrial cancer among people drinking green tea

Preliminary evidence of substantially higher response of human papilloma virus-infected lesions, a risk factor for genital cancer, among people treated with topical Poly E ointment and/or oral EGCG capsules

Gynecological cancer as a whole

No evidence of an effect on risk of gynecological cancer as a whole among people treated with green tea extracts in a combined analysis of studies

No evidence of an effect on risk of gynecological cancer as a whole among people treated with green tea extracts compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 2 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁵⁵Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.

Cervical cancer

Persistent human papillomavirus (HPV) infection and low-grade cervical intraepithelial neoplasia (CIN1), risk factors for cervical cancer: no evidence of an effect on HPV infection and low-grade CIN1 among women treated with Polyphenon E in a small study

No evidence of an effect on HPV infection and low-grade CIN1 among women treated with Polyphenon E containing 800 mg EGCG compared to placebo in a small RCT¹⁵⁶Garcia FA, Cornelison T et al. Results of a phase II randomized, double-blind, placebo-controlled trial of Polyphenon E in women with persistent high-risk HPV infection and low-grade cervical intraepithelial neoplasia. Gynecologic Oncology. 2014 Feb;132(2):377-82.

Endometrial cancer

Good evidence of moderately lower risk of endometrial cancer among people drinking green tea

23% lower risk of endometrial cancer among people drinking the highest levels of green tea compared to the lowest in meta-analyses of 5 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹⁵⁷Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.
22% lower risk of endometrial cancer among people drinking the highest levels of green tea compared to the lowest in meta-analyses of 2 observational studies¹⁵⁸Zhou Q, Li H et al. Green tea, black tea consumption and risk of endometrial cancer: a systematic review and meta-analysis. Archives of Gynecology and Obstetrics. 2016 Jan;293(1):143-155.
22% lower risk of endometrial cancer among people drinking green tea compared to no green tea in a meta-analysis of 6 observational studies¹⁵⁹Butler LM, Wu AH. Green and black tea in relation to gynecologic cancers. Molecular Nutrition & Food Research. 2011 Jun;55(6):931-40.

Persistent HPV infection

Substantially higher response of human papilloma virus-infected lesions among people treated with topical Poly E ointment and/or oral EGCG capsules every day for 8 to 12 weeks compared to untreated controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial¹⁶⁰Ahn WS, Yoo J et al. Protective effects of green tea extracts (Polyphenon E and EGCG) on human cervical lesions. European Journal of Cancer Prevention. 2003 Oct;12(5):383-90.

Head, neck, and oral cancer

Preliminary evidence of lower risk of oral cancer among people drinking green tea

Weak evidence of a higher clinical response of oral premalignant lesions among people treated with green tea extract, with evidence of stronger responses at higher doses

Green tea beverage

Preliminary evidence of lower risk of oral cancer among people drinking green tea

Weak evidence of lower risk of oral cancer among people drinking the highest quantities of green tea compared to the lowest in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 3 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹⁶¹Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
20% lower risk of oral cancer among people drinking the highest levels of green tea compared to the lowest in a meta-analysis of 19 observational studies¹⁶²Wang W, Yang Y, Zhang W, Wu W. Association of tea consumption and the risk of oral cancer: a meta-analysis. Oral Oncology. 2014 Apr;50(4):276-81.

Green tea supplements

Weak evidence of a higher clinical response of oral premalignant lesions among people treated with green tea extract, with evidence of stronger responses at higher doses

A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward higher clinical response rate (with stronger responses at higher doses) but no evidence of an effect on development of oral cancer among people with high-risk oral premalignant lesions treated with 500, 750, or 1,000 mg/m2 green tea extract 3 times a day for 12 weeks compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁶³Tsao AS, Liu D et al. Phase II randomized, placebo-controlled trial of green tea extract in patients with high-risk oral premalignant lesions. Cancer Prevention Research (Philadelphia). 2009 Nov;2(11):931-41.
A weak trend toward a higher clinical response of oral premalignant lesions, with stronger responses at higher doses, but no evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on histologicalrelating to the study of the structure of cells and tissue seen under a microscope response among people treated with either 500 mg/m2, 750 mg/m2 or 1000 mg/m2 green tea extract after meals 3 times a day for 12 weeks compared to placebo in a small RCT¹⁶⁴Tsao AS, Liu D et al. Improvement of clinical response and biomarkers by Camellia sinensis (green tea) extract in patients with high-risk oral premalignant lesions. Focus on Alternative and Complementary Therapies. 2010;15(2); Tsao AS, Liu D et al. Phase II randomized, placebo-controlled trial of green tea extract in patients with high-risk oral premalignant lesions. Cancer Prevention Research. 2009;2(11):931-41.

Leukemia

Preliminary evidence of lower human T-cell lymphotropic virus type 1 (HTLV-1), a risk factor for adult T-cell leukemia (ATL), among asymptomatic HTLV-1 carriers treated with green tea extract powder

Lung cancer

Modest evidence of moderately lower risk of lung cancer among people drinking green tea

Lymphoma and lymphoid neoplasms

Modest evidence of a moderately lower risk of lymphoid neoplasms (lymphoma, myeloma, and lymphoid leukemia) among people drinking green tea

Melanoma and other skin cancers

No evidence of an effect on symptoms among people with recessive dystrophic epidermolysis bullosa (RDEB), a risk factor for fatal skin cancers, treated with oral EGCG in a small study

Insufficient (conflicting) evidence of protection against sunburn (UV-induced erythema), a risk factor for skin cancer, among people treated with an extract of green tea or one of its constituents

Preliminary evidence of less sunburn (UV-induced erythema) or DNA damage among people treated with topical polyphenols including EGCG from green tea

Dystrophic epidermolysis bullosa

No evidence of an effect on symptoms among people with recessive dystrophic epidermolysis bullosa (RDEB), a risk factor for fatal skin cancers, treated with oral EGCG in a small study

No evidence of an effect on symptoms among people with recessive dystrophic epidermolysis bullosa (RDEB), a risk factor for fatal skin cancers, treated with oral EGCG for 4 months compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁷²Chiaverini C, Roger C et al. Oral epigallocatechin-3-gallate for treatment of dystrophic epidermolysis bullosa: a multicentre, randomized, crossover, double-blind, placebo-controlled clinical trial. Orphanet Journal of Rare Diseases. 2016 Mar 25;11:31.

Ultraviolet-induced redness (erythema, or sunburn) or damage

Oral green tea supplements: insufficient (conflicting) evidence of protection against sunburn (UV-induced erythema), a risk factor for skin cancer, among people treated with an extract of green tea or one of its constituents

No evidence of protection against UV-induced erythema among people with Fitzpatric skin type II or III treated with 400 or 800 mg oral EGCG or the equivalent dose from Polyphenon E per day for 4 weeks compared to placebo in an RCT¹⁷³Chow HH, Cai Y et al. Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and Polyphenon E in healthy individuals. Clinical Cancer Research. 2003 Aug 15;9(9):3312-9.
Less redness (erythema), fewer sunburned cells, and less damage to epidermal Langerhans cells after exposure to UVB radiation among people treated with an extract of green tea or one of its constituents (EGCG, ECG, EGC, or EC, with the strongest effects from oral EGCG and ECG) compared to controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial¹⁷⁴Elmets CA, Singh D et al. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. Journal of the American Academy of Dermatology. 2001 Mar;44(3):425-32.

Topical green tea extracts, including EGCG: preliminary evidence of less sunburn (UV-induced erythema) or DNA damage among people treated with topical polyphenols including EGCG from green tea

Less erythema after exposure to UVB radiation among people treated with topical application of 3 mg EGCG/2.5 cm2 before UVB exposure compared to controls in a small RCT¹⁷⁵Katiyar SK, Matsui MS, Elmets CA, Mukhtar H. Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin. Photochemistry and Photobiology. 1999 Feb;69(2):148-53.
Less ultraviolet (UV) light-induced DNA damage as measured by cyclobutane pyrimidine dimers formed in the skin after exposure to UVB among people treated with topical polyphenols from green tea (approximately 1 mg/cm2 of skin area) 20 minutes before exposure compared to no treatment, with stronger effects at higher doses of UV light, in a small controlled trial¹⁷⁶Katiyar SK, Perez A, Mukhtar H. Green tea polyphenol treatment to human skin prevents formation of ultraviolet light B-induced pyrimidine dimers in DNA. Clinical Cancer Research. 2000 Oct;6(10):3864-9.

Multiple myeloma

Weak evidence of lower risk of multiple myeloma among people drinking green tea

Ovarian cancer

Insufficient evidence of an effect on recurrence among women with serous or endometrioid ovarian cancer drinking double-brewed green tea

Good evidence of moderately lower risk of ovarian cancer among people drinking green tea

Recurrence

Insufficient evidence of an effect on recurrence among women with serous or endometrioid ovarian cancer drinking double-brewed green tea

Only 5 of 16 women remained free of recurrence 18 months after complete response following debulking surgery followed by 6 to 8 cycles of platinum/taxane chemotherapy among women with FIGO stage 3–4 serous or endometrioid ovarian cancer drinking 500 mL double-brewed green tea a day for 18 months or until recurrence in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design; the researchers did not conclude that double-brewed green tea is a promising maintenance intervention for this population¹⁷⁸Trudel D, Labbé DP et al. A two-stage, single-arm, phase II study of EGCG-enriched green tea drink as a maintenance therapy in women with advanced stage ovarian cancer. Gynecologic Oncology. 2013 Nov;131(2):357-61.

Cancer risk

Good evidence of moderately lower risk of ovarian cancer among people drinking green tea

36% lower risk of ovarian cancer among people drinking the highest levels of green tea compared to the lowest in meta-analysesstatistical analyses that combine the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 5 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹⁷⁹Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.
39% lower risk of ovarian cancer among women drinking higher levels of green tea compared to lower levels in a meta-analysis of 97 observational studies¹⁸⁰Khodavandi A, Alizadeh F, Razis AFA. Association between dietary intake and risk of ovarian cancer: a systematic review and meta-analysis. European Journal of Nutrition. 2021 Jun;60(4):1707-1736.
36% lower risk of ovarian cancer among people drinking green tea compared to no green tea, with the lowest risks correlating with highest intake, in a meta-analysis of 14 observational studies¹⁸¹Zhang D, Kaushiva A, Xi Y, Wang T, Li N. Non-herbal tea consumption and ovarian cancer risk: a systematic review and meta-analysis of observational epidemiologic studies with indirect comparison and dose-response analysis. Carcinogenesis. 2018 May 28;39(6):808-818.
19% lower risk of ovarian cancer among people drinking green tea compared to no green tea in a meta-analysis of 6 observational studies¹⁸²Gao M, Ma W et al. Meta-analysis of green tea drinking and the prevalence of gynecological tumors in women. Asia-Pacific Journal of Public Health. 2013 Jul;25(4 Suppl):43S-8S.
34% lower risk of ovarian cancer among people drinking green tea compared to no green tea in a meta-analysis of 4 observational studies¹⁸³Butler LM, Wu AH. Green and black tea in relation to gynecologic cancers. Molecular Nutrition & Food Research. 2011 Jun;55(6):931-40.

Pancreatic cancer

No evidence of an effect on risk of pancreatic cancer among people drinking green tea in combined analyses of studies

Prostate cancer

Preliminary (conflicting) evidence of lower risk of prostate cancer among people drinking green tea

Modest but conflicting evidence of lower risk of prostate cancer among people treated with green tea extracts

Green tea beverage: preliminary (conflicting) evidence of lower risk of prostate cancer among people drinking green tea

No evidence of an effect on risk of prostate cancer among people drinking the highest levels of green tea compared to the lowest levels in a meta-analysisa statistical analysis that combines the results of two or more research studies; the results of smaller research studies addressing the same or similar questions can be analyzed as though they are one bigger, more powerful study of 4 observationala type of study in which individuals are observed or certain outcomes are measured, but no attempt is made to affect the outcome (for example, no treatment is given); an example is a study that records people’s diets, but doesn’t try to alter their diets, and looks for patterns of disease or other outcomes related to different foods studies¹⁸⁶Zhao LG, Li ZY et al. Tea drinking and risk of cancer incidence: a meta-analysis of prospective cohort studies and evidence evaluation. Advanced Nutrition. 2021 Mar 31;12(2):402-412.
27% lower risk of prostate cancer among people drinking the highest levels of green tea compared to the lowest in meta-analyses of 13 observational studies¹⁸⁷Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.
A weak trend toward lower risk of prostate cancer among people with the highest intake of green tea compared to the lowest in a meta-analysis of 7 observational studies¹⁸⁸Guo Y, Zhi F et al. Green tea and the risk of prostate cancer: a systematic review and meta-analysis. Medicine (Baltimore). 2017 Mar;96(13):e6426.
A weak trendan apparent change due to a therapy, close to but not achieving full statistical significance (this is the CancerChoices definition; other researchers and studies may define this differently toward lower risk of prostate cancer among people in Asia drinking the highest levels of green tea compared to the lowest in a meta-analysis of 4 observational studies¹⁸⁹Zheng J, Yang B et al. Green tea and black tea consumption and prostate cancer risk: an exploratory meta-analysis of observational studies. Nutrition and Cancer. 2011;63(5):663-72.

Green tea extracts or components: modest but conflicting evidence of lower risk of prostate cancer among people treated with green tea extracts

Lower risk of prostate cancer among people treated with green tea catechins compared to placeboa pill, medicine, or procedure—thought to be both harmless and ineffective—prescribed for the psychological benefit to the patient or as a sham treatment in a study to allow a comparison to a therapy of interest in a meta-analysis of 3 RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁹⁰Liu S, Chen J, Wang Y, Xu Y. Effect of dietary antioxidants on the risk of prostate cancer. Systematic review and network meta-analysis. Nutrición Hospitalaria. 2023 Jun 21;40(3):657-667.
No evidence of an effect on risk of prostate cancer among people at high risk of prostate cancer treated with green tea extracts compared to placebo in a meta-analysis of 3 RCTs¹⁹¹Filippini T, Malavolti M et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database of Systematic Reviews. 2020 Mar 2;3(3):CD005004.
72% lower risk of prostate cancer among people with high-grade prostatic intraepithelial neoplasia (HGPIN) treated with green tea catechins compared to placebo in a meta-analysis of 3 RCTs¹⁹²Guo Y, Zhi F et al. Green tea and the risk of prostate cancer: a systematic review and meta-analysis. Medicine (Baltimore). 2017 Mar;96(13):e6426.
59% lower risk of prostate cancer among men with high-grade prostate intraepithelial neoplasia or atypical small acinar proliferation but without prostate cancer at baseline treated with green tea catechins compared to placebo in a meta-analysis of 4 RCTs¹⁹³Perletti G, Magri V, Vral A, Stamatiou K, Trinchieri A. Green tea catechins for chemoprevention of prostate cancer in patients with histologically-proven HG-PIN or ASAP. Concise review and meta-analysis. Archivio Italiano di Urologica e Nefrologica. 2019 Oct 2;91(3).
61% lower risk of prostate cancer among people with high-grade prostatic intraepithelial neoplasia (HGPIN) with intake of green tea catechins compared to placebo in a meta-analysis of 2 RCTs¹⁹⁴Cui K, Li X et al. Chemoprevention of prostate cancer in men with high-grade prostatic intraepithelial neoplasia (HGPIN): a systematic review and adjusted indirect treatment comparison. Oncotarget. 2017 May 30;8(22):36674-36684.

Thyroid cancer

No evidence of an effect on risk of thyroid cancer among people drinking green tea in a combined analysis of studies

Green tea or EGCE combined with other therapies

Preliminary evidence of higher clinical response rate among people with oral potentially malignant disorders treated with both topical and systemic green tea extract green tea extract and curcumin

Weak evidence of clinical response among people with advanced premalignant lesions (APL) of the oral cavity and larynx treated with Polyphenon E and erlotinib

Preliminary evidence of lower risk of recurrence among people with resected colon cancer or prior polypectomy treated with flavonoid tablets containing apigenin and epigallocatechin-gallate

Weak evidence of less redness/redness and the accompanying inflammation after exposure to ultraviolet radiation, risk factors for skin cancer, among healthy people treated with green tea catechins and vitamin C

Curcumin and green tea extract: preliminary evidence of higher clinical response rate among people with oral potentially malignant disorders treated with both topical and systemic green tea extract green tea extract and curcumin

Higher clinical response rate among people with oral potentially malignant disorders treated with both 800 mg topical + systemic green tea extract per day and 950 mg topical + systemic curcumin per day for 3 months compared to either green tea extract or curcumin alone in a small RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects¹⁹⁶Neetha MC, Panchaksharappa MG, Pattabhiramasastry S, Shivaprasad NV, Venkatesh UG. Chemopreventive synergism between green tea extract and curcumin in patients with potentially malignant oral disorders: a double-blind, randomized preliminary study. Journal of Contemporary Dental Practice. 2020 May 1;21(5):521-531.

Polyphenon E (PPE) and erlotinib: weak evidence of clinical response among people with advanced premalignant lesions (APL) of the oral cavity and larynx treated with Polyphenon E and erlotinib

47% pathologic complete response, 18% pathologic partial response, and 66.3% 5-year cancer-free survival among people with advanced premalignant lesions (APL) of the oral cavity and larynx treated with 200 mg PPE 3 times a day and dose escalation of erlotinib for 6 months in a small uncontrolled triala study in which a therapy is used, but without a comparison group against which to judge outcomes; an uncontrolled trial is considered a weak study design¹⁹⁷Shin DM, Nannapaneni S et al. Phase Ib study of chemoprevention with green tea Polyphenon e and erlotinib in patients with advanced premalignant lesions (APL) of the head and neck. Clinical Cancer Research. 2020 Nov 15;26(22):5860-5868.

Flavonoid mixture including apigenin and epigallocathechin-gallat (EGC): preliminary evidence of lower risk of recurrence among people with resected colon cancer or prior polypectomy treated with flavonoid tablets containing apigenin and epigallocatechin-gallate

Lower risk of recurrence among people with resected colon cancer or prior polypectomy treated with 2 flavonoid tablets (10 mg apigenin and 10 mg epigallocatechin-gallate per tablet) for 2 to 5 years compared to controls in a small controlled triala study design in which people are assigned to either an experimental group or a control group to compare the outcomes from different treatment; assignment is not random, and so this is not as strong a study design as a randomized controlled trial, but still stronger than an uncontrolled trial¹⁹⁸Hoensch H, Groh B, Edler L, Kirch W. Prospective cohort comparison of flavonoid treatment in patients with resected colorectal cancer to prevent recurrence. World Journal of Gastroenterology. 2008 Apr 14;14(14):2187-93.

Green tea and vitamin C: weak evidence of less redness/redness and the accompanying inflammation after exposure to ultraviolet radiation, risk factors for skin cancer, among healthy people treated with green tea catechins vitamin C

Less redness (erythema) and the accompanying inflammation (12-hydroxyeicosatetraenoic acid) after exposure to UV radiation among healthy people treated with low-dose (540 mg) green tea catechins and 50 mg vitamin C daily for 12 weeks compared to baseline in a small uncontrolled trial¹⁹⁹Rhodes LE, Darby G et al. Oral green tea catechin metabolites are incorporated into human skin and protect against UV radiation-induced cutaneous inflammation in association with reduced production of pro-inflammatory eicosanoid 12-hydroxyeicosatetraenoic acid. British Journal of Nutrition. 2013 Sep 14;110(5):891-900.

Also see separate reviews of products containing green tea extracts:

Pomi-T, a blend of pomegranate extracts, green tea extracts, turmeric, and broccoli extracts: Pomi-T ›
Zyflamend, a blend of rosemary, turmeric, ginger, holy basil, green tea, hu zhang, Chinese goldthread, barberry, oregano, and baikal skullcap: Zyflamend ›

Keep reading about green tea or EGCG

See all our reviews of complementary therapies

Author

Nancy Hepp, MS

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Reviewer

Andrew Jackson, ND

Research Associate

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Last update: March 25, 2024

Last full literature review: January 2024

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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References[+]

References
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Green Tea or EGCG

How can green tea or EGCG help you? What the research says

Improving treatment outcomes

Optimizing your body terrain

Managing side effects and promoting wellness

Reducing cancer risk

Keep reading about green tea or EGCG

Author

Nancy Hepp, MS

Reviewer

Andrew Jackson, ND

Learn more

Optimizing Your Body Terrain

Understanding Research Studies

Turmeric and Curcumin