Green Tea

Supplement Forms/Alternate Names:

Camellia sinensis

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

Unlikely to Be Effective

  • Gout —unlikely to reduce the risk L1

Not Enough Data to Assess

  • Diabetic retinopathy H1
  • Gastric cancer K1
  • Polycystic ovary syndrome V1

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

A. Bladder Cancer

A1. 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.

B. Breast Cancer

B1. 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.

B2. 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.

C. Cardiovascular Disease

C1. Hartley L, Flowers N, et al. Green and black tea for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2013;(6):CD009934.

C2. 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.

D. Cognitive Disorders

D1. 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.

E. Colorectal Cancer

E1. 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.

E2. 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.

E3. Chen Y, Wu Y, et al. An inverse association between tea consumption and colorectal cancer risk. Oncotarget. 2017 Jun 6;8(23):37367-37376.

F. Coronary Artery Disease

F1. 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.

G. Diabetes

G1. 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.

G2. 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.

G3. 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.

H. Diabetic Retinopathy

H1. Dow C, Mancini F, et al. Diet and risk of diabetic retinopathy: a systematic review. Eur J Epidemiol. 2018 Feb;33(2):141-156.

I. Esophageal Cancer

I1. 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.

I2. 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.

J. External Anogenital Warts

J1. 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.

K. Gastric Cancer

K1. 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.

L. Gout

L1. 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.

M. High Blood Pressure

M1. 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.

M2. 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.

M3. 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.

M4. 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.

N. High Cholesterol

N1. 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.

N2. 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.

N3. 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.

O. Inflammatory Bowel Disease

O1. 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.

P. Liver Cancer

P1. 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.

P2. 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.

Q. Lung Cancer

Q1. 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.

R. Nonalcoholic Fatty Liver Disease

R1. 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.

S. Obesity

S1. 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.

S2. 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.

S3. 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.

T. Oral Cancer

T1. 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.

U. Oral Hygiene

U1. 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.

V. Polycystic Ovary Syndrome

V1. 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.

W. Prostate Cancer

W1. 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.

W2. 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.

X. Safety

X1. Izzo AA. Interactions between herbs and conventional drugs: overview of the clinical data. Med Princ Pract. 2012;21(5):404-428.

X2. Asher GN, Corbett AH, et al. Common Herbal Dietary Supplement-Drug Interactions. Am Fam Physician. 2017 Jul 15;96(2):101-107.

X3. 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.

Last reviewed March 2020 by EBSCO NAT Review Board Eric Hurwitz, DC  Last Updated: 6/22/2020