A powerful antioxidant ingredient in green tea kills human cancer cells in laboratory experiments. Tests of the ingredient, called epigallocatechin-3-gallate, showed it killed cancer cells in samples of skin, lymph system, and prostate tissue taken from both humans and mice while leaving healthy cells unharmed, report researchers from Case Western Reserve University in Cleveland, Ohio. Exactly how the tea ingredient works against cancer remains unclear. The compound leads to the programmed cell death, or apoptosis, of cancer cells.
It seems that somehow, through a cell-cell signaling pathway, it is communicated to the cancer cells that they better commit suicide or they'll be murdered. So cells make a decision and undergo apoptosis. At the highest dose of the green tea ingredient, nearly all cells were found to be in the latest stages of apoptosis. The researcher says the new findings add to previous test-tube studies showing that the tea ingredient prevented tumors in animal tissue. Dietary studies of tea consumption in people also suggest that green tea has some cancer preventive properties.
Some nutritional epidemiology studies have suggested that green tea consumption might be effective in the prevention of certain human cancers -- cancers of the bladder, prostate, esophagus, and stomach. One hospital in Shanghai reported that the recurrence of esophageal cancer was low in that part of the population that was drinking green tea. Green tea accounts for about 20% of global tea consumption, with black tea making up most of the rest. Tea consumption in the world is very high and ranks second to water consumption. The researcher notes that a cup of green tea contains between 100 and 200 milligrams of the anti-tumor ingredient.
Journal of the National Cancer Institute (1997;89(24):1881-1886)