Green Tea Can Prevent Cancer
Men who drink five or more cups of green tea a day might reduce the risk of advanced prostate cancer by up to 50 percent compared to those who drink one cup a day, according to a study by researchers at Japan’s National Cancer Center. “This does not mean that people who drink green tea are guaranteed to have reduced risk of advanced prostate cancer,” said Norie Kurahashi, a scientist who took part in the study. ” But the study does point to the hope that green tea reduces the risk of advanced prostate cancer.”
Purdue University researchers Dorothy Morre and D. James Morre found that EGCg, a compound in green tea, inhibits an enzyme required for cancer cell growth and can kill cultured cancer cells with no ill effect on healthy cells. The findings offer the first scientific evidence to explain precisely how this compound works within a cell to ward off cancer. The results were presented this month at the 38th annual meeting of the American Society for Cell Biology in San Francisco.
“Our research shows that green tea leaves are rich in this anti-cancer compound, with concentrations high enough to induce anti-cancer effects in the body,” says Dorothy Morre, professor of foods and nutrition at Purdue.
The findings suggest that drinking more than four cups of green tea a day could provide enough of the active compound to slow and prevent the growth of cancer cells, she says.
Although all teas come from the same botanical source, green tea differs from black tea or other teas because of the way the tea leaves are processed after they are picked. For black tea, freshly picked leaves are “withered” indoors and allowed to oxidize. With green tea, the leaves are not oxidized, but are steamed and parched to better preserve the natural active substances of the leaf.
Morre and her husband, who is the Dow Distinguished Professor of Medicinal Chemistry and Molecular Pharmacology at Purdue, show in their study how green tea interacts with an enzyme on the surface of many types of cancer cells including breast, prostate, colon and neuroblastoma. This enzyme, called quinol oxidase, or NOX, helps carry out several functions on the cell surface and is required for growth in both normal and cancerous cells.
“Normal cells express the NOX enzyme only when they are dividing in response to growth hormone signals,” Dorothy Morre says. “In contrast, cancer cells have somehow gained the ability to express NOX activity at all times.” This overactive form of NOX, known as NOX - for tumor-associated NOX - has long been assumed to be vital for the growth of cancer cells, because drugs that inhibit NOX activity also block tumor cell growth in culture.
After hearing a researcher discuss green tea’s anti-cancer potential on a television show, the couple set out to investigate whether tea infusions — made when the compounds of tea leaves leach into hot water — would have an effect on NOX enzyme activity.
Tags: anti-cancer, cancer cells, Medicinal Chemistry, Pharmacology