Through millions of years of evolution, nature has created a fantastic array of plant and animal species, each with specific adaptations to survive.
These adaptations have resulted in an incalculable number of organic compounds unique to each living thing. As human beings have discovered, many plants contain pharmacologically active substances that can be used to treat a wide variety of medical conditions.
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Some notable examples include the antimalarial agent quinine, isolated in 1817 from the bark of the South American cinchona tree; penicillin, a substance produced by Penicillium notatum mold that was discovered in 1928; the cancer chemotherapy drug paclitaxel, which originally was derived from the Pacific yew tree; and opium.
The latest wonder plant may be tea, reportedly the second most widely consumed drink on the planet after water. Of the three types of tea—green, black, and oolong—the most hope is pinned on the green variety, which is made from the leaves of the Camellia sinensis plant. The leaves are steamed soon after plucking to stop certain enzymes from oxidizing. Green tea is a rich source of antioxidant compounds such as polyphenols.
A substantial and growing body of research has examined the potential health benefits of brewed green tea or green tea extracts. A PubMed search on “green tea” retrieved more than 2,700 papers (as of January 15), including review articles. One of the latest and best studies, conducted in Japan, examined prospectively whether drinking green tea is associated with a reduced risk of prostate cancer.
The researchers found that drinking five cups or more per day lowered the risk of advanced prostate cancer by 48% compared with drinking one cup or less per day. They observed no association with localized prostate cancer.
Previous studies looking at a potential link between tea consumption and prostate cancer risk have yielded inconsistent findings. The authors of the new report noted that subjects in some prior studies did not commonly drink green tea, but black tea. They also pointed out that almost all of the previous studies did not consider the effect of tea according to cancer stage.
Whether green tea is chemoprotective against prostate cancer remains to be determined, but the evidence gathered so far makes the possibility difficult to dismiss. And, frankly, given the absence of a downside to green tea, I plan to drink more of it.
