It became a popular beverage first in China and then in Japan, then much later in the 1600s, all over Europe and America. T ea comes from the plant camellia sinensis, an evergreen shrub with white blossoms that thrives in tropical and semi-tropical climates. What distinguishes them is their method of manufacture. Annually approximately 2.5 million metro tons of dried tea leaves are procured. This better preserves the natural active substances of the leaf.
Green tea contains polyphenols.
Most of the green tea polyphenols are flavonols, commonly known as catechins. Caffeine, theobromine, and theophylline, the principal alkaloids, account for the other constituents of green tea, besides phenolic acids such gallic acids and characteristic amino acids such as theanine. P olyphenols are thought to be responsible for tea s anti-oxidant effects, as well as for inhibiting cellular replication and adhesion. A ccording to Hirota Fujiki, a chemist at the National Cancer Center Research Institute in Tokyo, antioxidants have some ability to halt enzymes that produce carcinogens and can destroy molecules called free radicals that could otherwise attack DNA and disrupt normal cell processes. P urdue University researchers Dorothy Morre and D. James Morre found that epigallocatechin gallate, EGCg, a compound found in green tea, inhibits an enzyme required for cancer cell growth and can kill cultured cancer cells with no ill effect on healthy cells.