According to Zen Buddhist legend, the first patriarch, Bodhidharma, around the sixth-century A. D., trying to keep himself awake, cut off his eyelids. After falling to the ground, they grew up as tea plants. Ever since, tea has been used to fend off sleep and clear the soul. Historians believe that tea originated about five thousand years ago in The Pamirs between India and China. In Tibet, it is still possible to find tea trees more than a thousand years old and 100 feet tall.

Commercial tea trees (Camellia senesis) are trimmed often, and so are small bushy plants about 2-3 feet high. Tea leaves are picked 3-4 times between spring and fall every year. Green tea is produced from the leaves that are picked and heated quickly in a pan or by hot steam to kill microorganisms and stop enzymatic action to prevent fermentation. Other tea products are normally fermented to enhance taste and flavor. Oolong tea, often served in Chinese restaurants, is 25-50% fermented, whereas black or red teas are over 80% fermented.

In oriental culture, it has been widely believed for a long time that tea has medicinal efficacy in preventing and treatment of many diseases. Drinking tea is often related to longevity. According to Chinese history, Emperor Sin-Non found, more than three thousand years ago, that a daily cup of tea could dissolve many poisons in the body. Scientific and medical evaluation of tea, however, started only very recently. Early epidemiological studies yielded inconclusive evidence whether tea is medically beneficial. In fact, some reports warned that consumption of tea may by linked to cancer of esophagus and stomach. These observations have not been confirmed in other studies. Part of the difficulty in making a clear evaluation of links between tea and health lie in the use of different varieties of tea products and confounding roles of other dietary and non dietary components. An increase in esophageal cancer due to drinking tea has been positively related to the high temperature of the tea rather the components of tea.

Recently, numerous scientific studies support a preventive role for tea in cancer. Epidemiological studies linked green tea use to a lower rate of esophageal cancer. In Japan, stomach cancer incidence in tea growing districts is about one half of that in districts not producing tea. In experimental animals, the incidence of cancer induced by various chemical carcinogens (including some of the carcinogens in cigarette smoke) in different organs (skin, stomach, liver, lung, breast, duodenum, and colon) can be significantly reduced by allowing animals the ingest green tea. Rats given green tea for several months developed less skin cancer when they were irradiated by ultra violet light. Other human and animal studies, yet to be confirmed, indicated that long-term use of green tea may reduce the cholesterol level and increase the high density lipoprotein (HDL) cholesterol level in blood. One Japanese report also indicated that the incidence of stroke was 2-3 times lower in those who drank larger quantities of green tea. Components of green tea also have anti-inflammatory effects and anti-bacterial activity, suggesting their possible use in skin care and prevention of dental caries.

Understanding the molecular mechanism of carcinogenesis may provide a rational judgment of how green tea components may be beneficial in prevention and therapy of cancer and other diseases. Two major components of green tea are epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) which represents about 30% of the dry weight of a hot water extract of green tea. EGCG appears to be the major anti-tumorigenic substance in green tea. There are indications that these green tea compounds can interfere with tumor promotion by TPA (a phobol ester tumor promoter) in carcinogen-induced tumors. Other studies have indicated that some oncogene functions may be altered.

We have found that both ECG and EGCG can prevent activation of male hormones which is needed for development of prostate cancer, benign prostatic hyperplasia, baldness, and acne. Therefore, these green tea compounds may be effective in treating some of these male hormone-related abnormalities in human. In fact, we have shown that the growth of human prostate tumors in mice can be prevented and actually suppressed by administration of EGCG. The effect can be observed within 2 to 4 weeks. Similar EGCG-dependent suppression was also found with human breast tumors growing in mice.

Since ECG and EGCG can be oxidized by air quickly and its anti-tumorigenic activity destroyed, some care should be exercised in the storage of tea and making tea beverage. Following guidelines may be helpful: (a) buy green tea picked within a year, (b) store tea leaves in a refrigerator, (c) put 2-3 tablespoons of green tea in a small 8-12 oz thermos, (d) add hot water to the top of the thermos to exclude air, (e) cover tight and allow to stand for 20-30 minutes, (f) pour the drink into a cup and add a small piece of ice, and drink immediately. Never drink very hot tea and never leave tea on the table for a long time before drinking. An alternative method, which is highly recommended, is to make your own green tea powder in a coffee bean grinder, then put green tea powder into anything you want to eat or drink, including meat, fish, sandwiches, hamburgers, pizza, salads, vegetables, soups, milk, and ice cream. Blending with fruit and vegetable juice may make it easier to consume a large amount of green tea. Eating dried green tea leave products is also a good idea.
A final note: --- the amount of caffeine in one cup of green tea is about one quarter of that in one cup of coffee so you can limit your consumption of tea to whatever level allows you to get a good nightˇ¦s rest.

*(1). For daily use, 3-6 grams dried green tea (1-2 table spoons) may be appropriate. For serious problems, 15-30 grams dried green tea (5-10 table spoons) may be needed. Since the body may gradually adapt to and destroy green tea EGCG, it may be a good idea to take green tea intermittently, on for 2-3 weeks and off for 1-2 weeks, especially for a heavy douser.

*(2). For updated review, see: S. Liao, Y. H. Kao, and R. A. Hiipakka (2001) ˇ§Green Tea: Biochemical and Biological Basis for Health and Benefitsˇ¨ in ˇ§Vitamins and Hormonesˇ¨ Volume 26, pages 1-94. .