Green Tea May Protect
Against a Variety of Cancers


Green Tea May Protect
Women Against Stomach Cancer

If you are a woman, here’s another reason to drink green tea and/or to take green tea supplements. A just-published epidemiological study has found that Japanese women (but not men) who drink 5 of more cups of green tea per day are about 20% less likely to develop stomach cancer.1

The antioxidants found in green tea are thought to be anticarcinogenic and to protect against the deadly disease, owing in part to the role that certain bacteria play. These bacteria are fought by the components of green tea. While there have been inconsistent findings reported in prior studies, Dr. M. Inoue, at the National Cancer Center in Tokyo, decided to examine six older studies and the results of his analysis have just been reported in the journal, Gut.

Involving more than 219,000 men and women, 40 years or older, the span of the studies covered 7 to 11 years. Eighty percent of the subjects reported that they consumed 4–5 cups of green tea daily, with about 30% drinking 5 or more cups per day. In the follow-up stage, stomach cancer was developed in about 2,500 out of about 100,000 men and in about 1,000 of more than 118,000 women.

While the researchers found no linked benefit for the men, in women who drank 5 or more, compared with those drinking 1 or less cup of green tea, there was a 20% risk reduction of succumbing to stomach cancer. The results remained true even if the women smoked, although the results only considered stomach cancer. Of importance, the researchers noted that the reduced risk only applied to certain types of stomach cancer, specifically gastric cancer, but not to proximal gastric cancer.

1. Inoue M, Sasazuki S, Wakai K, Suzuki T, Matsuo K, Shimazu T, Tsuji I, Tanaka K, Mizoue T, Nagata C, Tamakoshi A, Sawada N, Tsugane S, and for the Research Group for the Development and Evaluation of Cancer Prevention Strategies in Japan. Green tea consumption and gastric cancer in Japanese: a pooled analysis of six cohort studies. Gut 2009;58(10):1323-32.

Green Tea Apt to Protect Both
Men and Women Against Liver Cancer

In another recent study, drinking green tea was associated with reduced risk for liver cancer in both men and women.2 Involving nearly 42,000 Japanese, 40 years or older, without a history of cancer when the study began, the researchers followed the frequency of green tea consumption for 9 years. The study was adjusted for age, alcohol drinking, smoking, coffee, vegetables, dairy products, fruit, fish, and soybean.

Among 325,947 accrued person-years (calculated as a product of the number of participants and the number of study-years), the researchers found the total incidence of liver cancer to be 247 cases. The more green tea consumed, the lower the incidence of cancer. There were risk reductions of up to 37% in men who consumed 5 or more cups of green tea per day, and up to 50% for women who drank as much. While there was no risk reduction for consuming less than 1 cup per day on average, both men and women experienced risk reduction for greater amounts, albeit less than at the highest level. These results make clear that drinking green tea is linked to a lower risk of liver cancer.

2. Ui A, Kuriyama S, Kakizaki M, Sone T, Nakaya N, Ohmori-Matsuda K, Hozawa A, Nishino Y, Tsuji I. Green tea consumption and the risk of liver cancer in Japan: The Ohsaki Cohort study. Cancer Causes Control 2009 Sep 19. [Epub ahead of print]

Green Tea Thought to
Reduce Endometrial Cancer

A meta-analysis of prior studies seeking to find the relationship of drinking green tea and endometrial cancer has also just been published.3 When the relative risk was calculated for those consuming varying amounts of green tea, an inverse correspondence between endometrial cancer and consumption was found for those consuming 2 cups per day, versus less than 1 cup per day. Drinking 2 cups lowered the risk of the cancer by 25%, indicating that there may be more protective effect from green tea than from black tea (as reported in other studies).

3. Tang NP, Li H, Qiu YL, Zhou GM, Ma J. Tea consumption and risk of endometrial cancer: a metaanalysis. Am J Obstet Gynecol 2009 Sep 19. [Epub ahead of print]

Green Tea’s EGCG May Be Its Most
Anti-Tumor Component

It is widely considered that the polyphenol (-)-epigallocatechin gallate (EGCG) appears to be green tea’s most powerful compound, when it comes to anticarcinogenic effects. Indeed, EGCG has demonstrated anti-tumor effects on various types of cancer cells. For the first time, a new paper shows that EGCG produces anti-tumor effects on gastrointestinal stromal tumors (these are among the most common tumors of the gastrointestinal tract; they are typically defined as tumors whose behavior is driven by mutations in the Kit gene).4 EGCG does this by suppressing cell proliferation and eventually inducing cell death.

Other cancers for which EGCG may be helpful include colon cancer,5 bladder cancer,6 leukemia,7 hematologic malignancies,8 lung cancer,9 breast cancer,10 prostate cancer.11

4. Chi HT, Vu HA, Iwasaki R, Thao LB, Hara Y, Taguchi T, Watanabe T, Sato Y. Green tea (-)-epigalocatechin-3-gallate inhibits KIT activity and causes caspase-dependent cell death in gastrointestinal stromal tumor including imatinib-resistant cells. Cancer Biol Ther 2009 Oct 22;8(20). [Epub ahead of print]
5. Larsen CA, Dashwood RH. Suppression of Met activation in human colon cancer cells treated with (-)-epigallocatechin-3-gallate: Minor role of hydrogen peroxide. Biochem Biophys Res Commun 2009 Sep 8. [Epub ahead of print]
6. Philips BJ, Coyle CH, Morrisroe SN, Chancellor MB, Yoshimura N. Induction of apoptosis in human bladder cancer cells by green tea catechins. Biomed Res 2009 Aug;30(4):207-15.
7. Okada N, Tanabe H, Tazoe H, Ishigami Y, Fukutomi R, Yasui K, Isemura M. Differentiation-associated alteration in sensitivity to apoptosis induced by (-)-epigallocatechin-3-O-gallate in HL-60 cells. Biomed Res 2009 Aug;30(4):201-6.
8. Naganuma T, Kuriyama S, Kakizaki M, Sone T, Nakaya N, Ohmori-Matsuda K, Hozawa A, Nishino Y, Tsuji I. Green tea consumption and hematologic malignancies in Japan: the Ohsaki study. Am J Epidemiol 2009 Sep 15;170(6):730-8.
9. Milligan SA, Burke P, Coleman DT, Bigelow RL, Steffan JJ, Carroll JL, Williams BJ, Cardelli JA. The green tea polyphenol EGCG potentiates the antiproliferative activity of c-Met and epidermal growth factor receptor inhibitors in non-small cell lung cancer cells. Clin Cancer Res 2009 Aug 1;15(15):4885-94.
10. McLarty J, Bigelow RL, Smith M, Elmajian D, Ankem M, Cardelli JA. Tea polyphenols decrease serum levels of prostate-specific antigen, hepatocyte growth factor, and vascular endothelial growth factor in prostate cancer patients and inhibit production of hepatocyte growth factor and vascular endothelial growth factor in vitro. Cancer Prev Res (Phila Pa) 2009 Jul;2(7):673-82.
11. Clement Y. Can green tea do that? A literature review of the clinical evidence. Prev Med 2009 May 22. [Epub ahead of print] PubMed PMID: 19465043.

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