Introduction
Green tea is a bitter tea made from the leaves of a small shrub. Green tea has been used to lower cholesterol, blood pressure, and body mass index (BMI). Green tea is steeped and can be made into a hot or cold beverage. It can also be taken as a pill, powder, or extract.
Dosages
3 cups daily
What Research Shows
Likely Effective
- Bladder cancer —likely to lower the risk in Asian people A1
- Cardiovascular disease —likely to lower risk C1, C2
- Cognitive disorders—likely to lower risk D1
- Colorectal cancer —likely to lower risk E1-E3
- Diabetes —likely to lower blood glucose levels and improve insulin sensitivity G1-G3
- Esophageal cancer —likely to lower risk I1, I2
- External anogenital warts—likely to prevent recurrence when used as an ointment J1
- High blood pressure —likely to lower blood pressure M1-M4
- High cholesterol —likely to lower total and LDL (“bad”) cholesterol N1-N3
- Liver cancer —likely to lower risk P1, P2
- Lung cancer —likely to lower risk Q1
- Nonalcoholic fatty liver disease —likely to lower BMI, total cholesterol, and LDL (“bad”) cholesterol R1
- Obesity —likely to lower LDL (“bad”) cholesterol and modestly improve weight loss S1-S3
- Oral cancer —likely to lower the risk T1
- Prostate cancer —likely to lower risk W1, W2
May Be Effective
- Breast cancer —may lower risk B1, B2
- Coronary artery disease —may lower risk F1
- Inflammatory bowel disease —may ease symptoms O1
- Oral hygiene —may ease plaque and inflammation when used as a mouthwash U1
Not Enough Data to Assess
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Safety Notes
It is likely safe for most adults to drink green tea in small doses for a short time. Women who are pregnant or breastfeeding should limit their intake of green tea. Not enough studies have been done to say whether it is safe to use for a long period. X1-X3
Interactions
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.
References
REFA Bladder Cancer
REFA1 Wang X, Lin YW, et al. A meta-analysis of tea consumption and the risk of bladder cancer. Urol Int. 2013;90(1):10-16.
REFB Breast Cancer
REFB1 Gianfredi 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). pii: E1886.
REFB2 Yu 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):e16147.
REFC Cardiovascular Disease
REFC1 Hartley L, Flowers N, et al. Green and black tea for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2013;(6):CD009934.
REFC2 Pang J, Zhang Z, et al. Green tea consumption and risk of cardiovascular and ischemic related diseases: A meta-analysis. Int J Cardiol. 2016;202:967-974.
REFD Cognitive Disorders
REFD1 Liu X, Du X, et al. Association between tea consumption and risk of cognitive disorders: A dose-response meta-analysis of observational studies. Oncotarget. 2017 Jun 27;8(26):43306-43321.
REFE Colorectal Cancer
REFE1 Wang XJ, Zeng XT, et al. Association between green tea and colorectal cancer risk: a meta-analysis of 13 case-control studies. Asian Pac J Cancer Prev. 2012;13(7):3123-3127.
REFE2 Wang ZH, Gao QY, et al. Green tea and incidence of colorectal cancer: evidence from prospective cohort studies. Nutr Cancer. 2012;64(8):1143-1152.
REFE3 Chen Y, Wu Y, et al. An inverse association between tea consumption and colorectal cancer risk. Oncotarget. 2017 Jun 6;8(23):37367-37376.
REFF Coronary Artery Disease
REFF1 Wang ZM, Zhou B, et al. Black and green tea consumption and the risk of coronary artery disease: a meta-analysis. Am J Clin Nutr. 2011 Mar;93(3):506-515.
REFG Diabetes
REFG1 Liu K, Zhou R, et al. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. Am J Clin Nutr. 2013;98(2):340-348.
REFG2 Yang WS, Wang WY, et al. Tea consumption and risk of type 2 diabetes: a dose-response meta-analysis of cohort studies. Br J Nutr. 2014 Apr 28;111(8):1329-1339.
REFG3 Wang X, Tian J, et al. Effects of green tea or green tea extract on insulin sensitivity and glycaemic control in populations at risk of type 2 diabetes mellitus: a systematic review and meta-analysis of randomised controlled trials. J Hum Nutr Diet. 2014 Oct;27(5):501-512.
REFH Diabetic Retinopathy
REFH1 Dow C, Mancini F, et al. Diet and risk of diabetic retinopathy: a systematic review. Eur J Epidemiol. 2018 Feb;33(2):141-156.
REFI Esophageal Cancer
REFI1 Sang LX, Chang B, et al. Green tea consumption and risk of esophageal cancer: a meta-analysis of published epidemiological studies. Nutr Cancer. 2013;65(6):802-812.
REFI2 Zheng 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. Nutr Cancer. 2013;65(1):1-16.
REFJ External Anogenital Warts
REFJ1 Tzellos TG, Sardeli C, et al. Efficacy, safety and tolerability of green tea catechins in the treatment of external anogenital warts: a systematic review and meta-analysis. J Eur Acad Dermatol Venereol. 2011 Mar;25(3):345-353.
REFK Gastric Cancer
REFK1 Huang 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 Nutr. 2017 Dec;20(17):3183-3192.
REFL Gout
REFL1 Zhang Y, Cui Y, et al. Is tea consumption associated with the serum uric acid level, hyperuricemia or the risk of gout? A systematic review and meta-analysis. BMC Musculoskelet Disord. 2017 Feb 28;18(1):95.
REFM High Blood Pressure
REFM1 Khalesi S, Sun J, et al. Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. Eur J Nutr. 2014 Sep;53(6):1299-311.
REFM2 Liu G, Mi XN, et al. Effects of tea intake on blood pressure: a meta-analysis of randomised controlled trials. Br J Nutr. 2014 Oct 14;112(7):1043-1054.
REFM3 Onakpoya I, Spencer E, et al. The effect of green tea on blood pressure and lipid profile: a systematic review and meta-analysis of randomized clinical trials. Nutr Metab Cardiovasc Dis. 2014;24(8):823-836.
REFM4 Peng X, Zhou R, et al. Effect of green tea consumption on blood pressure: a meta-analysis of 13 randomized controlled trials. Sci Rep. 2014;4:6251.
REFN High Cholesterol
REFN1 Zheng XX, Xu YL, et al. Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials. Am J Clin Nutr. 2011 Aug;94(2):601-610.
REFN2 Kim A, Chiu A, et al. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc. 2011;111(11):1720-1729.
REFN3 Khalesi S, Sun J, et al. Green tea catechins and blood pressure: a systematic review and meta-analysis of randomised controlled trials. Eur J Nutr. 2014 Sep;53(6):1299-311.
REFO Inflammatory Bowel Disease
REFO1 Rossi RE, Whyand T, et al. The role of dietary supplements in inflammatory bowel disease: a systematic review. Eur J Gastroenterol Hepatol. 2016 Dec;28(12):1357-1364.
REFP Liver Cancer
REFP1 Fon Sing M, Yang WS, et al. Epidemiological studies of the association between tea drinking and primary liver cancer: a meta-analysis. Eur J Cancer Prev. 2011 May;20(3):157-165.
REFP2 Ni CX, Gong H, et al. Green Tea Consumption and the Risk of Liver Cancer: A Meta-Analysis. Nutr Cancer. 2017 Feb-Mar;69(2):211-220.
REFQ Lung Cancer
REFQ1 Wang L, Zhang X, et al. Tea consumption and lung cancer risk: a meta-analysis of case-control and cohort studies. Nutrition. 2014 Oct;30(10):1122-1127.
REFR Nonalcoholic Fatty Liver Disease
REFR1 Mansour- Ghanaei F, Hadi A, et al. Green tea as a safe alternative approach for nonalcoholic fatty liver treatment: A systematic review and meta-analysis of clinical trials. Phytother Res. 2018;32(10):1876-1884.
REFS Obesity
REFS1 Hursel R, Viechtbauer W, et al. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obes (Lond). 2009 Sep;33(9):956-961.
REFS2 Jurgens TM, Whelan AM, et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev. 2012;12:CD008650.
REFS3 Yuan F, Dong H, et al. Effects of green tea on lipid metabolism in overweight or obese people: A meta-analysis of randomized controlled trials. Mol Nutr Food Res. 2018;62(1):10.
REFT Oral Cancer
REFT1 Wang W, Yang Y, et al. Association of tea consumption and the risk of oral cancer: a meta-analysis. Oral Oncol. 2014 Apr;50(4):276-281.
REFU Oral Hygiene
REFU1 Mathur A, Gopalakrishnan D, et al. Efficacy of green tea-based mouthwashes on dental plaque and gingival inflammation: A systematic review and meta-analysis. Indian J Dent Res. 2018 Mar-Apr;29(2):225-232.
REFV Polycystic Ovary Syndrome
REFV1 Arentz S, Smith CA, et al. Nutritional supplements and herbal medicines for women with polycystic ovary syndrome; a systematic review and meta-analysis. BMC Complement Altern Med. 2017 Nov 25;17(1):500.
REFW Prostate Cancer
REFW1 Jacob SA, Khan TM, et al. The Effect of Green Tea Consumption on Prostate Cancer Risk and Progression: A Systematic Review. Nutr Cancer. 2017 Apr;69(3):353-364.
REFW2 Guo 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.
REFX Safety
REFX1 Izzo AA. Interactions between herbs and conventional drugs: overview of the clinical data. Med Princ Pract. 2012;21(5):404-428.
REFX2 Asher GN, Corbett AH, et al. Common Herbal Dietary Supplement-Drug Interactions. Am Fam Physician. 2017 Jul 15;96(2):101-107.
REFX3 Hu J, Webster D, et al. The safety of green tea and green tea extract consumption in adults - Results of a systematic review. Regul Toxicol Pharmacol. 2018 Jun;95:412-433.