Carcinogenesis Advance Access published online on January 20, 2005
Carcinogenesis, doi:10.1093/carcin/bgi028
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Preventive Medicine, University of Southern California Keck School of Medicine, Los Angeles, California 90089
* To whom correspondence should be addressed. The role of tea in the etiology of breast cancer is controversial. 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 comparable levels of the total tea polyphenols, which possess antioxidative 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 down-regulatory effects on circulating sex-steroid hormones, whereas black tea may have up-regulatory effects. We therefore investigated the relationship between tea intake and plasma estrogen and androstenedione levels in a cross-sectional study of healthy postmenopausal Chinese women in Singapore. In this group of 130 women, 84 were non-or irregular (less than once a week) tea drinkers, 27 were regular (weekly/daily) green-tea drinkers only, and 19 were regular (weekly/daily) black tea drinkers only. Relative to plasma estrone levels in non-or irregular tea drinkers (29.5 pg/ml), levels were 13% lower in regular green-tea drinkers (25.8 pg/ml) and 19% higher in regular black tea drinkers (35.0 pg/ml). These differences in estrone levels were statistically significant (P=0.03) even after adjusting for age, body mass index, intake of soy, and other covariates. A similar pattern of differences between tea intake and plasma levels of estradiol (P=0.08) and androstenedione (P=0.14) were found. In addition, the tea-estrogen associations were observed irrespective of the genotype of catechol-O-methyltransferase (COMT), a major enzyme that aids in the excretion of tea polyphenols in humans. Larger studies are needed to confirm results from this cross-sectional study and to better understand the potentially differing effect of black tea and green tea on circulating estrogen levels and ultimately on the risk of breast cancer.
Received October 4, 2004
Revised November 15, 2004
Accepted January 11, 2005
MOLECULAR EPIDEMIOLOGY AND CANCER PREVENTION
Tea and circulating estrogen levels in postmenopausal Chinese women in singapore
2 Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine, Los Angeles, California 90089
3 Department of Urology, University of Southern California Keck School of Medicine, Los Angeles, California 90089
4 Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore 117597
Anna H. Wu, E-mail: annawu{at}usc.edu
Abstract 
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  L. C. Tan, W.-P. Koh, J.-M. Yuan, R. Wang, W.-L. Au, J. H. Tan, E.-K. Tan, and M. C. Yu Differential Effects of Black versus Green Tea on Risk of Parkinson's Disease in the Singapore Chinese Health Study Am. J. Epidemiol., March 1, 2008; 167(5): 553 - 560. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C.-L. Sun, J.-M. Yuan, W. P. Koh, H.-P. Lee, and M. C. Yu Green tea and black tea consumption in relation to colorectal cancer risk: the Singapore Chinese Health Study Carcinogenesis, October 1, 2007; 28(10): 2143 - 2148. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.-L. Sun, J.-M. Yuan, W.-P. Koh, and M. C. Yu Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies Carcinogenesis, July 1, 2006; 27(7): 1310 - 1315. [Abstract] [Full Text] [PDF]
|
|