good stuff on green tea

The Benefits of Green Tea
By JP Saleeby, MD

Green Tea: Three glasses a day keeps cancer away

Consumed by millions in the Far East we are just beginning to get used to seeing this unfermented cousin of the black tea most Westerners are accustomed to drinking. For hundreds of years this very popular drink has been praised for its health benefits, which are now backed up by recent scientific study. Breast and prostate cancer are among the leading causes of cancer death in the US. Even with our advances in medicine these two types of malignancies claim 200,000 new victims annually and up to 50,000 deaths per year. Because of the latency in development of these two particular cancers there is opportunity for prevention. Further more, reduction in the risk of recurrence if one is unlucky enough to be stricken with them in the first place also applies. While there are several treatments for these cancers, prevention would be a person's wiser choice. Since it can take 20 to 40 years to develop breast and prostate cancer, anyone wishing to prevent these cancers would search for something that was safe and effective for long-term use to radically diminish the chances of acquiring these cancers.

Green tea, a very popular beverage in the East has been studied as a chemopreventive agent against cancers. This beverage, popular for over 4000 years and consumed in quantity only second to water, has stood the test of time so to speak. It is has been around long enough and consumed by millions of people to judge its safety and efficacy. Green tea comes from the evergreen Camellia sinensis and the dried leaf is infused with hot water to yield the beverage. Green tea has been scientifically studied and shown to diminish primary occurrence as well as recurrence of cancers of the colon, ovary, breast and prostate. There are certain flavonoids and polyphenols in the tea that once absorbed have potent antioxidant properties. This is just one of many mechanisms of action on inhibiting cancer. Studies have shown that these flavanoids and polyphenols are very well absorbed when taken orally either in the form of a drink or in capsules. Unlike pharmaceutical agents that act on a single target when fighting cancer, the green tea polyphenols harbor a multidimensionality against tumorigenesis (tumor formation).

In mice, Interluken-2 deficient specimens prone to cancer survived when given green tea polyphenols which were found to lower interferon-gamma and tumor necrosis factor-alpha. In human studies, there is overwhelming evidence that green tea reduces incidence of breast and prostate cancer as well as reduces recurrence in those treated for these cancers. Epidemiological studies have found a two-fold reduction in breast cancer in women who consistently consume green tea. Another study involving men found the relative risk for prostate cancer nearly one-fourth in those who drank at least three cups of green tea daily. This is big news for those at high risk or cancer survivors.

Although safer than most chemotherapeutic drugs, one has to be concerned about caffeine if they are sensitive (there are decaffeinated formulas available) and the possible interaction with the blood thinner warfarin, since green tea contains vitamin K in significant quantities. Vitamin K counteracts the effects of warfarin warranting careful monitoring for those taking this drug.

How much is enough? According to studies the average cup of green tea yield 50 to 150 mg of polyphenols depending on the amount of leaves used and the steeping time. Based on this at least three cups of (heartedly steeped) tea daily should provide 300 mg of the polyphenols. If you are not that big a tea-totter, you can also obtain this amount in a 400 mg (80% standardized extract) capsule. While higher doses seem to be very well tolerated the effect is dose dependent. Better protection against cancer is achieved obviously with higher doses, but one should consult a nutritionally minded physician or herbalist for guidance.

References:

Krochmal, R., Hardy, M. L., Green tea and breast and prostate cancer chemoprevention. Atlernative Medicine Alert, July 2004, 7:7:73-84.

Kohlmeier L, et al. Tea and cancer prevention: An evaluation of the epidemiological literature. Nutr Cancer 1997;27:1-13.

Varilek GW, et al. Green tea polyphenol extract attenuates inflammation in interleukin-2-deficient mine, a model of autoimmunity. J Nutr 2001;131:2034-2039.

Jatoi A, et al. A phase II trial of green tea in the treatment of patients with androgen independent metastatic prostate carcinoma. Cancer 2003;97:1442-1446.

Mittal A, et al. EGCG down-regulates telomerase in human breast carcinoma MCG-7 cells, leading to suppression of cell viability and induction of apoptosis. Int J Oncol 2004;24:703-710.