Skip Navigation


Carcinogenesis Advance Access originally published online on October 9, 2006
Carcinogenesis 2007 28(4):801-808; doi:10.1093/carcin/bgl163
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
28/4/801    most recent
bgl163v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (8)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Wood, C. E.
Right arrow Articles by Cline, J.M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wood, C. E.
Right arrow Articles by Cline, J.M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2006. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Soy isoflavonoid effects on endogenous estrogen metabolism in postmenopausal female monkeys

Charles E. Wood*, Thomas C. Register and J.Mark Cline

Department of Pathology, Section on Comparative Medicine, Wake Forest University School of Medicine Medical Center Boulevard, Winston-Salem, North Carolina 27157-1040, USA

*To whom requests for reprints and correspondence should be addressed. Tel: +1 336 716 1636; Fax: +1 336 716 1515; E-mail: chwood{at}wfubmc.edu

Endogenous estrogens are important determinants of breast cancer risk in postmenopausal women. In this study we evaluated the effects of dietary soy isoflavonoids on endogenous estrogen metabolism in a postmenopausal primate model. Ovariectomized female cynomolgus monkeys were randomized to receive one of three diets for 36 months: (i) isoflavonoid-depleted soy protein isolate (SPI–) (n = 29); (ii) soy protein isolate with 129 mg isoflavonoids/1800 kcal diet (8.6 mg isoflavonoids/kg body weight (BW), expressed in aglycone units) (SPI+) (n = 29) or (iii) isoflavonoid-depleted soy protein isolate with conjugated equine estrogens (CEE) at a dose of 0.625 mg/1800 kcal diet (0.042 mg CEE/kg BW) (n = 30). Mean plasma isoflavonoid concentrations in the SPI+ group were 946.9 ± 135.9 nmol/l, and equol was the primary circulating isoflavonoid (549.7 ± 61.6 nmol/l). The SPI+ diet resulted in lower serum estrone (E1) after 29 (–26%, P = 0.03) and 34 months (–21%, P = 0.04) compared to the SPI– diet, while urinary 2-hydroxyestrone (P = 0.005) and the 2 to 16{alpha}-hydroxyestrone ratio (P < 0.0001) were markedly higher in the SPI+ group compared to SPI–. Isoflavonoid treatment did not significantly alter gene markers of estrogen metabolism or estrogen receptor agonist activity in breast tissue. Within the SPI+ group, higher concentrations of serum equol (but not daidzein or genistein) corresponded to significantly lower serum E1, mammary gland epithelial area and uterine weight (P < 0.01 for all). These findings suggest that long-term exposure to soy isoflavonoids, equol in particular, may facilitate endogenous estrogen clearance and catabolism to more benign 2-hydroxylated metabolites.

Abbreviations: BW, body weight; CEE, conjugated equine estrogens; E1, estrone; E2, estradiol; E1G, estrone glucuronide; E1S, estrone sulfate; 2OH-E1, 2-hydroxyestrone; 16{alpha}OH-E1, 16{alpha}-hydroxyestrone; OC, oral contraceptives

Received May 24, 2006; revised July 13, 2006; accepted August 16, 2006.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Toxicol PatholHome page
J. M. Cline and C. E. Wood
The Mammary Glands of Macaques
Toxicol Pathol, December 1, 2008; 36(7_suppl): 130S - 141S.
[Abstract] [Full Text] [PDF]

Home page
 Cancer Epidemiol. Biomarkers Prev.Home page
L. M. Scott, X. Xu, T. D. Veenstra, J. A. Tooze, C. E. Wood, T. C. Register, N. D. Kock, and J. M. Cline
Past Oral Contraceptive Use and Current Dietary Soy Isoflavones Influence Estrogen Metabolism in Postmenopausal Monkeys (Macaca fascicularis)
Cancer Epidemiol. Biomarkers Prev., October 1, 2008; 17(10): 2594 - 2602.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.