Benefits of Tea
Tea, particularly green tea, has many health benefits. Tea leaves contain about 25 percent protein, 6 percent fat, 40 percent carbohydrate, 5 percent ash, 3 percent caffeine, and 13 percent tannin; other main ingredients include quercetin, flavonoids, theophylline, volatile oil, silicic acid, fluoridate, vitamins B, C, P, etc.; but the primary constituents of interest are the polyphenols, particularly the catechin called epigallocatechin gallate (EGCG). Polyphenols are believed to be responsible for most of tea's roles in promoting good health. Tea contains only four calories per cup when consumed without added ingredients.
Green tea contains abundant antioxidants "polyphenols," which can unify with the free radicals in our body, preventing the free radicals from attaching onto the normal cells, causing destruction to the cells. This function of polyphenols has therefore anti-cancer and delaying aging capabilities to our body.
Polyphenols in teas are similar to other phytochemicals found in many foods like broccoli and carrots, which are much higher in tea up to 36% of dry weight. Polyphenols include many chemical compounds. The most beneficial polyphenols are catechins which are found more in green tea but also in other teas. The most effective catechins found so far are epigallocatechin gallate (EGCG) and epigallocatechin (EGC).
Free radicals are produced when we breathe. 98% of oxygen we breathe in are used in generating energy; however, 2% are turned into free radicals. Therefore, the existence of free radicals in our body is unavoidable. In addition, ultraviolet ray, radiation, smoking, greasy foods, exhaust fumes, etc., all can cause excessive free radicals generated in our body. When we age or are lacking in exercise, the antioxidant that naturally produced in our body would be reduced, letting free radicals a freer hand, so to speak, to destroy the normal cells in our body, causing senility, even cancer. Old age and lack of exercise could also induce skin melanin and bad cholesterols to accumulate, bringing about age-spots and atherosclerosis. To delay aging, we therefore have to depend on some anti-oxidant foods.
The International Journal of Oncology reported in 2001 that polyphenols could prevent the activities of urokinase, the main culprit of the formation of tumor and the proliferation of cancer, thus reducing the chance of getting cancer.
The latest study ("The Antifolate Activity of Tea Catechins," published in Cancer Research 65 (2005), pp. 2059-2064) carried out by Roger Thorneley, a British researcher, and three other Spanish experts showed the polyphenol epigallocatechin gallate (EGCG) taken from green tea leaves inhibits cancer cell growth. The effect was seen even at low concentrations, equivalent to drinking two or three cups of green tea a day. However, the study also found high concentrations of the chemical may increase the risk of birth defects.
Green tea has also the effect of preventing Parkinson's Disease. Since free radicals could cause the neurotransmitter dopamine in the large cell mass substantia nigra in the brain to slowly self-destruct, turning the condition into Parkinson's Disease. The substantive EGCG in green tea, as we know, could neutralize free radicals; therefore, by and large, has the effect of preventing Parkinson's Disease.
A Japanese medical researcher Kuzushige Kawai and colleagues from the University of Tokyo has reported that EGCG could block the envelope of HIV (AIDS virus). EGCG in green tea could also cause the pre-adipocyte to self-destruct, which makes green tea a very effective weight-control beverage. Scientists at the University of Chicago have found that green tea caused rats to lose up to 21% of their body weight. Rats injected with a green tea extract lost their appetites and consumed up to 60% less food after seven days of daily injections.
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