Tea is second only to water as the world's most commonly consumed beverage, according to Dr. Craig Schneider of the Maine Medical Center. Tea is also one of the world's most commonly researched beverages, due to scientific interest in the potential health benefits of green tea. Green tea is high in polyphenols, substances that have been studied for their potential disease-fighting applications, including cancer prevention and treatment.
Green Tea
Black, oolong and green teas are made from the leaves of the Camellia sinensis plant. The three teas differ in the way the leaves are processed. Green tea is harvested, steamed and dried; oolong tea is partially fermented; and black tea is fully fermented. Green tea retains its high concentration of polyphenols, but fermentation depletes polyphenols from oolong and black tea.
Polyphenols
Polyphenols are powerful antioxidants. They neutralize free radicals, which are unstable molecules that cause cell damage, accelerate aging and increase your risk of certain diseases. You're exposed to free radicals daily via pollution and radiation. According to the University of Maryland Medical Center, polyphenols found in green tea may help decrease your risk of certain forms of cancer. Epigallocatechin gallate is the most widely studied polyphenol found in green tea.
Green Tea and Cancer
According to the American Cancer Society, laboratory studies have revealed that green tea extracts may inhibit blood supply to cancer cells, but efforts to demonstrate green tea's cancer-fighting results in humans have yielded mixed results. A study published in the Journal of the American Medical Association in 2006 found that green tea consumption was associated with decreased cardiovascular disease mortality, but that cancer rates were unrelated to green tea consumption. That study, conducted by Dr. Shinichi Kuriyama of the Tohoku University Graduate School of Medicine in Japan, examined the green tea consumption of 40,000 Japanese adults over a 10-year period.
Conclusions
The bottom line is that the link between green tea and cancer has not been conclusively confirmed. Research into the connection between green tea and cancer risk remains promising but inconclusive. Evidence suggests that green tea may help ward off cancers of the gastrointestinal tract, breast and prostate gland, according to Dr. Schneider. More research is needed to clarify the potential role of green tea extract as an adjunct to cancer therapy.
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