First, they can shut off the formation of carcinogens, secondly, they turn up the body's natural detoxification defenses, and finally, they suppress cancer promotion. Green tea polyphenols seem to increase the actions of a number of our detoxification enzymes, including catalase and Glutathione per oxide. Polyphenols are most abundant in green tea, but are also present in black tea. Both teas are made from the leaves of the same plant, camellia sinensis, but each is processed differently, giving different poly phenol contents. When speaking of a tea's energetic effects, we are referring to how it affects chi.
Chinese teas are slightly laxative, or help clear phlegm without irritating the nervous system.
Coffee can make you nervous but tea clears your head while it stimulates digestion. Which teas are best for you depends on your needs. Oolong is a gem of teas that is actually semi fermented and lies somewhere between green and black tea. It has less caffeine than either black tea or coffee. It also has been touted in China as a cancer preventative because of its acids and flavinoids.