The Secrets of Green Tea

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An Ounce of Prevention: Green Tea Fights Cancer Like Chemo.

An Ounce of Prevention: Green Tea Fights Cancer Like Chemo

For the first time, scientists have shown how green tea works to fight cancer. Researchers at the John Innes Centre in Norwich, U.K., and the University of Murcia in Spain found that a substance in green tea called epigallocatechin gallate, or EGCG, appears to prevent cancer cells from developing in much the same way as an established chemotherapy drug, methotrexate.

Both methotrexate and EGCG bind to an enzyme that triggers tumor cells to reproduce. Because EGCG may cause less damage to healthy cells than methotrexate does, it holds promise as the source of a future cancer drug. The downside: women who drink lots of green tea around the time of conception or during pregnancy may have a higher risk of bearing children with birth defects, the researchers say. This is because the cancer-fighting EGCG also lowers the effectiveness of folic acid, a B vitamin that helps prevent neural tube disorders such as spina bifida.

Another risk: some scientists suggest that taking supplements containing large concentrations of green tea extracts — equivalent to drinking hundreds of cups of green tea a day — might have the opposite effect, namely helping some tumors grow.

Nevertheless, drinking green tea in moderation appears to be good for you. Just check with your doctor before consuming large amounts of it — especially in supplement form or if you’re pregnant.

The most recent study, done at Purdue University and presented at a meeting of the American Society for Cell Biology, discovered another major mechanism. The authors, the husband and wife team of Dorothy and James Morre, claim that the main tumor-inhibitory mechanism of green tea may stem from its ability to interfere with the enzyme quinol oxidase, generally referred to as NOX. This enzyme is required for growth by both normal and malignant cells. While normal cells express NOX only when dividing, tumor cells express it all the time. The tumor form of the enzyme is called t-NOX, or tumor-associated NOX. Drugs that inhibit tNOX also inhibit tumor growth.

Green Tea May Also Do Wonders for the Brain
SOURCE: Kuriyama, S. The American Journal of Clinical Nutrition, Feb. 1, 2006; vol 83: pp 355-361.

Elders who drink green tea regularly may have sharper minds than those who don't drink green tea. The finding comes from a Japanese study published in The American Journal of Clinical Nutrition.

The study included about 1,000 Japanese people aged 70 and older. Participants took tests of mental status including memory, orientation, ability to follow commands, and attention. They also told the researchers how often they drank beverages including green tea.

Those who reported drinking the most green tea were least likely to show cognitive impairment, based on their test scores, write Shinichi Kuriyama, MD, PhD, and colleagues.

Kuriyama works in the department of public health and forensic medicine at Tohoku University's medical school in Sendai, Japan.

Drinking at least two daily cups of green tea was tied to the lowest risk of cognitive impairment in Kuriyama's study.

"To our knowledge, this is the first study to examine the association between consumption of green tea and cognitive function in humans," Kuriyama's team writes.

They note that natural compounds in green tea -especially a chemical called EGCG (epigallocatechin-3-gallate) - have shown promise in experiments on brain diseases in animals.