Advance Access publication July 31, 2008 Green tea intake, MTHFR/TYMS genotype and breast cancer risk: the Singapore Chinese Health Study

The tea polyphenol (2)-epigallocatechin-3-gallate (EGCG) has been reported to act as a cancer preventive agent through folate pathway inhibition in experimental studies. We hypothesized that if folate pathway inhibition is the mechanism of cancer preventive activities of EGCG, then the protective effect against breast can-cer would be stronger among women with low dietary folate in-take and the high-activity methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TYMS) genotypes. In a nested case–control study of 380 women with incident breast cancer and 662 controls within the Singapore Chinese Health Study, we found no association between either green tea intake or gene polymorphisms of MTHFR (C677T and A1298C) and TYMS (1494 ins/del) and breast cancer risk. However, among women with low folate intake (<133.4 mg/day), weekly/daily green tea intake was inversely associated with breast cancer risk com