Green tea has been considered a medicinal remedy in Chinese tradition dating back over 4,000 years. The observed health benefits of this folk remedy, now being validated by modern scientific investigation, include: lowers total cholesterol, increases HDL cholesterol levels, reduces blood pressure, acts as a "blood thinner" by inhibiting platelet aggregation, reduces risk of heart attack and stroke, reduces risk of cancer, enhances immune cell function, improves digestion, and prevents dental cavities and gingivitis.

Green tea catechins are definitely included in a broad brush approach to the health benefits of flavonoids, which include potential for the prevention and treatment of cardiovascular disease, cancer, inflammatory conditions, asthma, periodontal disease, liver disease, cataracts, and macular degeneration. Epidemiological studies suggest that populations drinking 8-10 cups of Green tea daily have markedly reduced rates of gastrointestinal cancers as well as lower rates of cancer of the pancreas, breast, and lung. Japan, for example, has a very low incidence of cancer which is thought secondary to their relatively high intake of Green tea.

Laboratory studies supporting the cancer protective effect of Green tea demonstrate that catechins and other polyphenols inhibit free radical precursors to cancer as well as block the effects of other tumor promoters including estrogen, growth factors, and cancer causing chemicals like benzopyrenes and nitrosamines.

The anticancer effect of Green tea polyphenols, specifically catechins, in human and animal studies has been impressive enough for the National Cancer Institute to include Green tea polyphenols in its "Designer Nutrient Program", a research effort to investigate the cancer preventative and therapeutic benefits of foods and food products.

Extensive international research reveals that Green tea catechins have apoptic activity in human cancer cell lines including prostate, skin, lymphoma, ovarian, colon, adenocarcinoma, liver breast, lung, and stomach cancers.

Green tea consumption is protective for gastrointestinal cancers in large studies. Green tea polyphenols have shown promise in vitro as antineoplastic substances, due to their ability to scavenge oxidative initiators of neoplasia (Yoshikawa, Picard).

Laboratory and epidemiological studies indicate Green tea catechins exert a protective effect against prostate cancer. Green tea drinkers have lower rates of prostate cancer with the lowest rate of prostate cancer in China with the highest consumption of tea (Gupta).

Antimutagenic properties of catechins against tumors found in laboratory animals were reproduced recently when tested against four human tumor cell lines from carcinomas of the breast, colon, lung and melanoma. Epigallocatechin gallate was the most potent catechin against all four tumor lines. It was recommended that in vivo animal trials be conducted prior to consideration of testing Green tea catechins against cancer in humans.

Green tea inhibits cancer in laboratory studies by several mechanisms including enhanced cell-mediated immunity, increased glutathione-S-transferase activity (increases glutathione, a powerful intracellular antioxidant), inhibits tumor growth rate, blocks tumor-induced inhibition of intracellular communication, and scavenges free radicals. Green tea polyphenols specifically block the formation of carcinogenic nitrosamines.

When volunteers were given Green tea in combination with 300 mg of sodium nitrate and 300 mg of proline, the formation of nitrosoproline was strongly inhibited (Stich).

Daily intake of Green tea polyphenols appears to have multiple health benefits summarized below, including reduced risk of cancer and cardiovascular disease:

• Catechins protect against radiation, including increased survival and decreased incidence of radiation-induced tumors.

• Catechins have antimutagenic activity against both spontaneous and chemically-induced mutations.

• Catechins have anti-tumor activity, inducing phase I and II metabolic enzymes that increase the formation and excretion of detoxified metabolites of carcinogens, slowing the rate of cell replication and thus the growth and development of neoplasms, and preventing spontaneous and chemically-induced cancer development.

• Catechins are powerful antioxidants that inhibit oxidation of LDL-cholesterol, reduce cholesterol levels, and reduce body fat, resulting in a decreased risk of heart disease.

• Catechins have regulatory effects on blood pressure and high blood-pressure induced strokes. Individuals consuming more than five cups a day having a 500% decrease in stroke incidence.

• Catechins have antibacterial activity against foodborne pathogenic bacteria and cavity-inducing bacteria, modifying the intestinal microflora, reducing undesirable bacteria and increasing beneficial bacteria.

• Catechins have an antihyperglycemic action, lowering both blood-glucose and normalizing insulin release.

• Catechins show antiviral effects, inhibiting reproduction of numerous viruses including influenza and human immunodeficiency virus.

Additional research is being published almost weekly on the remarkable healing properties of Green tea catechins. Important studies are summarized briefly below.

Green tea also reduces oxidative stress caused by smoking, including decreased oxidative DNA damage, reduced lipid peroxidation, and reduced urine levels of free radicals. Green tea appears to significantly lower risk of cardiovascular disease, even having a protective effect in smokers. Japanese males, for example, have a relatively low risk of heart disease despite the fact 75% of adults smoke tobacco.

This "Japanese Paradox" is similar to the "French paradox" in that the polyphenols in Green tea have a protective effect against heart disease and cancer just like the polyphenols in red wine protect the French against cardiovascular disease in spite of their high fat diets.

In Japanese males over 40, the protective effects of Green tea against heart disease and cancer increased exponentially in proportion to average daily tea intake comparing risk in men drinking less than three, four to nine, and more than ten cups of tea daily (Imai).

Green tea increases thermogenesis or fat oxidation. Green tea catechins increased 24-hour energy expenditure, decreased respiratory quotient, and increased urinary excretion of nitrogen and catecholamines compared to controls and those taking caffeine alone. Green tea catechins independent of caffeine inhibit catechol O-methyltransferase, an enzyme that degrades norepinephrine, causing a more sustained effect of norepinephrine (adrenalin) on thermogenesis and energy production from burning of fatty acids. This occurred without a stimulatory increase in heart rate, distinguishing Green tea from sympathomimetic drugs, which can have adverse cardiovascular side effects (Dulloo).

Green tea inhibits viral infections by a mechanism similar to elderberry flavonoids. Catechins bind to the hemagglutinin of the influenza virus and inhibit its absorption to the target cell, thereby inhibiting its ability to infect the target cell (Nakayama).

Green tea correlates inversely with total serum cholesterol in a study of 1300 Japanese males. Cholesterol level was an average of 8 mg/dl lower in males drinking 9 or more cups of Green tea per day compared to those consuming zero to two cups per day (Kono).

Green tea lowers cholesterol by increasing fecal lipid excretion in lab animals and may reduce levels in humans by a similar mechanism of increasing bile acids (Yang).

In summary, studies confirm that flavonoids in Green tea have antibacterial, anti-inflammatory, antiallergic, antimutagenic, antiviral, antineoplastic, antithrombotic, and vasodilatory activity. Catechins from Green tea are potent antioxidants that scavenge hydroxyl radicals, superoxide anions, and lipid peroxyl radicals. In most experimental studies catechins demonstrate superior antioxidant properties than Vitamin C or E.

Green tea catechins have bacteriocidal activity at concentrations of catechins found in a single cup of Green tea.

Green tea catechins inhibit oxidation of LDL cholesterol, lower total serum cholesterol levels, and increase levels of HDL cholesterol.

Green tea also contains components unrelated to the flavonoids. Approximately 3.5% caffeine, 6.5% lignan, 1.5% organic acids, 15% proteins, and 2% theanine, an amino acid that has recently been shown to reduce blood pressure. Standardized Green tea extracts contain on average 60-80% total polyphenols, but may be as high as over 90%.

Green tea contains about 50-100 mg of caffeine, the principal ingredient responsible for the social popularity of Green tea. Caffeine stimulates the central nervous system, respiratory, cardiac, and skeletal muscle systems. Caffeine causes coronary artery dilation, smooth muscle relaxation, and diuresis. Long-term studies on caffeine consumption, interesting, refute acute studies that caffeine is harmful to the cardiovascular system and aggravates hypertension (Robertson). Most Green tea extracts, including the extract in Ellagic Insurance Formula, have been decaffeinated.

Studies suggest that 200-400 mg of Green tea polyphenols approximates the amount of catechins found in 8-10 cups of tea daily. Unfortunately, it is difficult for most individuals to consume the 5-10 cups of Green tea daily that research has shown to be beneficial. One option is to take catechins concentrated in extracted supplement form as provided in Ellagic Insurance Formula. Approximately 200 mg of Green tea catechins in this formula corresponds to the amount of catechins found in 5-8 cups of Green tea.

Selected References

Ahmad N et al. Green tea polyphenols and cancer: biologic mechanisms and practical implications. Nutr Rev 57(3): 78-83, 1999.

Brown MD. Green tea (Camellia sinensis) extract and its possible role in the prevention of cancer. Altern Med Rev 4(5): 360-370, 1999.

Bushman JL. Green tea and cancer in humans: a review of the literature. Nutr Cancer 31(3): 151-159, 1998.

Chen et al. Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts. Cancer Letters 129: 173-179, 1998.

Dulloo AG et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h expenditure and fat oxidation in humans. Am J Clin Nutr 70: 1040- 1045, 1999.

Gupta S et al. Prostate cancer chemoprevention by green tea. Semin Urol Oncol 17(2): 70-76, 1999.

Imai K et al. Cancer-preventive effects of drinking green tea among a Japanese population. Prev Med 26(6):769-75, 1997.

Ji HT et al. Green tea consumption and the risk of pancreatic and colorectal cancer. Int J Can 7; 255-258, 1997.

Kono S et al. Relation of green tea consumption to serum lipids and lipoproteins in Japanese men. J Epidemiol 6(3):128-33, 1996. Lin JK et al Cancer chemoprevention by tea polyphenols. Proc Natl Sci Counc Repub China B 24(1):1-13, 2000.

Mukhtar H et al. Tea polyphenols: prevention of cancer and optimizing health. Am J Clin Nutr 71(6 Suppl):1698S-702S, 2000.

Nakayama M et al. Inhibition of the infectivity of influenza virus by tea polyphenols. Antiviral Res 21: 289-299, 1993.

Picard D. The biochemistry of green tea polyphenols and their potential application in human skin cancer. Alt Med Rev 1: 31-42, 1996.

Sasazuki S et al. Relation between green tea consumption and the severity of coronary atherosclerosis among Japanese men and women. Ann Epidemiol 10(6):401-8, 2000.

Stich HF. Teas and tea components as inhibitors of carcinogen formation in model systems and man. Prevent Med 21: 377-384, 1992.

Yang CS et al. Tea and tea polyphenols inhibit cell hyperproliferation, lung tumorigenesis, and tumor progression. Exp Lung Res 24(4):629-39, 1998.

Weisburger JH. Mechanisms of action of antioxidants as exemplified in vegetables, tomatoes, and tea. Food Chem Toxicol 37(9-10): 943-948, 1999.

Weisburger JH. Tea and health: the underlying mechanisms. Proc Soc Exp Biol Med 2200(4): 271-275, 1999.