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Life Extension Magazine

LE Magazine November 2005
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Can Green Tea Protect Against Prostate Cancer?

By Coulson K. Duerksen

Green Tea and Cancer Prevention

Numerous animal and human cell studies suggest that green tea catechins may act as powerful inhibitors of cancer,17,18 particularly colon, rectal, and prostate cancers,19,20 as well as cancers of the lung, stomach, and kidney.21 Green tea catechins appear to be effective chemopreventive agents against a variety of carcinogens.

In addition to laboratory studies, population studies tracking the health of large groups of people who drink tea in abundance demonstrate the cancer-preventive benefits of green tea. Population studies have found reduced cancer rates in Asian countries where green tea is a dietary staple.22,23 In one Asian study, tea drinkers were about half as likely to develop stomach or esophageal cancer as men who drank little tea, even after adjusting for smoking and other health and dietary factors24 Japanese men, who commonly drink four to six cups of green tea daily, also have significantly lower rates of cancer incidence and mortality than Westerners.18,25

FACTS ABOUT TEA

• All teas (green, black, and oolong) are derived from the same plant, Camellia sinensis. They differ in how the plucked leaves are prepared.
• Unlike black and oolong tea, green tea is not fermented, so the active constituents remain unaltered in the herb.
• Green tea contains abundant antioxidants and may be as important as fruits and vegetables to your daily nutritional intake.30
• To get an adequate amount of tea polyphenols, you may need 3-10 cups of green tea daily or 300-1200 mg of green tea extract in capsule form.

It has long been noted that the lung cancer rate in Japan is one of the lowest in the world, despite that nation’s high rate of smoking. Data from a case-controlled study conducted in Okinawa, Japan, from 1988 to 1991 showed that the greater the intake of Okinawa tea (a partially fermented tea), the smaller the risk of squamous cell lung cancer, particularly in women.26 These findings suggest that tea consumption has a protective effect against lung cancer in humans.

Another interesting fact relating to green tea consumption is that the cancer mortality rate in Shizuoka Prefecture, located in central Japan, is much lower than the Japanese average. As it turns out, green tea intake is even more habitual in the Shizuoka Prefecture than in other areas of Japan.27

Conclusion

FDA regulators believe the evidence that green tea prevents cancer is insufficient to merit a limited health claim, and that, based on the “limited” research available, green tea is highly unlikely to reduce the risk of prostate or any other type of cancer.

Given the limited information available concerning the biological processes that lead to the development of prostate cancer, it is wise to examine all possible prevention strategies. While a larger, confirmatory study is needed, the Bettuzzi study shows that green tea catechins may be an excellent prophylactic agent against prostate cancer in men at high risk for the disease.4

Most modern medicines used to treat cancer have serious side effects, high costs, and other associated risks. Green tea, on the other hand, is safe and widely available as a beverage and a nutritional supplement. Furthermore, growing scientific evidence suggests that green tea is effective in preventing many diseases associated with aging, including prostate and other cancers.

References

1. Siddiqui IA, Afaq F, Adhami VM, Ahmad N, Mukhtar H. Antioxidants of the beverage tea in promotion of human health. Antioxid Redox Signal. 2004 Jun;6(3):571-82.

2. Beliveau R, Gingras D. Green tea: prevention and treatment of cancer by nutraceuticals. Lancet. 2004 Sep 18;364(9439):1021-2.

3. Available at: http://www.cfsan.fda.gov/~dms/qhc-gtea.html. Accessed August 12, 2005.

4. Bettuzzi S. School of Medicine, University of Parma, Italy; Jay Brooks, MD, chairman, hematology/oncology, Ochsner Clinic Foundation Hospital, New Orleans; April 19, 2005, presentation, American Association for Cancer Research, annual meeting, Anaheim, CA.

5. Klein EA, Thompson IM. Update on chemoprevention of prostate cancer. Curr Opin Urol. 2004 May;14(3):143-9.

6. Wright SC, Zhong J, Larrick JW. Inhibition of apoptosis as a mechanism of tumor promotion. FASEB J. 1994 Jun;8(9):654-60.

7. Liao S, Hiipakka RA. Selective inhibition of steroid 5 alpha-reductase isozymes by tea epicatechin-3-gallate and epigallocatechin-3-gallate. Biochem Biophys Res Commun. 1995 Sep 25;214(3):833-8.

8. Cooper R, Morre DJ, Morre DM. Medicinal benefits of green tea: part I. Review of noncancer health benefits. J Altern Complement Med. 2005 Jun;11(3):521-8.

9. Hong J, Smith TJ, Ho CT, August DA, Yang CS. Effects of purified green and black tea polyphenols on cyclooxygenase- and lipoxygenase-dependent metabolism of arachidonic acid in human colon mucosa and colon tumor tissues. Biochem Pharmacol. 2001 Nov 1;62(9):1175-83.

10. Sazuka M, Imazawa H, Shoji Y, et al. Inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins. Biosci Biotechnol Biochem. 1997 Sep;61(9):1504-6.

11. Zhao BL, Li XJ, He RG, Cheng SJ, Xin WJ. Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals. Cell Biophys. 1989 Apr;14(2):175-85.

12. Available at: http://www.aicr.org/press/pubsearchdetail.lasso?index=2057. Accessed August 12, 2005.

13. Oguri A, Suda M, Totsuka Y, Sugimura T, Wakabayashi K. Inhibitory effects of antioxidants on formation of heterocyclic amines. Mutat Res. 1998 Jun 18;402(1-2):237-45.

14. Zhu BT, Taneja N, Loder DP, Balentine DA, Conney AH. Effects of tea polyphenols and flavonoids on liver microsomal glucuronidation of estradiol and estrone. J Steroid Biochem Mol Biol. 1998 Feb;64(3-4):207-15.

15. Lin YL, Cheng CY, Lin YP, Lau YW, Juan IM, Lin JK. Hypolipidemic effect of green tea leaves through induction of antioxidant and phase II enzymes including superoxide dismutase, catalase, and glutathione S-transferase in rats. J Agric Food Chem. 1998;46(5):1893-99.

16. Navarro-Peran E, Cabezas-Herrera J, Garcia-Canovas F, et al. The antifolate activity of tea catechins. Cancer Res. 2005 Mar 15;65(6):2059-64.

17. Chen D, Daniel KG, Kuhn DJ, et al. Green tea and tea polyphenols in cancer prevention. Front Biosci. 2004 Sep 1;9:2618-31.

18. Kuroda Y, Hara Y. Antimutagenic and anticarcinogenic activity of tea polyphenols. Mutat Res. 1999 Jan;436(1):69-97.

19. Saleem M, Adhami VM, Siddiqui IA, Mukhtar H. Tea beverage in chemoprevention of prostate cancer: a mini-review. Nutr Cancer. 2003;47(1):13-23.

20. Ji BT, Chow WH, Hsing AW, et al. Green tea consumption and the risk of pancreatic and colorectal cancers. Int J Cancer. 1997 Jan 27;70(3):255-8.

21. Kinlen LJ, Willows AN, Goldblatt P, Yudkin J. Tea consumption and cancer. Br J Cancer. 1988 Sep;58(3):397-401.

22. Fujiki H, Suganuma M, Okabe S, et al. Cancer inhibition by green tea. Mutat Res. 1998 Jun 18;402(1-2):307-10.

23. Suganuma M, Okabe S, Sueoka N, et al. Green tea and cancer chemoprevention. Mutat Res. 1999 Jul 16;428(1-2):339-44.

24. Hu J, Nyren O, Wolk A, et al. Risk factors for oesophageal cancer in northeast China. Int J Cancer. 1994 Apr 1;57(1):38-46.

25. Nakachi K, Eguchi H, Imai K. Can teatime increase one’s lifetime? Ageing Res Rev. 2003 Jan;2(1):1-10.

26. Ohno Y, Wakai K, Genka K, et al. Tea consumption and lung cancer risk: a case-control study in Okinawa, Japan. Jpn J Cancer Res. 1995 Nov;86(11):1027-34.

27. Oguni I, Cheng SJ, Lin PZ, Hara Y. Protection against cancer risk by Japanese green tea (abstract). Prev Med. 1992 May;21(3):332.

28. Yu H, Oho T, Xu LX. Effects of several tea components on acid resistance of human tooth enamel. J Dent. 1995 Apr;23(2):101-5.

29. Westerterp-Plantenga MS, Lejeune MP, Kovacs EM. Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Obes Res. 2005 Jul;13(7):1195-204.

30. Prior RL, Cao G. Antioxidant capacity and polyphenolic components of teas: implications for altering in vivo antioxidant status. Proc Soc Exp Biol Med. 1999 Apr;220(4):255-61.