Most of the studies of the effect of the green tea have been focused on its cancer-causing and cancer-protecting aspects. Green tea polyphenols are potent antioxidant compounds. They are more potent antioxidants than vitamin E and vitamin C.
Green tea may also increase the activity of the antioxidant enzyme. A number of animal studies have shown that green tea polyphenols may offer significant protection from cancer. It is believed that they do so by blocking the formation of cancer-causing compounds such as nitrosamines, suppressing the activation of carcinogens, and detoxifying or trapping cancer causing agents.
Green tea is believed to have the greatest effect on cancers of the gastrointestinal tract such as stomach, small intestine, pancreas, and colon; lung cancer; and estrogen related cancers including most breast cancers.
It is interesting to note that green tea prevents cancer, whereas black tea increases the risk of certain cancers such as cancer of the rectum, gallbladder, and endometrium.
Description:
All teas (green. black, and oolong) are derived from the same tea plant, Camellia sinensis. The difference is in how the plucked leaves are prepared.
The tea plant has long been cultivated in China. It is an evergreen shrub or tree that can grow to a height of 30 feet, but is usually maintained at a height of 2 to 3 feet by regular pruning. The hairy leaves of the tea plant are used both as a social and medicinal beverage. The parts used are the leaf bud and the two adjacent young leaves together with the stem, broken between the second and the third leaf. Older leaves are considered inferior in quality.
Green tea, unlike black and oolong tea, is not fermented, so the active constituents remain unaltered in the herb. It is produced by lightly steaming the fresh cut leaf. Green tea is very high in polyphenols with potent antioxidant and anticancer properties.
Dosage:
Much of the research documenting the health benefits of green tea is based on the amount of green tea typically drunk in Asian countries-about three cups per day (providing 240-320 mg of polyphenols).
To brew green tea, 1 teaspoon of green tea leaves are combined with 250 ml (1 cup) of boiling water and steeped for three minutes. Tablets and capsules containing standardized extracts of polyphenols, particularly EGCG, are available; some are decaffeinated and provide up to 97% polyphenol content-which is equivalent to drinking four cups of tea.
Safety:
Green tea is extremely safe. The most common adverse effect reported from consuming large amounts of green tea is insomnia, anxiety, and other symptoms caused by the caffeine content in the herb.
