This Article Full Text Full Text (PDF) A correction has been published Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Duncan, A. M. Articles by Kurzer, M. S. Search for Related Content PubMed PubMed Citation Articles by Duncan, A. M. Articles by Kurzer, M. S.

Modest Hormonal Effects of Soy Isoflavones in Postmenopausal Women¹

Department of Food Science and Nutrition (A.M.D., K.E.W.U., X.X., M.S.K.), University of Minnesota, St. Paul, MN, 55108 ; the Department of Obstetrics and Gynecology (J.L.), University of Minnesota, Minneapolis, Minnesota, 55455 ; Department of Obstetrics and Gynecology (W.R.P.), University of Rochester, Rochester, New York, 14642

Address correspondence and requests for reprints to: Mindy S. Kurzer, Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, Minnesota 55108; E-mail: mkurzer{at}tc.umn.edu

Soy isoflavones have been hypothesized to exert hormonal effects in postmenopausal women. To test this hypothesis, we studied the effects of three soy powders containing different levels of isoflavones in 18 postmenopausal women. Isoflavones were consumed relative to body weight [control: 0.11 ± 0.01; low isoflavone (low-iso): 1.00 ± 0.01; high isoflavone (high-iso): 2.00 ± 0.02 mg/kg/day] for 93 days each in a randomized crossover design. Blood was collected on day 1 of the study (baseline) and days 36–38, 64–66, and 92–94 of each diet period, for analysis of estrogens, androgens, gonadotropins, sex hormone binding globulin (SHBG), prolactin, insulin, cortisol, and thyroid hormones. Vaginal cytology specimens were obtained at baseline and at the end of each diet period, and endometrial biopsies were performed at baseline and at the end of the high-iso diet period, to provide additional measures of estrogen action. Overall, compared with the control diet, the effects of the low-iso and high-iso diets were modest in degree. The high-iso diet resulted in a small but significant decrease in estrone-sulfate (E₁-S), a trend toward lower estradiol (E₂) and estrone (E₁), and a small but significant increase in SHBG. For the other hormones, the few significant changes noted were also small and probably not of physiological importance. There were no significant effects of the low-iso or high-iso diets on vaginal cytology or endometrial biopsy results. These data suggest that effects of isoflavones on plasma hormones per se are not significant mechanisms by which soy consumption may exert estrogen-like effects in postmenopausal women. These data also show that neither isoflavones nor soy exert clinically important estrogenic effects on vaginal epithelium or endometrium.

This article has been cited by other articles:

				L. Hooper, J.J. Ryder, M.S. Kurzer, J.W. Lampe, M.J. Messina, W.R. Phipps, and A. Cassidy Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis Hum. Reprod. Update, July 1, 2009; 15(4): 423 - 440. [Abstract] [Full Text] [PDF]

				M. Atteritano, H. Marini, L. Minutoli, F. Polito, A. Bitto, D. Altavilla, S. Mazzaferro, R. D'Anna, M. L. Cannata, A. Gaudio, et al. Effects of the Phytoestrogen Genistein on Some Predictors of Cardiovascular Risk in Osteopenic, Postmenopausal Women: A Two-Year Randomized, Double-Blind, Placebo-Controlled Study J. Clin. Endocrinol. Metab., August 1, 2007; 92(8): 3068 - 3075. [Abstract] [Full Text] [PDF]

				A. H. Wu, M. C. Yu, C.-C. Tseng, F. Z. Stanczyk, and M. C. Pike Diabetes and risk of breast cancer in Asian-American women Carcinogenesis, July 1, 2007; 28(7): 1561 - 1566. [Abstract] [Full Text] [PDF]

				Y.-L. Low, A. M. Dunning, M. Dowsett, E. Folkerd, D. Doody, J. Taylor, A. Bhaniani, R. Luben, K.-T. Khaw, N. J. Wareham, et al. Phytoestrogen Exposure Is Associated with Circulating Sex Hormone Levels in Postmenopausal Women and Interact with ESR1 and NR1I2 Gene Variants Cancer Epidemiol. Biomarkers Prev., May 1, 2007; 16(5): 1009 - 1016. [Abstract] [Full Text] [PDF]

				C. E. Wood, T. C. Register, and J.M. Cline Soy isoflavonoid effects on endogenous estrogen metabolism in postmenopausal female monkeys Carcinogenesis, April 1, 2007; 28(4): 801 - 808. [Abstract] [Full Text] [PDF]

				C. Atkinson, J. W Lampe, D. Scholes, C. Chen, K. Wahala, and S. M Schwartz Lignan and isoflavone excretion in relation to uterine fibroids: a case-control study of young to middle-aged women in the United States. Am. J. Clinical Nutrition, September 1, 2006; 84(3): 587 - 593. [Abstract] [Full Text] [PDF]

				C. E. Wood, S. E. Appt, T. B. Clarkson, A. A. Franke, C. J. Lees, D. R. Doerge, and J. M. Cline Effects of High-Dose Soy Isoflavones and Equol on Reproductive Tissues in Female Cynomolgus Monkeys Biol Reprod, September 1, 2006; 75(3): 477 - 486. [Abstract] [Full Text] [PDF]

				A. H Wu, F. Z Stanczyk, C. Martinez, C.-C. Tseng, S. Hendrich, P. Murphy, S. Chaikittisilpa, D. O Stram, and M. C Pike A controlled 2-mo dietary fat reduction and soy food supplementation study in postmenopausal women Am. J. Clinical Nutrition, May 1, 2005; 81(5): 1133 - 1141. [Abstract] [Full Text] [PDF]

				B. L. Dillingham, B. L. McVeigh, J. W. Lampe, and A. M. Duncan Soy Protein Isolates of Varying Isoflavone Content Exert Minor Effects on Serum Reproductive Hormones in Healthy Young Men J. Nutr., March 1, 2005; 135(3): 584 - 591. [Abstract] [Full Text] [PDF]

				Y. T. van der Schouw, L. Sampson, W. C. Willett, and E. B. Rimm The Usual Intake of Lignans but Not That of Isoflavones May Be Related to Cardiovascular Risk Factors in U.S. Men J. Nutr., February 1, 2005; 135(2): 260 - 266. [Abstract] [Full Text] [PDF]

				Y.-L. Low, J. I. Taylor, P. B. Grace, M. Dowsett, S. Scollen, A. M. Dunning, A. A. Mulligan, A. A. Welch, R. N. Luben, K.-T. Khaw, et al. Phytoestrogen Exposure Correlation with Plasma Estradiol in Postmenopausal Women in European Prospective Investigation of Cancer and Nutrition-Norfolk May Involve Diet-Gene Interactions Cancer Epidemiol. Biomarkers Prev., January 1, 2005; 14(1): 213 - 220. [Abstract] [Full Text] [PDF]

				L. I Mennen, R. Walker, C. Bennetau-Pelissero, and A. Scalbert Risks and safety of polyphenol consumption Am. J. Clinical Nutrition, January 1, 2005; 81(1): 326S - 329S. [Abstract] [Full Text] [PDF]

				C. E. Wood, T. C. Register, M. S. Anthony, N. D. Kock, and J. M. Cline Breast and Uterine Effects of Soy Isoflavones and Conjugated Equine Estrogens in Postmenopausal Female Monkeys J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3462 - 3468. [Abstract] [Full Text] [PDF]

				E. Nikander, A. Tiitinen, K. Laitinen, M. Tikkanen, and O. Ylikorkala Effects of Isolated Isoflavonoids on Lipids, Lipoproteins, Insulin Sensitivity, and Ghrelin in Postmenopausal Women J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3567 - 3572. [Abstract] [Full Text] [PDF]

				C. E. Wood, J. M. Cline, M. S. Anthony, T. C. Register, and J. R. Kaplan Adrenocortical Effects of Oral Estrogens and Soy Isoflavones in Female Monkeys J. Clin. Endocrinol. Metab., May 1, 2004; 89(5): 2319 - 2325. [Abstract] [Full Text] [PDF]

				C. W. Xiao, M. R. L'Abbe, G. S. Gilani, G. M. Cooke, I. H. Curran, and S. A. Papademetriou Dietary Soy Protein Isolate and Isoflavones Modulate Hepatic Thyroid Hormone Receptors in Rats J. Nutr., April 1, 2004; 134(4): 743 - 749. [Abstract] [Full Text] [PDF]

				H. J Teede, F. S Dalais, and B. P McGrath Dietary soy containing phytoestrogens does not have detectable estrogenic effects on hepatic protein synthesis in postmenopausal women Am. J. Clinical Nutrition, March 1, 2004; 79(3): 396 - 401. [Abstract] [Full Text] [PDF]

				J. D Brooks, W. E Ward, J. E Lewis, J. Hilditch, L. Nickell, E. Wong, and L. U Thompson Supplementation with flaxseed alters estrogen metabolism in postmenopausal women to a greater extent than does supplementation with an equal amount of soy Am. J. Clinical Nutrition, February 1, 2004; 79(2): 318 - 325. [Abstract] [Full Text] [PDF]

				J. M. Cline, A. A. Franke, T. C. Register, D. L. Golden, and M. R. Adams Effects of Dietary Isoflavone Aglycones on the Reproductive Tract of Male and Female Mice Toxicol Pathol, January 1, 2004; 32(1): 91 - 99. [Abstract] [PDF]

				S C Conrad, H Chiu, and B L Silverman Soy formula complicates management of congenital hypothyroidism Arch. Dis. Child., January 1, 2004; 89(1): 37 - 40. [Abstract] [Full Text] [PDF]

				S. Yamamoto, T. Sobue, M. Kobayashi, S. Sasaki, and S. Tsugane Soy, Isoflavones, and Breast Cancer Risk in Japan J Natl Cancer Inst, June 18, 2003; 95(12): 906 - 913. [Abstract] [Full Text] [PDF]

				W. A. Weiger, M. Smith, H. Boon, M. A. Richardson, T. J. Kaptchuk, and D. M. Eisenberg Advising Patients Who Seek Complementary and Alternative Medical Therapies for Cancer Ann Intern Med, December 3, 2002; 137(11): 889 - 903. [Abstract] [Full Text] [PDF]

				U. A. Kayisli, C. A. H. Aksu, M. Berkkanoglu, and A. Arici Estrogenicity of Isoflavones on Human Endometrial Stromal and Glandular Cells J. Clin. Endocrinol. Metab., December 1, 2002; 87(12): 5539 - 5544. [Abstract] [Full Text] [PDF]

				L. T Bloedon, A R. Jeffcoat, W. Lopaczynski, M. J Schell, T. M Black, K. J Dix, B. F Thomas, C. Albright, M. G Busby, J. A Crowell, et al. Safety and pharmacokinetics of purified soy isoflavones: single-dose administration to postmenopausal women Am. J. Clinical Nutrition, November 1, 2002; 76(5): 1126 - 1137. [Abstract] [Full Text] [PDF]

				V. Jayagopal, P. Albertazzi, E. S. Kilpatrick, E. M. Howarth, P. E. Jennings, D. A. Hepburn, and S. L. Atkin Beneficial Effects of Soy Phytoestrogen Intake in Postmenopausal Women With Type 2 Diabetes Diabetes Care, October 1, 2002; 25(10): 1709 - 1714. [Abstract] [Full Text] [PDF]

				Q. Dai, A. A. Franke, F. Jin, X.-O. Shu, J. R. Hebert, L. J. Custer, J. Cheng, Y.-T. Gao, and W. Zheng Urinary Excretion of Phytoestrogens and Risk of Breast Cancer among Chinese Women in Shanghai Cancer Epidemiol. Biomarkers Prev., September 1, 2002; 11(9): 815 - 821. [Abstract] [Full Text] [PDF]

				A. H. Wu, F. Z. Stanczyk, A. Seow, H.-P. Lee, and M. C. Yu Soy Intake and Other Lifestyle Determinants of Serum Estrogen Levels among Postmenopausal Chinese Women in Singapore Cancer Epidemiol. Biomarkers Prev., September 1, 2002; 11(9): 844 - 851. [Abstract] [Full Text] [PDF]

				D. J. Jenkins, C. W. Kendall, C.-J. C Jackson, P. W Connelly, T. Parker, D. Faulkner, E. Vidgen, S. C Cunnane, L. A Leiter, and R. G Josse Effects of high- and low-isoflavone soyfoods on blood lipids, oxidized LDL, homocysteine, and blood pressure in hyperlipidemic men and women Am. J. Clinical Nutrition, August 1, 2002; 76(2): 365 - 372. [Abstract] [Full Text] [PDF]

				J. L. Balk, D. A. Whiteside, G. Naus, E. DeFerrari, and J. M. Roberts A Pilot Study of the Effects of Phytoestrogen Supplementation on Postmenopausal Endometrium Reproductive Sciences, July 1, 2002; 9(4): 238 - 242. [Abstract] [PDF]

				J L Burton and M Wells The effect of phytoestrogens on the female genital tract J. Clin. Pathol., June 1, 2002; 55(6): 401 - 407. [Abstract] [Full Text] [PDF]

				E. A. Lucas, R. D. Wild, L. J. Hammond, D. A. Khalil, S. Juma, B. P. Daggy, B. J. Stoecker, and B. H. Arjmandi Flaxseed Improves Lipid Profile without Altering Biomarkers of Bone Metabolism in Postmenopausal Women J. Clin. Endocrinol. Metab., April 1, 2002; 87(4): 1527 - 1532. [Abstract] [Full Text] [PDF]

				J. Nicholls, B. L. Lasley, S. T. Nakajima, K. D. R. Setchell, and B. O. Schneeman Effects of Soy Consumption on Gonadotropin Secretion and Acute Pituitary Responses to Gonadotropin-Releasing Hormone in Women J. Nutr., April 1, 2002; 132(4): 708 - 714. [Abstract] [Full Text] [PDF]

				K. I. Block, A. Constantinou, L. Hilakivi-Clarke, C. Hughes, D. Tripathy, J. A. Tice, K. Block, and K. Block Point-Counterpoint: Soy Intake for Breast Cancer Patients Integr Cancer Ther, March 1, 2002; 1(1): 90 - 100. [PDF]

				S. A. Whitehead, J. E. Cross, C. Burden, and M. Lacey Acute and chronic effects of genistein, tyrphostin and lavendustin A on steroid synthesis in luteinized human granulosa cells Hum. Reprod., March 1, 2002; 17(3): 589 - 594. [Abstract] [Full Text] [PDF]

				G. E. Hale, C. L. Hughes, and J. M. Cline Endometrial Cancer: Hormonal Factors, the Perimenopausal ""Window of Risk,"" and Isoflavones J. Clin. Endocrinol. Metab., January 1, 2002; 87(1): 3 - 15. [Abstract] [Full Text] [PDF]

				V. W Persky, M. E Turyk, L. Wang, S. Freels, R. Chatterton Jr, S. Barnes, J. Erdman Jr, D. W Sepkovic, H L. Bradlow, and S. Potter Effect of soy protein on endogenous hormones in postmenopausal women Am. J. Clinical Nutrition, January 1, 2002; 75(1): 145 - 153. [Abstract] [Full Text] [PDF]

				J. E. Burdette, J. Liu, D. Lantvit, E. Lim, N. Booth, K. P. L. Bhat, S. Hedayat, R. B. Van Breemen, A. I. Constantinou, J. M. Pezzuto, et al. Trifolium pratense (Red Clover) Exhibits Estrogenic Effects In Vivo in Ovariectomized Sprague-Dawley Rats J. Nutr., January 1, 2002; 132(1): 27 - 30. [Abstract] [Full Text] [PDF]

				M. J. Messina and C. L. Loprinzi Soy for Breast Cancer Survivors: A Critical Review of the Literature J. Nutr., November 1, 2001; 131(11): 3095S - 3108. [Abstract] [Full Text] [PDF]

				D. Goodman-Gruen and D. Kritz-Silverstein Usual Dietary Isoflavone Intake Is Associated with Cardiovascular Disease Risk Factors in Postmenopausal Women J. Nutr., April 1, 2001; 131(4): 1202 - 1206. [Abstract] [Full Text]

				K. E Wangen, A. M Duncan, X. Xu, and M. S Kurzer Soy isoflavones improve plasma lipids in normocholesterolemic and mildly hypercholesterolemic postmenopausal women Am. J. Clinical Nutrition, February 1, 2001; 73(2): 225 - 231. [Abstract] [Full Text] [PDF]

				F. Berrino, C. Bellati, G. Secreto, E. Camerini, V. Pala, S. Panico, G. Allegro, and R. Kaaks Reducing Bioavailable Sex Hormones through a Comprehensive Change in Diet: the Diet and Androgens (DIANA) Randomized Trial Cancer Epidemiol. Biomarkers Prev., January 1, 2001; 10(1): 25 - 33. [Abstract] [Full Text]

				K. E. Wangen, A. M. Duncan, B. E. Merz-Demlow, X. Xu, R. Marcus, W. R. Phipps, and M. S. Kurzer Effects of Soy Isoflavones on Markers of Bone Turnover in Premenopausal and Postmenopausal Women J. Clin. Endocrinol. Metab., September 1, 2000; 85(9): 3043 - 3048. [Abstract] [Full Text]

				X. Xu, A. M. Duncan, K. E. Wangen, and M. S. Kurzer Soy Consumption Alters Endogenous Estrogen Metabolism in Postmenopausal Women Cancer Epidemiol. Biomarkers Prev., August 1, 2000; 9(8): 781 - 786. [Abstract] [Full Text]

				A. M. Pino, L. E. Valladares, M. A. Palma, A. M. Mancilla, M. Yáñez, and C. Albala Dietary Isoflavones Affect Sex Hormone-Binding Globulin Levels in Postmenopausal Women J. Clin. Endocrinol. Metab., August 1, 2000; 85(8): 2797 - 2800. [Abstract] [Full Text]

				M. S. Kurzer Hormonal Effects of Soy Isoflavones: Studies in Premenopausal and Postmenopausal Women J. Nutr., March 1, 2000; 130(3): 660 - 660. [Full Text]

				J. An, C. Tzagarakis-Foster, T. C. Scharschmidt, N. Lomri, and D. C. Leitman Estrogen Receptor beta -Selective Transcriptional Activity and Recruitment of Coregulators by Phytoestrogens J. Biol. Chem., May 18, 2001; 276(21): 17808 - 17814. [Abstract] [Full Text] [PDF]