Green Tea

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Green Tea

Common Names

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

For Patients & Caregivers

Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.


What is it?

Green tea is a drink made from the Camellia sinensis plant. Fresh leaves are cut from this plant and steamed to make the tea.

You can drink green tea or take it orally (by mouth) in a pill or tablet as a dietary supplement. You can also use green tea extract on your skin as a cream.

What is it used for?

Green tea is used to:

  • Lower cholesterol levels
  • Prevent heart disease
  • Help treat high blood pressure
  • Prevent tooth decay
  • Treat warts on your genitals or anus

 Green tea also has other uses that haven’t been studied by doctors to see if they work.

It’s generally safe to drink green tea and use it in food. However, talk with your healthcare providers before taking supplements or higher amounts of green tea. Herbal supplements are stronger than the herbs you would use in cooking.

Supplements can also interact with some medications and affect how they work. For more information, read the “What else do I need to know?” section below.

What are the side effects?

Side effects of taking green tea supplements may include:

  • Nausea (feeling like you’re going to throw up)
  • Stomach pain
  • Drinking too much green tea can disrupt your sleep, and can also give you headaches
What else do I need to know?
  • Talk to your doctor if you’re taking iron supplements. Green tea can affect the way iron is absorbed in the body. 
  • Don’t drink green tea if you’re pregnant or breastfeeding. Green tea has caffeine in it that may cause your baby to have trouble sleeping.
  • Avoid drinking green tea if you have a stomach ulcer (sore in the lining of your stomach). Green tea may make your ulcer worse.
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For Healthcare Professionals

Scientific Name
Camellia sinensis
Clinical Summary

Green tea is a beverage derived from the unfermented leaves of a plant native to Asia. The extract is marketed as a dietary supplement to regulate blood sugar, cholesterol, blood pressure, and for weight loss and cancer prevention. Active constituents include the polyphenol epigallocatechin-3-gallate (EGCG), caffeine, and theanine. Green tea consumption may reduce the risk of hypertension (9) and cardiovascular disease (14), and a theaflavin-enriched extract lowered low-density lipoprotein cholesterol (LDL-C) levels (8). Green tea intake has also been associated with a reduction in self-reported depression (77). Some findings suggest that green tea can enhance glucose tolerance in healthy individuals (11) (12), and reduce fasting blood glucose levels (78). Data from studies on obese (10) (60) and diabetic patients (13) are mixed. But a green tea extract was shown useful, as an adjunct to the standard therapy, to improve arterial stiffness in patients with type-2 diabetes (80).

Topical application of green tea extracts was found effective against external genital and perianal warts (15) (16) (17). One such extract, sinecatechin, is an FDA-approved drug indicated for this use. Green tea extracts were also found beneficial for the treatment of acne  (83).

Investigations into the anticancer potential of green tea and its active compounds showed preventive benefits with green tea extracts among patients with oral premalignant lesions (41), or at high-risk of developing liver (61) or colorectal cancers (64). Another extract produced beneficial biologic responses in patients with chronic lymphocytic leukemia (52).

EGCG, applied topically, was reported to help relieve radiation-induced dermatitis in breast cancer patients (74) (75). In addition, oral EGCG consumption was found effective against acute radiation-induced esophagitis in lung cancer patients (76). However, an EGCG-enriched green tea was not useful as maintenance intervention in women with advanced stage ovarian cancer after standard treatment (71), and EGCG supplementation did not reduce likelihood of prostate cancer (63).

In studies of prostate cancer, supplementation with a blend of green tea, pomegranate, broccoli, and curcumin had a protective effect in patients following post-radical treatment (59). Green tea consumption also decreased PSA levels in patients prior to prostatectomy (72). However, higher doses of green tea catechins were associated with elevated incidence of prostate cancer in men with high grade prostatic intraepithelial neoplasia and/or atypical small acinar proliferation (73).

Furthermore, green tea extract combined with curcumin may be beneficial in the treatment of oral potentially malignant disorders (84). Data on whether green tea can reduce the risk of gastric and esophageal cancers are mixed (5) (6) (42). It was also not associated with risk of developing malignant lymphoma or multiple myeloma (65), although data suggest tea intake may reduce the risk of myelodysplastic syndrome (56). Other findings suggest that consumption may actually increase breast cancer risk in postmenopausal women (62). Future studies are needed to resolve this ambiguity and to determine potential beneficial effects of green tea consumption on overall cancer risk (81).

Moderate consumption of green tea was not associated with increased risk of kidney stone formation (85). But the caffeinated form may cause insomnia and nausea. Therefore, use of decaffeinated products may be preferred due to lower incidence of adverse events, but data are inconsistent regarding the relative efficacy of caffeinated versus decaffeinated teas. Animal studies indicate that oral consumption of green tea extract during fasting can increase the risk of toxicity (49). In humans, EGCG intake (200 mg, twice daily for one year) was shown to be safe (70) based on clinical data, whereas a daily dose amounting to 800 mg EGCG was associated with elevated liver enzymes, which was reversible with cessation of consumption (67). It is important to distinguish food from concentrated supplements because the dosage varies considerably, and that in turn can either confer benefits or cause harmful effects.

Purported Uses
  • Cancer prevention
  • Cancer treatment
  • Cardiovascular disease
  • Cognitive improvement
  • GI disorders
  • Hypertension
  • Weight loss
Mechanism of Action

Green tea is thought to confer cardiovascular protection by increasing HDL cholesterol and lowering LDL cholesterol and triglycerides (8) (29), as well as by blocking platelet aggregation. The tannins may have antibacterial properties (28) and can produce antidiarrheal effects. The flavonoid constituents may reduce lipoprotein oxidation (30).

Modulation of blood pressure by green tea is thought to be mediated through EGCG. It induces nitric oxide (NO) production via activation of endothelial NO synthase, resulting in vasodilation (27). In healthy subjects, a green tea extract modulated effective brain connectivity during working memory processing (55). EGCG inhibited aggregation of tau protein, thereby reducing toxicity in neuronal model cells (57).

Anticancer activities have been related to polyphenol content, with chemopreventive properties attributed to EGCG via apoptotic induction and tumor antiangiogenesis (20). EGCG may inhibit enzymes involved in cell replication and DNA synthesis by interfering with cell-to-cell adhesion or intracellular communication pathways required for cell division (21). In vitro data indicate that concentrations of 30 mcg/mL EGCG and (-)-epigallocatechin (EGC) inhibit lipoxygenase-dependent arachidonic acid metabolism by 30-75% in normal human colon mucosa and colon cancers (22). Other studies in human colon cancer cell lines suggest that EGCG inhibits topoisomerase I, but not topoisomerase II (23). It also inhibited DNA replication in leukemia cancer cell lines (24), and modulated vascular endothelial growth factor (VEGF) leading to apoptosis in leukemic cells (7).

Administration of green tea inhibits UVB light-induced carcinogenesis; when given before and during carcinogen treatment, it reduced incidence and number of stomach and esophageal tumors in mice (25).

Warnings
  • Although the U.S. Food and Drug Administration (FDA) includes tea on their list of “Generally Recognized As Safe” substances, pregnant women and women who breastfeed should limit their intake because of caffeine content.
  • Because tea can pass into breast milk, it may cause sleep disorders in nursing infants. Ingestion by infants has been linked to impaired iron metabolism and microcystic anemia.
  • Individuals with peptic ulcers should avoid drinking because it can stimulate the production of gastric acid (29).
  • The United States Pharmacopeia included this cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph: “Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes)” (86).
Adverse Reactions
  • Green tea is generally considered safe, but because of the caffeine content, excessive consumption can disrupt sleep and cause headaches. A few cases of hepatotoxicity have also been associated with green tea extracts containing high EGCG levels (44) (46) (47) (58).
  • Adverse reactions appear to be dose dependent. Clinical trials reported the following effects:
    — Nausea, abdominal pain, and transaminitis after intake of high dose EGCG (2000 mg orally twice per day) in patients with early stage chronic lymphocytic leukemia (52)
    — Elevation in alanine aminotransferase (ALT) levels, also after consumption of high amounts of EGCG (843 mg daily for one year) by postmenopausal women at risk for breast cancer (68)
    — In another study of EGCG in breast cancer patients, rectal bleeding (with 800mg daily), weight gain, indigestion and insomnia (daily dose of 1200 mg), and liver function abnormality (at 1,600 mg daily) were reported (69).
    However, in a study of men with high-grade prostatic intraepithelial neoplasia (HGPIN) and/or atypical small acinar proliferation (ASAP), EGCG (200 mg, twice daily for one year) was shown to be safe (70).
  • Pruritic swelling and darkening of lower lip following green tea consumption for several years (45) and thrombotic thrombocytopenic purpura after taking a green tea supplement for weight loss (48) have also been reported.
  • When consumed during fasting, green tea extract increased the risk of toxicity in animal studies. Whether it has the same effect in humans is not known (49).
Herb-Drug Interactions
  • Adenosine: The caffeine content may inhibit the hemodynamic effects of adenosine (18).
  • Anticoagulants / Antiplatelets: Theoretically, consumption of large amounts (.5-1 gallon/day) may provide enough vitamin K to antagonize the effects of anticoagulants and antiplatelet agents, though this effect has not been reported in humans (29) (34).
  • Atropine: The tannin content may reduce the absorption of atropine.
  • Iron supplements: The tannin content in may reduce the bioavailability of iron. Green tea should be taken either 2 hours before or 4 hours following iron administration.
  • Codeine: The tannin content may reduce the absorption of codeine (18).
  • Bortezomib: EGCG and other polyphenols can inhibit the therapeutic effect of bortezomib and other boronic acid based proteasome inhibitors (37).
  • Tamoxifen: EGCG was shown to increase the oral bioavailability of tamoxifen, increasing the potential for their interactions (38).
  • Verapamil: The bioavailability of verapamil increased significantly in the presence of EGCG, thought to be due to P-glycoprotein inhibition by EGCG (39).
  • Irinotecan: A study found EGCG to inhibit transport of irinotecan and its metabolite SN-38 into biliary elimination, resulting in their prolonged half-life which can increase toxicity (40).
  • Cytochrome P450 3A4 substrates: Green tea extract inhibits CYP 3A4 enzyme and can affect the intracellular concentration of drugs metabolized by this enzyme (43)(44) (87).
  • UGT (Uridine 5’-diphospho-glucuronosyltransferase) substrates: Green tea modulates UGT enzymes in vitro and can increase the side effects of drugs metabolized by them (51).
  • Acetaminophen: Green tea was shown to increase acetaminophen-induced hepatotoxicity in mice when administered following acetaminophen  (53).
  • Nadolol: Green tea extract inhibits OATP1A2 transporter and can reduce the absorption and plasma concentration of substrate drugs, like nadolol (54).
  • Palbociclib: The bioavailability of Palbociclib decreased following administration of green tea extract in a murine model (79). Clinical relevance has yet to be determined.
  • Ticagrelor: Green tea polyphenols were reported to inhibit the metabolism of ticagrelor, in vitro. Clinical relevance has yet to be determined (82).
  • Atorvastatin: Green tea limited hepatic drug uptake and increased plasma exposure to atorvastatin in a murine model. Clinical significance is not known (88).
  • Ziprasidone: A 23-year-old man who was stable for several months on this medication became psychotic within days following use of a green tea extract for weight loss. His symptoms resolved after eliminating green tea  (89)
Herb Lab Interactions
  • Caffeine in green tea may increase PT / PTT
Dosage (OneMSK Only)
References
  1. Hsu SD, et al. Chemoprevention of oral cancer by green tea. Gen Dent 2002;50:140-6.
  2. Pisters KM, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol 2001;19:1830-8.
  3. Proniuk S, et al. Preformulation study of epigallocatechin gallate, a promising antioxidant for topical skin cancer prevention. J Pharm Sci 2002;91:111-6.
  4. Sartippour MR, et al. Green tea inhibits vascular endothelial growth factor (VEGF) induction in human breast cancer cells. J Nutr 2002;132:2307-11.
  5. Sun CL, et al. Urinary tea polyphenols in relation to gastric and esophageal cancers: a prospective study of men in Shanghai, China. Carcinogenesis 2002;23:1497-503.
  6. Nechuta S, Shu XO, Li HL, et al. Prospective cohort study of tea consumption and risk of digestive system cancers: results from the Shanghai Women’s Health Study. Am J Clin Nutr. 2012 Nov;96(5):1056-63. doi: 10.3945/ajcn.111.031419. Epub 2012 Oct 10.
  7. Lee YK, et al. VEGF Receptor Phosphorylation Status and Apoptosis is Modulated by a Green Tea Component, Epigallocatechin-3-gallate (EGCG) in B cell Chronic Lymphocytic Leukemia. Blood 2004;104(3):788-94.
  8. Maron DJ, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med. 2003 Jun 23;163(12):1448-53.
  9. Yang YC, et al.The protective effect of habitual tea consumption on hypertension. Arch Intern Med. 2004 Jul 26;164(14):1534-40.
  10. Brown AL, Lane J, Coverly J, et al. Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial. Br J Nutr. Aug 19 2008:1-9.
  11. Tsuneki H, Ishizuka M, Terasawa M, Wu JB, Sasaoka T, Kimura I. Effect of green tea on blood glucose levels and serum proteomic patterns in diabetic (db/db) mice and on glucose metabolism in healthy humans.BMC Pharmacol. Aug 26 2004;4:18.
  12. Venables MC, Hulston CJ, Cox HR, Jeukendrup AE. Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. Am J Clin Nutr. Mar 2008;87(3):778-784.
  13. Mackenzie T, Leary L, Brooks WB. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Metabolism. Oct 2007;56(10):1340-1344.
  14. Kuriyama S, Shimazu T, Ohmori K, et al. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. JAMA. 2006;296(10):1255-65.
  15. Gross G, Meyer KG, Pres H, Thielert C, Tawfik H, Mescheder A. A randomized, double-blind, four-arm parallel-group, placebo-controlled Phase II/III study to investigate the clinical efficacy of two galenic formulations of Polyphenon E in the treatment of external genital warts.J Eur Acad Dermatol Venereol. Nov 2007;21(10):1404-1412.
  16. Stockfleth E, Beti H, Orasan R, et al. Topical Polyphenon E in the treatment of external genital and perianal warts: a randomized controlled trial.Br J Dermatol. Jun 2008;158(6):1329-1338.
  17. Tatti S, Swinehart JM, Thielert C, Tawfik H, Mescheder A, Beutner KR. Sinecatechins, a defined green tea extract, in the treatment of external anogenital warts: a randomized controlled trial. Obstet Gynecol. Jun 2008;111(6):1371-1379.
  18. Brinker F. Herb Contraindications and Drug Interactions, 3rd ed. Sandy (OR): Eclectic Medical Publications; 2001.
  19. Yang CS, et al. Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers. Cancer Epidemiol Biomarkers Prev 1998;7:351-4.
  20. Tosetti F, Ferrari N, De Flora S. Angioprevention: angiogenesis is a common and key target for cancer chemopreventive agents. FASEB J 2002;16:2-14.
  21. Yang CS, et al. Prevention of carcinogenesis by tea polyphenols. Drug Metab Rev 2001;33:237-53.
  22. Hong J, et al. Effects of purified green and black tea polyphenols on cyclooxygenase- and lipoxygenase-dependent metabolism of arachidonic acid in human colon mucosa and colon tumor tissues. Biochem Pharmacol 2001;62:1175-83.
  23. Berger SJ, et al. Green tea constituent (—)-epigallocatechin-3-gallate inhibits topoisomerase I activity in human colon carcinoma cells. Biochem Biophys Res Commun 2001;288:101-5.
  24. Smith DM, et al. Green tea polyphenol epigallocatechin inhibits DNA replication and consequently induces leukemia cell apoptosis. Int J Mol Med 2001;7:645-52.
  25. Huang MT, et al. Effects of tea, decaffeinated tea, and caffeine on UVB light-induced complete carcinogenesis in SKH-1 mice: demonstration of caffeine as a biologically important constituent of tea. Cancer Res 1997;57:2623-9.
  26. Yang CS, et al. Human salivary tea catechin levels and catechin esterase activities: implications in human cancer prevention studies. Cancer Epidemiol Biomarkers Prev 1999;8:83-9.
  27. Lorenz M, Wessler S, Follmann E, et al. A constituent of green tea, epigallocatechin-3-gallate, activates endothelial nitric oxide synthase by a phosphatidylinositol-3-OH-kinase-, cAMP-dependent protein kinase-, and Akt-dependent pathway and leads to endothelial-dependent vasorelaxation. J Biol Chem. Feb 13 2004;279(7):6190-6195.
  28. Hamilton-Miller JM. Anti-cariogenic properties of tea (Camellia sinensis). J Med Microbiol 2001;50:299-302.
  29. LaValle JB, et al. IN: Natural Therapeutics Pocket Guide 2000-2001;452-4.
  30. Dulloo AG, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70:1040-5.
  31. van het Hof KH, et al. Bioavailability of catechins from tea: the effect of milk. Eur J Clin Nutr 1998;52:356-9.
  32. Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334-50.
  33. He YH, Kies C. Green and black tea consumption by humans: impact on polyphenol concentrations in feces, blood, and urine. Plant Foods Hum Nutr 1994;46:221-9.
  34. Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother 1999;33:426-8.
  35. Tsubono Y, et al. Green tea and the risk of gastric cancer in Japan. N Engl J Med 2001;344:632-6
  36. Li Q, Kakizaki M, Kuriyama S, et al. Green tea consumption and lung cancer risk: the Ohsaki study. Br J Cancer 2008 Oct 7;99(7):1179-84.
  37. Goldin EB, Lam P, Kardosh A, et al. Green tea polyphenols block the anticancer effects of bortezomib and other boronic acid based proteasome inhibitors. Blood 2009 Jun 4;113(23):5927-37.
  38. Shin SC, Choi JS. Effects of epigallocatechin gallate on the oral bioavailability and pharmacokinetics of tamoxifen and its main metabolite, 4-hydroxytamoxifen, in rats. Anticancer Drugs. 2009 Aug;20(7):584-8.
  39. Chung JH, Choi DH, Choi JS. Effects of oral epigallocatechin gallate on the oral pharmacokinetics of verapamil in rats. Biopharm Drug Dispos. 2009 Mar;30(2):90-3.
  40. Lin LC, Wang MN, Tsai TH. Food-drug interaction of (-)-epigallocatechin-3-gallate on the pharmacokinetics of irinotecan and the metabolite SN-38. Chem Biol Interact. 2008 Aug 11;174(3):177-82.
  41. Tsao AS, Liu D, Martin J, et al. Phase II randomized, placebo-controlled trial of green tea extract in patients with high-risk oral premalignant lesions. Cancer Prev Res (Phila Pa). 2009 Nov;2(11):931-41.
  42. Myung SK, Bae WK, Oh SM, et al. Green tea consumption and risk of stomach cancer: a meta-analysis of epidemiologic studies. Int J Cancer. 2009 Feb 1;124(3):670-7.
  43. Wanwimolruk S, Wong K, Wanwimolruk P. Variable inhibitory effect of different brands of commercial herbal supplements on human cytochrome P-450 CYP3A4. Drug Metabol Drug Interact. 2009;24(1):17-35.
  44. Mazzanti G, Menniti-Ippolito F, Moro PA, et al. Hepatotoxicity from green tea: a review of the literature and two unpublished cases. Eur J Clin Pharmacol. 2009 Apr;65(4):331-41.
  45. Lee JI, Cho BK, Ock SM, Park HJ. Pigmented contact cheilitis: from green tea? Contact Dermatitis. 2010 Jan;62(1):60-1.
  46. Vanstraelen S, Rahier J, Geubel AP. Jaundice as a misadventure of a green tea (camellia sinensis) lover : a case report. Acta Gastroenterol Belg. 2008 Oct-Dec;71(4):409-12.
  47. Verhelst X, Burvenich P, Van Sassenbroeck D, Gabriel C, Lootens M, Baert D. Acute hepatitis after treatment for hair loss with oral green tea extracts (Camellia Sinensis). Acta Gastroenterol Belg. 2009 Apr-Jun;72(2):262-4.
  48. Liatsos GD, Moulakakis A, Ketikoglou I, Klonari S. Possible green tea-induced thrombotic thrombocytopenic purpura. Am J Health Syst Pharm. 2010 Apr 1;67(7):531-4.
  49. Wu KM. Green Tea Extract Induced Lethal Toxicity in Fasted but Not in Nonfasted Dogs. Int J Toxicol. 2011 Feb;30(1):19-20.
  50. Engdal S, Nilsen OG. In vitro inhibition of CYP3A4 by herbal remedies frequently used by cancer patients. Phytother Res. 2009 Jul;23(7):906-12.
  51. Mohamed ME, Frye RF. Effects of herbal supplements on drug glucuronidation. Review of clinical, animal, and in vitro studies. Planta Med. 2011 Mar;77(4):311-21.
  52. Shanafelt TD, Call TG, Zent CS, et al. Phase 2 trial of daily, oral polyphenon E in patients with asymptomatic, Rai stage 0 to II chronic lymphocytic leukemia. Cancer. 2012 Jul 3. doi: 10.1002/cncr.27719. [Epub ahead of print]
  53. Salminen WF, Yang X, Shi Q, Greenhaw J, Davis K, Ali AA. Green tea extract can potentiate acetaminophen-induced hepatotoxicity in mice. Food Chem Toxicol. 2012 May;50(5):1439-46.
  54. S Misaka, J Yatabe, F Müller, et al. Green tea ingestion greatly reduces plasma concentrations of nadolol in healthy subjects. Clin Pharmacol Ther. 2014 Apr;95(4):432-8.
  55. Schmidt A, Hammann F, Wölnerhanssen B, et al. Green tea extract enhances parieto-frontal connectivity during working memory processing. Psychopharmacology (Berl). 2014 Oct;231(19):3879-88.
  56. Liu P, Zhang M, Jin J, Holman CD. Tea consumption reduces the risk of de novo myelodysplastic syndromes. Leuk Res. 2015 Feb;39(2):164-9.
  57. Wobst HJ, Sharma A, Diamond MI, Wanker EE, Bieschke J. The green tea polyphenol (-)-epigallocatechin gallate prevents the aggregation of tau protein into toxic oligomers at substoichiometric ratios. FEBS Lett. 2015 Jan 2;589(1):77-83.
  58. Fernández J, Navascués C, Albines G, Franco L, Pipa M, Rodríguez M. Three cases of liver toxicity with a dietary supplement intended to stop hair loss. Rev Esp Enferm Dig.2014 Dec;106(8):552-5.
  59. Thomas R, Williams M, Sharma H, Chaudry A, Bellamy P. A double-blind, placebo-controlled randomised trial evaluating the effect of a polyphenol-rich whole food supplement on PSA progression in men with prostate cancer—the U.K. NCRN Pomi-T study. Prostate Cancer Prostatic Dis. 2014 Jun;17(2):180-6.
  60. Dostal AM, Arikawa A, Espejo L, et al. Long-term supplementation of green tea extract does not modify adiposity or bone mineral density in a randomized trial of overweight and obese postmenopausal women. J Nutr. Dec 23 2015.
  61. Xue KS, Tang L, Cai Q, et al. Mitigation of fumonisin biomarkers by green tea polyphenols in a high-risk population of hepatocellular carcinoma. Sci Rep. 2015;5:17545.
  62. Li M, Tse LA, Chan WC, Kwok CH, et al. Evaluation of breast cancer risk associated with tea consumption by menopausal and estrogen receptor status among Chinese women in Hong Kong.Cancer Epidemiol. 2015 Dec 8;40:73-78.
  63. Kumar NB, Pow-Sang J, Egan KM, et al. Randomized, Placebo-Controlled Trial of Green Tea Catechins for Prostate Cancer Prevention. Cancer Prev Res (Phila).2015 Oct;8(10):879-87.
  64. Shin CM, Lee DH, Seo AY, 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. Clin Nutr. 2017 Jan 29. pii: S0261-5614(17)30038-9.
  65. Ugai T, Matsuo K, Sawada N, Iwasaki M, Yamaji T, Shimazu T, Sasazuki S, Inoue M, Kanda Y, Tsugane S; Japan Public Health Center-based Prospective Study Group. Coffee and Green Tea Consumption and Subsequent Risk of Malignant Lymphoma and Multiple Myeloma in Japan: The Japan Public Health Center-based Prospective Study. Cancer Epidemiol Biomarkers Prev. 2017 Aug;26(8):1352-1356.
  66. Dekant W, Fujii K, Shibata E, Morita O, Shimotoyodome A. Safety assessment of green tea based beverages and dried green tea extracts as nutritional supplements. Toxicol Lett. 2017 Aug 5;277:104-108.
  67. Yu Z, Samavat H, Dostal A, et al. Effect of Green Tea Supplements on Liver Enzyme Elevation: Results from a Randomized Intervention Study in the United States. Cancer Prev Res (Phila). 2017 Aug 1. pii: canprevres.0160.2017. doi: 10.1158/1940-6207.CAPR-17-0160. [Epub ahead of print]
  68. Dostal AM, Samavat H, Bedell S, et al. The safety of green tea extract supplementation in postmenopausal women at risk for breast cancer: results of the Minnesota Green Tea Trial. Food Chem Toxicol. 2015 Sep;83:26-35.
  69. Crew KD, Ho KA, Brown P, 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. J Hum Nutr Diet. 2015 Jun;28(3):272-82.
  70. Kumar NB, Pow-Sang J, Spiess PE, et al. Randomized, placebo-controlled trial evaluating the safety of one-year administration of green tea catechins. Oncotarget. 2016 Oct 25;7(43):70794-70802.
  71. Trudel D, Labbé DP, Araya-Farias M, 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. Gynecol Oncol. 2013 Nov;131(2):357-61.
  72. Henning SM, Wang P, Said JW, 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.
  73. Gontero P, Marra G, Soria F, et al. A randomized double-blind placebo controlled phase I-II study on clinical and molecular effects of dietary supplements in men with precancerous prostatic lesions. Chemoprevention or “chemopromotion”? Prostate. 2015 Aug 1;75(11):1177-86.
  74. Zhu W, Jia L, Chen G, et al. Epigallocatechin-3-gallate ameliorates radiation-induced acute skin damage in breast cancer patients undergoing adjuvant radiotherapy. Oncotarget. 2016 Jul 26;7(30):48607-48613.
  75. Zhao H, Zhu W, Jia L, et al. Phase I study of topical epigallocatechin-3-gallate (EGCG) in patients with breast cancer receiving adjuvant radiotherapy. Br J Radiol. 2016;89(1058):20150665.
  76. Zhao H, Xie P, Li X, et al. A prospective phase II trial of EGCG in treatment of acute radiation-induced esophagitis for stage III lung cancer. Radiother Oncol. 2015 Mar;114(3):351-6.
  77. Kim J, Kim J. Green Tea, Coffee, and Caffeine Consumption Are Inversely Associated with Self-Report Lifetime Depression in the Korean Population. Nutrients. 2018 Sep 1;10(9). pii: E1201.
  78. Kondo Y, Goto A, Noma H, Iso H, Hayashi K, Noda M. Effects of Coffee and Tea Consumption on Glucose Metabolism: A Systematic Review and Network Meta-Analysis. Nutrients. 2018 Dec 27;11(1). pii: E48.
  79. Paul D, Surendran S, Chandrakala P, Satheeshkumar N. An assessment of the impact of green tea extract on palbociclib pharmacokinetics using a validated UHPLC-QTOF-MS method. Biomed Chromatogr. 2018 Dec 13:e4469.
  80. Quezada-Fernández P, Trujillo-Quiros J, Pascoe-González S, et al. Effect of green tea extract on arterial stiffness, lipid profile and sRAGE in patients with type 2 diabetes mellitus: a randomised, double-blind, placebo-controlled trial. Int J Food Sci Nutr. 2019 Dec;70(8):977-985.
  81. Filippini T, Malavolti M, Borrelli F, et al. Green tea (Camellia sinensis) for the prevention of cancer. Cochrane Database Syst Rev. 2020 Mar 2;3:CD005004.
  82. Wang ZT, Xue Y, Sun H, et al. Effect of tea polyphenols on the oral and intravenous pharmacokinetics of ticagrelor in rats and its in vitro metabolism. J Food Sci. 2020 Apr;85(4):1285-1291.
  83. Kim S, Park TH, Kim WI, Park S, Kim JH, Cho MK. The effects of green tea on acne vulgaris: A systematic review and meta-analysis of randomized clinical trials. Phytother Res. 2021 Jan;35(1):374-383.
  84. Neetha 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. J Contemp Dent Pract. 2020 May 1;21(5):521-531. 
  85. Barghouthy Y, Corrales M, Doizi S, Somani BK, Traxer O. Tea and coffee consumption and the risk of urinary stones-a systematic review of the epidemiological data. World J Urol. 2021 Jan 17.
  86. Oketch-Rabah HA, Roe AL, Rider CV, et al. United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts. Toxicol Rep. 2020 Feb 15;7:386-402.
  87. Darweesh RS, El-Elimat T, Zayed A, et al. The effect of grape seed and green tea extracts on the pharmacokinetics of imatinib and its main metabolite, N-desmethyl imatinib, in rats. BMC Pharmacol Toxicol. 2020 Nov 16;21(1):77.
  88. Yao HT, Hsu YR, Li ML. Beverage-Drug Interaction: Effects of Green Tea Beverage Consumption on Atorvastatin Metabolism and Membrane Transporters in the Small Intestine and Liver of Rats. Membranes (Basel). 2020 Sep 14;10(9):233.
  89. Mahgoub Y, Madden K, Xia T. When Green Becomes Mean: Green Tea Extract Reduces Ziprasidone’s Effect and Causes Psychosis. Prim Care Companion CNS Disord. 2020 Jan 23;22(1):19l02487.
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