Also known as: Green Sencha Tea, Japanese Tea.

Scientific name: Camellia sinensis, it is from the exact same tea plant as Black tea commonly used throughout the world. 

Botanical family: Theaceae.

Parts used: Bud leaf and stem.

 

Traditional use.

Green tea has been consumed and enjoyed as a beverage for centuries. Green tea is produced by steaming fresh leaves at high temperature. Unlike black and oolong (partially fermented) teas, green tea is not fermented.

Improving cognitive performance and mental alertness is a traditional use for green tea. It is also used to treat stomach disorders, vomiting, diarrhea, and headaches. Green tea has a history of use for weight loss. It has a role in cancer prevention and treatment including breast cancer, cervical cancer, prostate cancer, colon cancer, gastric cancer, lung cancer, leukemia, and skin cancer related to ultraviolet radiation (e.g. sunburn) and other environmental causes. It has traditionally been used for its anti-viral effects on the wart virus including genital warts, perianal warts and cervical cell changes. Other uses include osteoporosis, Crohn's disease, Parkinson's disease, cardiovascular disease, diabetes, low blood pressure, chronic fatigue syndrome, tooth decay, kidney stones, and skin damage.

 

Topically, green tea is used as a wash to soothe sunburn, as a poultice for bags under the eyes, as a compress for headache or tired eyes, and to stop the bleeding of tooth sockets. Green tea in chewable candy is used for inflammation of the gums. Green tea is also used topically to prevent skin damage and cancer related to ultraviolet radiation (e.g. sunburn) and other environmental causes.

 

Safety.

There are no concerns about safety when consumed as a beverage in moderate amounts of 1-4 cups of green tea per day. ^{(1,2,3,4,5,6,7,8)}

Green tea extract as a supplement containing 7% caffeine has been used safely for six months. ⁽⁹⁾

Avoid using high doses long-term because Green tea contains a significant amount of caffeine. Typically a cup of green tea contains 35-60mgs of caffeine.

Children: While no safety concerns have been highlighted avoid caffeinated drinks in children and limit to 1 cup per day. ^(11,12) Avoid giving green tea to infants, as they have an increased risk of anemia. ⁽⁸⁸⁾

Pregnancy: There are no reported problems when used orally in moderate amounts of two cups per day.

Breastfeeding: There are no particular concerns when used orally in moderate amounts of 1-4 cups per day. If the baby has loose stools exclude green tea, black tea and coffee to see if caffeine is contributing to the problem.

Constituents.

 

Scientific Evidence.

Mental Alertness. Green tea and other caffeinated beverages prevent a decline in alertness and cognitive capacity when consumed throughout the day. ^(10,13,14)

 

Bladder cancer, esophageal cancer, and pancreatic cancer. cervical dysplasia. Drinking green tea is associated with a reduced the risk of bladder cancer, esophageal cancer, and pancreatic cancer. ^{(15,16,17,18,19)}

Green tea as an oral or topical preparation seems to reduce cervical dysplasia caused by human warts (papilloma virus) infection. ^(20).

 

High Cholesterol. Green tea taken orally lowers cholesterol and triglycerides.^(21)(22)

Low Blood Pressure. Consuming caffeinated beverages including Green Tea increases blood pressure in elderly people with low blood pressure after meals which may prevent falls. ^(23,24)

Oral leukoplakia (lesions of the mouth that may progress to cancer). Drinking green tea orally decreases the size of lesions in patients with oral leukoplakia. ⁽²⁵⁾

Ovarian cancer; Women who regularly consume green tea or black tea, have a lower risk of developing ovarian cancer.^{(92,25,26,27)}

Parkinson's disease. Consuming green tea orally helps prevent or delay the onset of Parkinson's disease. ^{(28, 29)}

Prevention of colorectal cancer.

Population studies suggest that consuming green tea does not have any effect on colon cancer risk. ^(30,31,32)

 

Breast cancer. Population studies suggest that green tea does not seem to reduce the risk of initially developing breast cancer in Asian populations; ^(33.34) however, in Asian-American populations some evidence suggests that drinking green tea might reduce the risk of developing breast cancer. ⁽³⁵⁾

Additional population research suggests that Asian women who have had early breast cancer (Stage 1-11) who drink 3-5 of more cups of green tea daily seem to have reduced risk of breast cancer recurrence. ^(36,33)

Cardiovascular disease. A large-scale population study in Japan suggests that consuming 3 or more cups of green tea daily significantly decreases the risk of cardiovascular and all-cause mortality compared to drinking less than one cup daily. ⁽³²⁾

Diabetes. Population studies suggests that Japanese adults who consume 6 or more cups/day of green tea have a 33% lower risk of developing type 2 diabetes.⁽³⁷⁾

Gastric Cancer. There is conflicting evidence about the effects of green tea on gastric cancer risk.

Gingivitis (inflammation of the gums); Green tea extract in chewable candy appears to reduce inflammation. ⁽³⁸⁾

High Blood Pressure. There is evidence of variable effects of green tea depending on the physiological state of the tissues when taken by individuals. Population studies in Chinese people show that drinking 120-599 mL of green tea or oolong tea daily is associated with a 46% lowered risk of developing hypertension compared with non-habitual tea drinkers. Drinking more than 600 mL per day is associated with a 65% reduced risk. ⁽³⁹⁾ However, clinical studies on people with normal and high blood pressure show that green tea or black tea has no effect on their blood pressure. ⁽⁴⁰⁾ This apparent contradiction is common with herbal medicines who only have an action when it is required to normalise the physiological terrain. It is one of the benefits of multi constituent medicines. Active constituents can vary from person to person depending on their individual physiology.

Lung Cancer. There is conflicting evidence about the effects of green tea on lung cancer risk. ^{(32) (41)}

Obesity. There is conflicting evidence about the effectiveness of green tea for obesity and weight loss. A meta-analysis of clinical studies suggests that, overall, taking green tea extract 576-714 mg/day along with caffeine seems to modestly reduce body mass index (BMI), body weight, and waist circumference compared to caffeine alone. But taking green tea extract without caffeine does not seem to significantly reduce weight or waist circumference. ^{(42) (43)}

Osteoporosis. Population research suggests that drinking green tea for ten years is associated with increased bone mineral density. ⁽⁴⁴⁾

Prostate cancer. Chinese men who consume green tea seem to have a lower risk of developing prostate cancer. ⁽⁴⁵⁾ Preliminary clinical research suggests that men with advanced cancer who take green tea supplements (containing catechins 200 mg three times daily) for a year seem to have a reduced risk of progression to prostate cancer. ⁽⁴⁶⁾

Osteoarthritis

 

Mechanism of action.

Polyphenols including flavanols, flavandiols, flavonoids, and phenolic acids are abundant in green tea. The flavanols are all referred to as catechins. These seem to be responsible for many of the proposed benefits of green tea. ^{(19,20,48,49,50)}  and they may be responsible for its  anti-inflammatory activity. ⁽⁵¹⁾

They may inhibit the production of other inflammatory substances including COX-1and 2, leukotriene-B4 and the activity of 5-lipoxygenase and nitric oxide synthase.^{(52, 53)} Green tea catechins may also protect cartilage by inhibiting proteoglycan and collagen breakdown.⁽⁵⁴⁾ Green tea polyphenols seem to lessen joint degeneration in laboratory models of rheumatoid arthritis. ⁽⁵⁵⁾ Green tea also contains plant estrogens including beta-sitosterol. ⁽⁴¹⁾

 

Green tea contains 2% to 4% caffeine or 10-80 mg caffeine per cup.⁽⁵⁶⁾ a typical amount is 35-60mgs per cup. The caffeine in green tea stimulates the central nervous system (CNS), heart, muscles, and possibly blood pressure.⁽⁵⁷⁾ Caffeine is thought to increase the release of neurotransmitters such as dopamine.⁽⁵⁸⁾ Caffeine also decreases airway resistance and stimulates respiration.⁽⁵⁹⁾ Caffeine may decrease GABA and Serotonin  neurotransmitters in the Central Nervous System. ⁽⁵⁸⁾ Caffeine stimulates stomach acid secretion, and increases fight or flight chemicals in the body.⁽⁶⁰⁾ Caffeine can have positive stimulating effects on the heart.⁽⁵⁹⁾ Caffeine can also immediately raise blood pressure, but might not have this effect in habitual users. ⁽⁵⁷⁾

Caffeine doesn't substantially affect the fluid status of people who drink caffeinated beverages on a regular basis. ^(61,62)

The caffeine content is also thought to be responsible for green tea's effects on mental performance. ⁽¹³⁾

Some preliminary studies show that flavonoids found in green tea might reduce heart disease risk factors lipoprotein oxidation. However, green tea doesn't reduce inflammation, vascular reactivity, or lipid oxidation. ^{(63,64,65,66,67)}

Caffeine has been reported to cause increases and decreases in blood glucose.

Green tea may protect against some kinds of cancer.

Green tea polyphenols also appear to have activity against human wart virus and related cervical changes and genital warts ^(20,68) but the mechanism of action for this is not known.

The polyphenols in green tea appear to reduce the cellular adhesiveness of bacteria associated with dental disease. ⁽³⁸⁾ Some evidence suggests that green tea might be useful in skin disorders such as excess hair, acne and also male pattern baldness. ⁽⁷⁰⁾

Green tea is thought to be beneficial for preventing skin damage and cancer from ultraviolet radiation. Areas of skin where green tea extracts were applied had fewer sunburned cells and less damage to skin cells. ⁽⁷¹⁾

Green tea is also used for weight loss. Early evidence indicates that a green tea extract rich in catechins can increase calorie and fat metabolism. The caffeine, catechin, and theanine constituents of green tea might contribute to this effect. ^(72,73,74) Caffeine increases resting energy expenditure and cellular heat production. ⁽⁷⁵⁾  

Tannins in green tea can reduce diarrhea and the polyphenols in green tea might have a beneficial effect on the gut flora.. ⁽⁷⁶⁾

For prevention of Parkinson's disease, caffeine in green tea may help to maintain levels of dopamine in the central nervous system by preventing the inhibition of dopaminergic transmission. These actions help reduce the expression of symptoms of Parkinson’s disease. ⁽²⁸⁾

Protecting people from developing Alzheimer's disease has got to be a major priority for aging Western populations. Early studies suggests that catechins in Green tea may prevent oxidation and cell death of neurons, which may help resist cell damage and maintain health. ⁽⁷⁷⁾

Population studies suggest that drinking green tea for at least ten years increases bone mineral density. The exact mechanism for the effects on bone is unknown, but several possibilities have been suggested. Tea leaves contain fluoride, which might slow osteoporosis. Tea also contains flavonoids and phytoestrogens, which might affect bone mineral density. Other proposed mechanisms include inhibition of bone resorption and effects on mineral metabolism by polyphenols and tannins. ⁽⁴⁴⁾

 

Adverse reactions.

  

Green tea can cause digestive upset and dizziness, insomnia and agitation and confusion. These effects are more common with higher doses of green tea or green tea extract, equivalent to 5-6 liters of tea per day. ^(9,78)

There have been at least 14 cases of liver toxicity, usually linked to green tea extract products in pill form. ^(79,80) However, there has been at least one report associated with consumption of a green tea-containing beverage. ⁽⁸⁰⁾ In most reported cases, green tea products were not assessed to determine if any contaminants were present. In most cases, liver function returned to normal after discontinuation of the green tea product. ^(79,80)

 

Interaction with herbs and supplements.

 

Anticoagulant/antiplatelet herbs and supplements:

There have been no reported cases of interaction with warfarin (this a pharmaceutical blood thinning agent).

Caffeine containing herbs and supplements: Other natural products that contain caffeine include coffee, black tea, oolong tea, guarana, mate, cola, and others. Some supplements for energy may contain caffeine; check the label.

Avoid large amounts of green tea along with supplements aimed at the market for sportspeople that contain creatine, caffeine or ephedra.^(83,84)

Liver toxic herbs and supplements: Theoretically, avoid taking green tea supplements with other hepatotoxic herbs or supplements as there might be additive effects. ^(79,85) Check out herbs you want to use with Green Tea and avoid the combination if there are concerns about liver function.

Iron: Like black tea, green tea appears to reduce absorption of iron from foods. ^(86,87) However, a study of iron-deficient elderly patients suggests that concomitant use doesn't alter iron absorption in this population. ⁽⁸⁹⁾ Iron levels are not affected in people with adequate iron intake.  Theoretically, green tea might reduce the absorption of iron supplements. For most patients, this effect will not be clinically significant. On this account patients with iron deficiency are advised to consume black tea and green tea between meals. ⁽⁸⁷⁾

 

Interactions with drugs.

There is preliminary evidence that green tea might enhance the effects of doxorubicin (Adriamycin) on cancer cells. ⁽⁶⁹⁾

Caffeine accounts for most of the side effects for green tea. If you are on medication or need to start medication read the drug insert leaflet carefully. If there is an interaction with caffeine, or black tea or coffee be aware that green tea may have the same interaction.

 

Stimulants. Read the drug leaflet any nervous system stimulation medicine including amphetamines.

 

Drugs that inhibit caffeine metabolism; These include cimetidine (reduces stomach acid), fluconazole (anti-fungal), mexilitene (prescribed for heartbeat irregularities), fluvoxamine (antidepressant). Avoid green tea supplements or consult a medical herbalist.

Drugs that decrease caffeine clearance: terbinafine (prescribed for fungal infection of toe nails), quinolone antibiotics (the commonest prescribed is ciproflaxacin, apart from nalidixic acid all others end with –acin).

Hepatotoxic drugs. Avoid of green tea supplements.

Estrogens. The effect of caffeine on estrogens is complicated and depends on race and the dose of caffeine. High caffeine levels can elevate estrogens and low doses can stimulate. An average amount in daily intake of green tea is unlikely to be clinically significant but may be relevant to supplement doses.⁹³

Drugs that reduce caffeine clearance; theophylline.

Warfarin. No reports have been noted with normal consumption, observe the usual vigilance.

Interactions with foods. Avoid excess caffeine intake when used in conjunction with black tea and coffee. Because the effects of caffeine are dose related avoid excessive amount of caffeine intake. The amount of caffeine in coffee is extremely variable, check the packaging or server, black tea averages 30-80mgs per cup. Check the amount in soft drinks and avoid high caffeine energy drinks.

Green tea appears to reduce absorption of iron from non-meat food sources. If you are concerned about this drink green tea between meals.

Adding milk to your green tea may reduce the benefits of green tea as the milk may reduce the absorption of some of the helpful constituents.

Interaction with laboratory tests.

Inform your medical provider if you are taking green tea supplements. Drinking 4-6 cups of green tea per day is unlikely to affect laboratory tests any more than 1-3 cups of coffee.

Interactions with diseases and conditions.

Generalized anxiety or nervous excitability: avoid caffeinated beverages or supplements.

Diabetes: caffeine may affect the presentation of hypoglycemic attacks. Avoid sudden increases or decreases of caffeine intake and monitor blood sugars more carefully if changing the amount of caffeine in your diet.

Glaucoma: Intake of caffeinated beverage (>/=180 mg caffeine) may not be recommended for patients with normotensive glaucoma or ocular hypertension.

Bleeding time: Caffeine is reported to have antiplatelet activity however, this interaction has not been reported in humans.

Heart rhythm irregularities: Caffeine in green tea can induce cardiac arrhythmias in sensitive individuals use with caution.

 

Dosage.

It is difficult to be precise with dosage of green tea as much depends on the duration of brewing and the quality of the raw herb.

Infusion: 1-6 cups for men per day and 1-4 cups for women per day if using one tsp. of the herb per cup of boiling water.

Powder/capsule: 1500 mg per day.

Ostearthritis

Oral: Doses of green tea vary significantly, but usually range between 1-10 cups daily. The commonly used dose of green tea is based on the amount typically consumed in Asian countries, which is about 3 cups per day, providing 240-320 mg of polyphenols.

The typical dose of caffeine:

• For headache or restoring mental alertness is up to 250 mg per day. ^(90.91)
• For improving cognitive performance, tea providing 60 mg of caffeine, or approximately one cup per day, has been used. ⁽¹³⁾
• For reducing cholesterol, 10 or greater cups per day has been associated with decreased cholesterol levels. ⁽²²⁾ Theaflavin-enriched green tea extract, 375 mg daily for 12 weeks, has also been used for cholesterol reduction. ⁽²¹⁾
• For preventing breast cancer or breast cancer recurrence, three or more cups of green tea per day have been used. ⁽³⁶⁾
• For human papilloma wart virus (HPV) infected cervical lesions, green tea extract, 200 mg daily alone or in combination with topical green tea ointment, for 8-12 weeks has been used. ⁽²⁰⁾
• For preventing Parkinson's disease consuming as little as 124-208 mg of caffeine (approximately 1-3 cups of green tea) daily offers benefit.⁽²⁸⁾ Women in particular may benefit from these moderate amounts, men appear to require higher amounts. This needs to be balanced with the adverse effects of excess caffeine. ⁽²⁹⁾

 

References.

1. Mitscher LA, Mitscher LA, Jung M, Shankel D, et al. Chemoprotection: A review of the potential therapeutic antioxidant properties of green tea (Camellia sinensis) and certain of its constituents. Med Res Rev 1997;17:327-65.
2. Nemecz G. Green tea. US Pharm 2000;May:67-70.
3. Inoue M, Tajima K, Hirose K, et al. Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan. Cancer Causes Control 1998;9:209-16.
4. Tajima K, Tominaga S. Dietary habits and gastro-intestinal cancers: a comparative case-control study of stomach and large intestinal cancers in Nagoya, Japan. Jpn J Cancer Res 1985;76:705-16.
5. Kono S, Ikeda M, Tokudome S, Kuratsune M. A case-control study of gastric cancer and diet in northern Kyushu, Japan.

Jpn J Cancer Res 1988;79:1067-74.

1. Ji BT, Chow WH, Yang G, et al. The influence of cigarette smoking, alcohol, and green tea consumption on the risk of carcinoma of the cardia and distal stomach in Shanghai, China. Cancer 1996;77:2449-57.
2. Yu GP, Hsieh CC. Risk factors for stomach cancer: a population-based case-control study in Shanghai. Cancer Causes Control 1991;2:169-74.
3. Zhang M, Binns CW, Lee AH. Tea consumption and ovarian cancer risk: a case-control study in China. Cancer Epidemiol Biomarkers Prev 2002;11:713-8.
4. Pisters KM, Newman RA, Coldman B, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol 2001;19:1830-8.
5. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html.
6. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid= 786bafc6f6343634fbf79fcdca7061e1&rgn=div5&view= text&node=21:3.0.1.1.13&idno=21
7. Castellanos FX, Rapoport JL. Effects of caffeine on development and behavior in infancy and childhood: A review of the published literature. Food Chem Toxicol 2002;40:1235-42.
8. Durlach PJ. The effects of a low dose of caffeine on cognitive performance. Psychopharmacology (Berl) 1998;140:116-9.
9. Hindmarch I, Quinlan PT, Moore KL, Parkin C. The effects of black tea and other beverages on aspects of cognition and psychomotor performance. Psychopharmacol 1998;139:230-8.
10. Mitscher LA, Mitscher LA, Jung M, Shankel D, et al. Chemoprotection: a review of the potential therapeutic antioxidant properties of green tea (Camellia sinensis) and certain of its constituents. Med Res Rev 1997;17:327-65.
11. Bushman JL. Green tea and cancer in humans: a review of the literature. Nutr Cancer 1998;31:151-9.
12. Wakai K, Ohno Y, Obata K. Prognostic significance of selected lifestyle factors in urinary bladder cancer. Jpn J Cancer Res 1993;84:1223-9.
13. Ohno Y, Aoki K, Obata K, et al. Case-control study of urinary bladder cancer in metropolitan Nagoya. Natl Cancer Inst Monogr 1985;69:229-34.
14. Nemecz G. Green tea. US Pharm 2000;May:67-70.
15. Ahn WS, Yoo J, Huh SW, et al. Protective effects of green tea extracts (polyphenon E and EGCG) on human cervical lesions. Eur J Cancer Prev 2003;12:383-90.
16. Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: A randomized controlled trial. Arch Intern Med 2003;163:1448-53.
17. Imai K. Nakachi K. Cross-sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ 1995;310:693-6.
18. Heseltine D, Dakkak M, woodhouse K, et al. The effect of caffeine on postprandial hypotension in the elderly. J Am Geriatr Soc 1991;39:160-4
19. Rakic V, Beilin LJ, Burke V. Effect of coffee and tea drinking on postprandial hypotension in older men and women. Clin Exp Pharmacol Physiol 1996;23:559-63.
20. Li N, Sun Z, Han C, Chen J. The chemopreventive effects of tea on human oral precancerous mucosa lesions. Proc Soc Exp Biol Med 1999;220:218-24.
21. Zhang M, Binns CW, Lee AH. Tea consumption and ovarian cancer risk: a case-control study in China. Cancer Epidemiol Biomarkers Prev 2002;11:713-8.
22. Larsson SC, Wolk A. Tea consumption and ovarian cancer risk in a population-based cohort. Arch Intern Med 2005;165:2683-6.
23. Ross GW, Abbott RD, Petrovitch H, et al. Association of coffee and caffeine intake with the risk of parkinson disease. JAMA 2000;283:2674-9.
24. Ascherio A, Zhang SM, Hernan MA, et al. Prospective study of caffeine intake and risk of Parkinson's disease in men and women. Proceedings 125th Ann Mtg Am Neurological Assn. Boston, MA: 2000;Oct 15-18:42.
25. Inoue M, Tajima K, Hirose K, et al. Tea and coffee consumption and the risk of digestive tract cancers: data from a comparative case-referent study in Japan. Cancer Causes Control 1998;9:209-16.
26. Tajima K, Tominaga S. Dietary habits and gastro-intestinal cancers: a comparative case-control study of stomach and large intestinal cancers in Nagoya, Japan. Jpn J Cancer Res 1985;76:705-16.
27. Kuriyama S, Shimazu T, Ohmori K, et al. Green tea consumption and mortality due to cardiovascular disease, cancer, and all-cause mortality. JAMA 2006;296:1255-65.
28. Seely D, Mills EJ, Wu P, et al. The effects of green tea consumption on incidence of breast cancer and recurrence of breast cancer: a systematic review and meta-analysis. Integr Cancer Ther 2005;4:144-55
29. Suzuki Y, Tsubono Y, Nakaya N, et al. Green tea and the risk of breast cancer: pooled analysis of two prospective studies in Japan. Br J Cancer 2004;90:1361-3.
30. Wu AH, Yu MC, Tseng CC, et al. Green tea and risk of breast cancer in Asian Americans. Int J Cancer 2003;106:574-9.
31. Inoue M, Tajima K, Mizutani M, et al. Regular consumption of green tea and the risk of breast cancer recurrence: follow-up study from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan. Cancer Lett 2001;167:175-82.
32. Iso H, Date C, Wakai K, et al; JACC Study Group. The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults. Ann Intern Med 2006;144:554-62.
33. Krahwinkel T, Willershausen B. The effect of sugar-free green tea chew candies on the degree of inflammation of the gingiva. Eur J Med Res 2000;5:463-7.
34. Yang YC, Lu FH, Wu JS, et al. The protective effect of habitual tea consumption on hypertension. Arch Intern Med 2004 26;164:1534-40.
35. Taubert D, Roesen R, Schomig E. Effect of cocoa and tea intake on blood pressure: a meta-analysis. Arch Intern Med 2007;167:626-34.
36. Schabath MB, Hernandez LM, Wu X, et al. Dietary phytoestrogens and lung cancer risk. JAMA 2005;294:1493-1504.
37. Chantre P, Lairon D. Recent findings of green tea extract AR25 (Exolise) and its activity for the treatment of obesity. Phytomedicine 2002;9:3-8.
38. Phung OJ, Baker WL, Matthews LJ, et al. Effect of green tea catechins with or without caffeine on anthropometric measures: a systemic review and meta-analysis. Am J Clin Nutr 2010;91:73-81.
39. Wu CH, Yang YC, Yao WJ, et al. Epidemiological evidence of increased bone mineral density in habitual tea drinkers. Arch Intern Med 2002;162:1001-6.
40. Jian L, Xie LP, Lee AH, Binns CW. Protective effect of green tea against prostate cancer: a case-control study in southeast China. Int J Cancer 2004;108:130-5.
41. Bettuzzi S, Brausi M, Rizzi F, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res 2006;66:1234-40.
42. ˇChung LY, Cheung TC, Kong SK, et al. Induction of apoptosis by green tea catechins in human prostate cancer DU145 cells. Life Sci 2001;68:1207-14.
43. Khokhar S, Magnusdottir SG. Total phenol, catechin, and caffeine contents of teas commonly consumed in the United Kingdom. J Agric Food Chem 2002;50:565-70.
44. Henning M, Fajardo-Lira C, Lee HW, et al. Catechin content of 18 teas and a green tea extract supplement correlates with the antioxidant capacity. Nutr Cancer 2003;45:226-35.
45. Mohseni H, Zaslau S, McFadden D, et al. COX-2 inhibition demonstrates potent anti-proliferative effects on bladder cancer in vitro. J Surg Res 2004;119:138-42 .
46. Choi JH, Chai YM, Joo GJ, et al. Effects of green tea catechin on polymorphonuclear leukocyte 5'-lipoxygenase activity, leukotriene B4 synthesis, and renal damage in diabetic rats. Ann Nutr Metab 2004;48:151-5.
47. Ahmed S, Rahman A, Hasnain A, et al. Green tea polyphenol epigallocatechin-3-gallate inhibits the IL-1 beta-induced activity and expression of cyclooxygenase-2 and nitric oxide synthase-2 in human chondrocytes. Free Radic Biol Med 2002;33:1097-105.
48. Adcocks C, Collin P, Buttle DJ. Catechins from green tea (Camellia sinensis) inhibit bovine and human cartilage proteoglycan and type II collagen degradation in vitro. J Nutr 2002;132:341-6.
49. Haqqi TM, Anthony DD, Gupta S, et al. Prevention of collagen-induced arthritis in mice by a polyphenolic fraction from green tea. Proc Natl Acad Sci U S A 1999;96:4524-9.
50. Kaegi E. Unconventional therapies for cancer: 2. Green tea. The Task Force on Alternative Therapies of the Canadian Breast Cancer Research Initiative. CMAJ 1998;158:1033-5.
51. Nurminen ML, Niittynen L, Korpela R, Vapaatalo H. Coffee, caffeine and blood pressure: a critical review. Eur J Clin Nutr 1999;53:831-9.
52. Sinclair CJ, Geiger JD. Caffeine use in sports. A pharmacological review. J Sports Med Phys Fitness 2000;40:71-9.
53. Howell LL, Coffin VL, Spealman RD. Behavioral and physiological effects of xanthines in nonhuman primates. Psychopharmacology (Berl) 1997;129:1-14.
54. Chou T. Wake up and smell the coffee. Caffeine, coffee, and the medical consequences. West J Med 1992;157:544-53.
55. Stookey JD. The diuretic effects of alcohol and caffeine and total water intake misclassification. Eur J Epidemiol 1999;15:181-8.

1. Grandjean AC, Reimers KJ, Bannick KE, Haven MC. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr 2000;19:591-600.
2. Leenen R, Roodenburg AJ, Tijburg LB, et al. A single dose of tea with or without milk increases plasma antioxidant activity in humans. Eur J Clin Nutr 2000;54:87-92.
3. Hodgson JM, Puddey IB, Croft KD, et al. Acute effects of ingestion of black and green tea on lipoprotein oxidation. Am J Clin Nutr 2000;71:1103-7.
4. Leung LK, Su Y, Chen R, et al. Theaflavins in black tea and catechins in green tea are equally effective antioxidants. J Nutr 2001;131:2248-51.
5. Hodgson JM, Croft KD, Mori TA, et al. Regular ingestion of tea does not inhibit in vivo lipid peroxidation in humans. J Nutr 2002;132:55-8.
6. de Maat MP, Pijl H, Kluft C, Princen HM. Consumption of black and green tea had no effect on inflammation, haemostasis and endothelial markers in smoking healthy individuals. Eur J Clin Nutr 2000;54:757-63.
7. Bradley Pharmaceuticals. Veregen Prescribing Information. October 2006.
8. Stammler G, Volm M. Green tea catechins (EGCG and EGC) have modulating effects on the activity of doxorubicin in drug-resistant cell lines. Anticancer Drugs 1997;8:265-8.
9. Shaw JC. Green tea polyphenols may be useful in the treatment of androgen-mediated skin disorders. Arch Dermatol 2001;137:664.
10. Elmets CA, Singh D, Tubesing K, et al. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. J Am Acad Dermatol 2001;44:425-32.
11. Dulloo AG, Duret C, Rohrer D, 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.
12. Cronin JR. Green tea extract stokes thermogenesis: will it replace ephedra? Altern Comp Ther 2000;6:296-300.
13. Zheng G, Sayama K, Okubo T, et al. Anti-obesity effects of three major components of green tea, catechins, caffeine and theanine, in mice. In Vivo 2004;18:55-62.
14. Acheson KJ, Gremaud G, Meirim I, et al. Metabolic effects of caffeine in humans: lipid oxidation or futile cycling? Am J Clin Nutr 2004;79:40-6.
15. Weisburger JH. Tea and health: the underlying mechanisms. Proc Soc Exp Biol Med 1999;220:271-5
16. Choi YT, Jung CH, Lee SR, et al. The green tea polyphenol (-)-epigallocatechin gallate attenuates beta-amyloid-induced neurotoxicity in cultured hippocampal neurons. Life Sci 2001;70:603-14.
17. Jatoi A, Ellison N, Burch PA, et al. A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma. Cancer 2003;97:1442-6.
18. Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann Intern Med 2006;144:68-71.
19. Jimenez-Saenz M, Martinez-Sanchez, MDC. Acute hepatitis associated with the use of green tea infusions. J Hepatol 2006;44:616-9.
20. Wakabayashi K, Kono S, Shinchi K, et al. Habitual coffee consumption and blood pressure: A study of self-defense officials in Japan. Eur J Epidemiol 1998;14:669-73.
21. Hodgson JM, Puddey IB, Burke V, et al. Effects on blood pressure of drinking green and black tea. J Hypertens 1999;17:457-63.
22. Haller CA, Benowitz NL. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids. N Engl J Med 2000;343:1833-8.
23. Kockler DR, McCarthy MW, Lawson CL. Seizure activity and unresponsiveness after hydroxycut ingestion. Pharmacotherapy 2001;21:647-51.
24. Gloro R, Hourmand-Ollivier I, Mosquet B, et al. Fulminant hepatitis during self-medication with hydroalcoholic extract of green tea. Eur J Gastroenterol Hepatol 2005;17:1135-7.
25. Samman S, Sandstrom B, Toft MB, et al. Green tea or rosemary extract added to foods reduces nonheme-iron absorption. Am J Clin Nutr 2001;73:607-12.
26. Zijp IM, Korver O, Tijburg LB. Effect of tea and other dietary factors on iron absorption. Crit Rev Food Sci Nutr 2000;40:371-98
27. Merhav H, Amitai Y, Palti H, Godfrey S. Tea drinking and microcytic anemia in infants. Am J Clin Nutr 1985;41:1210-3
28. Kubota K, Sakurai T, Nakazato K, et al. [Effect of green tea on iron absorption in elderly patients with iron deficiency anemia]. Nippon Ronen Igakkai Zasshi 1990;27:555-8.
29. Migliardi JR, Armellino JJ, Friedman M, et al. Caffeine as an analgesic adjuvant in tension headache. Clin Pharmacol Ther 1994;56:576-86.
30. Smith A. Effects of caffeine on human behavior. Food Chem Toxicol 2002;40:1243-55.
31. Zhang M, Binns CW, Lee AH. Tea consumption and ovarian cancer risk: a case-control study in China. Cancer Epidemiol Biomarkers Prev 2002;11:713-8.
32. Schliep KC, Schisterman EF, Mumford SL, et al. Caffeinated beverage intake and reproductive hormones among premenopausal women in the BioCycle Study. Am J Clin Nutr. 2012;95(27):488-497.