The National Cancer Institue is researching the benefits of green tea.
Antioxidants found in green tea may reduce risks of certain types of cancer.
Long regarded in those cultures as an aid to good health, researchers now are studying tea for possible use in the prevention and treatment of a variety of cancers.
To become stable, oxidants steal electrons from other molecules and, in the process, damage cell proteins and genetic material.
With the additional process of allowing the leaves to ferment and oxidize, black tea is produced.
Possibly because it is less processed, green tea contains higher levels of antioxidants than black tea.
Although tea is consumed in a variety of ways and varies in its chemical makeup, one study showed steeping either green or black tea for about five minutes released over 80 percent of its catechins.
In the laboratory, studies have shown tea catechins act as powerful inhibitors of cancer growth in several ways: They scavenge oxidants before cell injuries occur, reduce the incidence and size of chemically induced tumors, and inhibit the growth of tumor cells.
In studies of liver, skin and stomach cancer, chemically induced tumors were shown to decrease in size in mice that were fed green and black tea (1, 2).
Some epidemiological studies comparing tea drinkers to non-tea drinkers support the claim that drinking tea prevents cancer; others do not.
National Cancer Institute (NCI) researchers are also investigating the therapeutic use of green tea.
One recently completed but unpublished NCI trial studied the antitumor effect of green tea among prostate cancer patients.
For example, one is investigating the protective effects of a pill form of green tea against sun-induced skin damage while another explores the topical application of green tea in shrinking precancerous skin changes.