Tea and circulating estrogen levels in postmenopausal Chinese women in Singapore

The role of tea in the etiology of breast cancer is con-troversial. We recently provided the first set of human evidence that breast cancer risk is significantly inversely associated with tea intake, largely confined to intake of green tea. Since black tea and green tea possess compar-able levels of the total tea polyphenols that possess anti-oxidative activities, reasons for the paradoxical effects of green tea and black tea on breast cancer protection are not apparent. Some limited evidence suggests that green tea may have downregulatory effects on circulating sex-steroid hormones, whereas black tea may have upregu-latory effects. We therefore, investigated the relationship between tea intake, and plasma estrogen and androste-nedione levels in a cross-sectional study of healthy post-menopausal Chinese women in Singapore. In this grou