1 Green Tea Intake, ACE Gene Polymorphism and Breast Cancer Risk among Chinese Women in Singapore

D ow nloaded from 2 Experimental and epidemiological data have implicated a potential chemoprotective role of green tea polyphenols and a potential enhancing role of angiotensin II in the development of breast cancer in humans. Angiotensin II is converted from its precursor by angiotensin-converting enzyme (ACE). Women with the low-activity genotypes of the ACE gene had a reduced risk of breast cancer compared with those possessing the high-activity ACE genotypes. Experimental data showed that green tea polyphenols could inhibit angiotensin II-induced reactive oxygen species production. We reasoned that if this is one of the mechanisms by which green tea polyphenols protect against human breast cancer, then its effect should be more prominent among women possessing the high activity ACE genotype, than women with the low activity ACE genotype. In other words, we predict a stronger inverse green tea-breast cance