Physical activity, body size, and estrogen metabolism in women.
OBJECTIVE
Physical activity has demonstrable effects on estrogen levels in pre- and postmenopausal women. Increased oxidation of estrone to 2-hydroxyestrone (2HE) relative to 16alpha-hydroxyestrone (16HE) has been hypothesized to reduce breast cancer risk, but little is known about the effect of physical activity and body size in relation to the ratio of 2HE and 16HE in women. We examined these relationships in cross-sectional analyses of 157 North American and Chinese women.


METHODS
Physical activity was assessed using validated questionnaires. Adiposity was assessed as body mass index (BMI, kg/m2) and by anthropometric methods (% body fat). Estrone metabolites, 2HE and 16HE, were determined from urine via ELISA.


RESULTS
Regression analyses on the 2HE/16HE ratio revealed an interaction between leisure-time physical activities and adiposity in both North American and Chinese women (p < or = 0.05). Women reporting low levels of leisure-time physical activity who had higher BMI levels had 2HE/16HE ratios that were lower than their lean counterparts. In contrast, women with higher BMI levels that were physically active maintained higher 2HE/16HE ratios.


CONCLUSIONS
These findings suggest that physical activity participation has the potential to modify the adverse effect of increased adiposity on estrogen metabolism in North American and Chinese women.
Vanderbilt-Ingram Cancer Center, Center for Health Services Research, Vanderbilt University Medical Center, Medical Center East, Suite 6100, Nashville, TN 37232-8300, USA. charles.matthews@vanderbilt.edu
Charles E
CE
Matthews
Jay H
JH
Fowke
Qi
Q
Dai
H
H
Leon Bradlow
Fan
F
Jin
Xiao-Ou
XO
Shu
Yu-Tang
YT
Gao
Christopher
C
Longcope
James R
JR
Hebert
Wei
W
Zheng
D000273:Adipose Tissue; D000368:Aged; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000208:ethnology / Q000209:etiology* / Q000517:prevention & control*; D002681:China / Q000208:ethnology; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D004967:Estrogens / Q000378:metabolism*; D015444:Exercise; D005260:Female; D006801:Humans; D008875:Middle Aged; D009656:North America / Q000208:ethnology; D011998:Recreation; D012044:Regression Analysis
D004967:Estrogens