http://en.wikipedia.org/wiki/Green_tea

Taxonomy

History•Green tea is made from the dried leaves of Camellia sinensis , a perennial evergreen shrub. Green tea has a long history of use, dating back to China approximately 5,000 years ago.

•Green tea has been used as traditional medicine in areas such as India, China, Japan and Thailand to help •everything from controlling bleeding and helping heal wounds to regulating body temperature, blood •sugar and promoting digestion.

Green or Black?•Green tea and black tea are derived from the same leaf. The difference lies in how they are processed.

•When making green tea the leaves are plucked processed immediately to prevent them from fermenting.

•Unfermented leaves contain large amounts of catechins, which are powerful disease fighters and potent antioxidants.

•When making black tea, the leaves are picked and are left to ferment. This changes the chemical structure of the catechins into substances called thearubigens and theaflavins, which have some health benefits but not nearly as many as the catechins.

Brewing and Dosage• Generally, 2.25 grams of tea per 6 ounces of water, or about one teaspoon of green tea per cup, should be used.

• The average 6-ounce cup of green tea contains between 50 and 100 mg catechins.

• Most studies have concluded that you need 3-10 cups of green tea per day, or up to 1,000 mg. of catechins in order to get the healthy benefits of green tea

What Can Green Tea Prevent?•Alzheimer’s disease •Parkinson’s disease•Cancer• HIV•multiple sclerosis •LDL cholesterol•Cardiovascular disease•Raise metabolism•insulin sensitivity•hypertension •tooth decay•cholera • And anything else you can think of….

Active Constituents[25]

Catechins [25]

• family of flavan-3-ols – Sub group of flavanoids –technically not a

flavanoid due to lack of carbonyl group

• Are polyphenyl groups which have been shown to have anti-oxidant and anti-carcinogenic properties

• Catechins make up slightly less than 30% of dry weight

Catechins• Epicatechin and

epogallocatechin most commonly found in nature

• Epigallocatechin gallate most frequent catechin found in Green Tea– Thought to hold most

antioxidant activity– Gallic acid attached to

catechin• Gallic acid found freely and

within tannins in many other plants

Other Active Components• Vitamin C

– antioxidant• B Vitamins

– Metabolize carbohydrates– Manufacture fatty acids and amino acids

• Vitamin E– Antioxidant

• Fluoride– Protection of tooth decay and gum disease

– Caffeine (3-4%)– About a quarter of that of coffee

The Asian Paradox[1]

• Next to Green Tea, cigarettes are mostly widely consumed product in Asia

• Asians have some of the lowest cardio-related death rates in the world

• Clinical studies have been performed to view different aspects and health benefits of green tea that lead to this paradox

Pharmacokinetics[2]

• Changes in blood count and blood chemistry profiles not significant in individuals given EGCG dosages

• Non-significant difference in amount of tea catechins found after initial dosage and 4 weeks later after daily regimen of EGCG at 800 mg/day and 400 mg/ day

• >60% increase in the systemic availability of free EGCG after chronic green tea polyphenol administration at 800 mg/day

Pharmacokinetics[2]

• Side Effects found in this study:– Excess gas– Upset stomach– Heartburn– Abdominal pain– Dizziness– Headache– Muscle pain

• All reported as mild events

Pharmacokinetics[3]

• Found that EGCG levels rose significantly at about 3 hours and peaked between 8-15 hours after a single dosage

• 90% of EGC and EC excreted in urine between 0-8 hours

• Supports other study with similar results

Clinical Trials; Heart Disease• In a double-blinded, randomized, placebo-controlled trial ,240

adults were given either theaflavin-enriched green tea extract in form of 375mg capsule daily or a placebo. After 12 weeks, patients in the tea extract group had significantly LDL cholesterol and total cholesterol (16.4% and 11.3% lower than baseline, p<0.01) than the placebo group [4]

• A meta-analysis examining the effect of green tea on cardiovascular heart health found a decrease in the rate of heart disease outcomes with increasing tea consumption. [5] However, two studies from the United Kingdom [6][7] and two studies from the United States [8][9] indicated an increased risk with increasing tea consumption, whereas the other studies indicated a decrease in risk.

Clinical Trials; Cancer• EGCG and other tea polyphenols inhibited

growth of human lung cancer cell line, PC-9 cells with G2/M arrest. [10]

• Many studies have studied the inhibitory effects of EGCG and green tea extract on carcinogenesis in various organs of rodents [11][12][13]

Skin Cancer[14]

• 2 groups of lab mice (30 each) subjected to equal amounts of UVB radiation

• One group treated with 1.25% green tea drinking water and other with 2.5% green tea drinking water, control with distilled water

• Decreased number of skin tumors and substantially reduced size of tumors

Skin Cancer[14]

Breast Cancer [15]

• In vitro– green tea catechins inhibits proliferation of ER-positive

MCF-7 breast cancer cells • In vivo

– Mice studied had increased levels of catechins in mammary fat pads and levels were relative to how much tea was administered to each group

• In both aspects of the study catechins used with tamoxifen, a orally active selective estrogen receptor modulator, showed the best results in comparison to catechins or tamoxifen alone

Clinical Trials; Obesity• Mice that were fed high fat diets supplemented with tea

catechins for 11 months resulted in a significant reduction of diet-induced weight gain [16]

• Ingestion of tea catechins stimulated O2 consumption and energy expenditure and decreased the respiratory quotient in humans. [17]

• Injection of EGCG modulates appetite and reduces food intake through the leptin receptor-independent pathway in rats.[18]

Clinical Trials; Diabetes

• Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat models of diabetes [21]

• Some studies have shown that plasma glucose levels in diabetic rats are lowered when the rats are given (-) epicatechin [19] [20]

Gastrointestinal [22]

• Test of each catechin found in green tea to find which best treats GI infection by Helicobacter pylori – chronic gastritis, peptic ulceration, and gastric cancer

• In vivo study– Mongolian gerbils inoculated with equal levels of H. pylori– fed different diet containing (0, .5, 1, or 2%) catechins for 2 weeks– H. pylori was eradicated in about 10% of the gerbils – In ones not eradicated, 10-36% decrease of H. pylori– Similar to success rate in human cell in vitro studies with antibiotics– More studies need on impacts of catechins on H. pylori other than

eradication

Epidemiological Studies[23]

• Few have been done and ones completed take place in Asia

• So many variables to account for, e.g. smoking, alcohol consumption, diet, exercise it is hard to derive results

• One study looked at over 18000 men from Shanghai and said there was a slight decrease in cancer rates, but results seem to be unverifiable due to high variability of subjects

Contraindications[24]

• Caffeine only substance that has potential to do harm– Pregnant/nursing women should limit caffeine

intake

• Should not be taken if used with Warfarin– Vitamin K interacts with anticoagulation

References1. Sumpio, Bauer E. et al. “Green tea, the “Asian paradox,” and cardiovascular disease.”

Journal of American College of Surgeons. 2006. 202:5, pp. 813- 825. 2. Chow, Sherry, 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. 9, pp. 3312-3319.

3. Lee, M.J., et al. “Pharmacokinetics of tea catechins after ingestion of green tea and epigallocatechin-3-gallate by humans: formation of different metabolites and individual variability.” Cancer Epidemiol Biomarkers Prev. 2002. 10:1, pp.1025-1032.

4. David J. Baron et al. “Cholesterol-Lowering Effect of a Theaflavin-Enriched Green Tea Extract.” Arch Intern Med. 2003.163:1448-1453.

5. Ulrike Peters et al. “Does Tea Affect Cardiovascular Disease? A Meta-Analysis.” American Journal of Epidemiology. 2001. 154:6 pp. 495-503.

6. Woodward M, Tunstall-Pedoe H. “Coffee and tea consumption in the Scottish Heart Health Study follow up: conflicting relations with coronary risk factors, coronary disease, and all cause mortality.” J Epidemiol Community Health. 1999. 53: 481-487.

7. Hertog MG, Sweetnam PM, Fehily AM, et al. “Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study.” Am J Clin Nutr. 1997. 65: pp. 1489–94.

8. Rosenberg L, Palmer JR, Kelly JP, et al. “Coffee drinking and nonfatal myocardial infarction in men under 55 years of age.” Am J Epidemiol. 1988. 128: pp. 570– 578.

9. Rimm EB, Katan MB, Ascherio A, et al. “Relation between intake of flavonoids and risk for coronary heart disease in male health professionals.” Ann Intern Med.

10. S. Okabe, M. Suganuma, M. Hayashi, E. Sueoka, A. Komori, H. Fujiki. “Mechanisms of growth inhibition by tea polyphenols on human lung cancer cell line, PC-9” Japan J. Cancer Res. 1997. 88: pp.639–643.

11. M. Suganuma, Chemoprevention of cancer, in: T. Bowden, S. Fischer Eds.. “Comprehensive Toxicology.” Elsevier, UK.1997. pp. 453–471.

12. Bushman JL. “Green tea and cancer in humans: a review of the literature.” Nutr Cancer. 1998. 31:3 pp.151-159.

13. Fujiki H, Suganuma M, Okabe S, et al. “Cancer inhibition by green tea.” Mutation Research. 1998. pp. 307-310.

14. Wang, Zhi-Yuan, et al. “Inhibitory effect of green tea in the drinking water on tumorigenesis by ultraviolet light and 12-O-tTetradecanoylphorbol-13- acetate in the skin of SKH-1 mice.” Cancer Research. 1992. 52, pp. 1162-1170.

15. Sartippour, Maryam R. et al. “The combination of green tea and tamoxifen is effective against breast cancer.” Carcinogenesis. 2006. 27:12, pp. 2424-2433.

16. T. Murase et al. “Beneficial effects of tea catechins on diet-induced obesity: stimulation of lipid catabolism in the liver.” International Journal of Obesity. 2002. 26:11, pp. 1459-1464.

17. 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 humnas.” Am J Clin Nutr . 1999. 70, pp.1040-1045.

18. Kao YH, Hiipakka RA, Liao S. “Modulation of obesity by a green teacatechin.“ Am J Clin Nutr. 2000. 72, pp. 1232 – 1234.

19. Sheehan EW,Zematis MA . “A constituent of Pterocarpus Marsupium, (-)epicatechin, as a potential antidiabetic agent.” J Nat Prod. 1988. 46, pp. 232–234.

20. Chakravarthy BK, Gupta S, Gode KD. “Functional beta cell regeneration in the islets of pancreas in alloxan induced diabetic rats by (-)-epicatechin.” Life Sci. 1982. 31, pp. 2693–2697.

21. Lucy Sun Hwang et al. “Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model.” European Journal of Nutrition. 2004. 43:2, pp.116-124.

22. Mabe, Katsuhiro, et al. “In Vitro and In Vivo Activities of Tea Catechins against Helicobacter pylori.” Antimicrobial Agents and Chemotherapy. 1999. 43:7, pp. 1788–1791.

23. Sun, Can-Lan, et al. “Urinary tea polyphenols in relation to gastric and esophageal cancers: a prospective study of men in Shanghai, China.” Carcinogenesis. 2002. 23:9, pp. 1497 -1503.

24. Wolters Kluwer Health. “Green Tea.” 2006. Green Tea Information. Accessed on 6, April, 2008. < http://www.drugs.com/npc/green-tea.html>.

25. Zaveri, Nurulain T. “Green tea and its polyphenolic catechins: Medicinal uses in cancer and noncancer applications.” Life Sciences. 2006. 78:18, pp. 2073- 2080.