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Soy consumption alters endogenous estrogen metabolism in postmenopausal women.
Cancer Epidemiol Biomarkers Prev. 2000 Aug; 9(8):781-6.CE

Abstract

Isoflavones are soy phytoestrogens that have been suggested to be anticarcinogenic. Our previous study in premenopausal women suggested that the mechanisms by which isoflavones exert cancer-preventive effects may involve modulation of estrogen metabolism away from production of potentially carcinogenic metabolites [16alpha-(OH) estrone, 4-(OH) estrone, and 4-(OH) estradiol] (X. Xu et al., Cancer Epidemiol. Biomark. Prev., 7: 1101-1108, 1998). To further evaluate this hypothesis, a randomized, cross-over soy isoflavone feeding study was performed in 18 healthy postmenopausal women. The study consisted of three diet periods, each separated by a washout of approximately 3 weeks. Each diet period lasted for 93 days, during which subjects consumed their habitual diets supplemented with soy protein isolate providing 0.1 (control), 1, or 2 mg isoflavones/kg body weight/day (7.1 +/- 1.1, 65 +/- 11, or 132 +/- 22 mg/day). A 72-h urine sample was collected 3 days before the study (baseline) and days 91-93 of each diet period. Urine samples were analyzed for 10 phytoestrogens and 15 endogenous estrogens and their metabolites by a capillary gas chromatography-mass spectrometry method. Compared with the soy-free baseline and very low isoflavone control diet, consumption of 65 mg isoflavones increased the urinary 2/16alpha-(OH) estrone ratio, and consumption of 65 or 132 mg isoflavones decreased excretion of 4-(OH) estrone. When compared with baseline values, consumption of all three soy diets increased the ratio of 2/4-(OH) estrogens and decreased the ratio of genotoxic: total estrogens. These data suggest that both isoflavones and other soy constituents may exert cancer-preventive effects in postmenopausal women by altering estrogen metabolism away from genotoxic metabolites toward inactive metabolites.

Authors+Show Affiliations

Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10952094

Citation

Xu, X, et al. "Soy Consumption Alters Endogenous Estrogen Metabolism in Postmenopausal Women." Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, vol. 9, no. 8, 2000, pp. 781-6.
Xu X, Duncan AM, Wangen KE, et al. Soy consumption alters endogenous estrogen metabolism in postmenopausal women. Cancer Epidemiol Biomarkers Prev. 2000;9(8):781-6.
Xu, X., Duncan, A. M., Wangen, K. E., & Kurzer, M. S. (2000). Soy consumption alters endogenous estrogen metabolism in postmenopausal women. Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, 9(8), 781-6.
Xu X, et al. Soy Consumption Alters Endogenous Estrogen Metabolism in Postmenopausal Women. Cancer Epidemiol Biomarkers Prev. 2000;9(8):781-6. PubMed PMID: 10952094.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Soy consumption alters endogenous estrogen metabolism in postmenopausal women. AU - Xu,X, AU - Duncan,A M, AU - Wangen,K E, AU - Kurzer,M S, PY - 2000/8/22/pubmed PY - 2001/2/28/medline PY - 2000/8/22/entrez SP - 781 EP - 6 JF - Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology JO - Cancer Epidemiol. Biomarkers Prev. VL - 9 IS - 8 N2 - Isoflavones are soy phytoestrogens that have been suggested to be anticarcinogenic. Our previous study in premenopausal women suggested that the mechanisms by which isoflavones exert cancer-preventive effects may involve modulation of estrogen metabolism away from production of potentially carcinogenic metabolites [16alpha-(OH) estrone, 4-(OH) estrone, and 4-(OH) estradiol] (X. Xu et al., Cancer Epidemiol. Biomark. Prev., 7: 1101-1108, 1998). To further evaluate this hypothesis, a randomized, cross-over soy isoflavone feeding study was performed in 18 healthy postmenopausal women. The study consisted of three diet periods, each separated by a washout of approximately 3 weeks. Each diet period lasted for 93 days, during which subjects consumed their habitual diets supplemented with soy protein isolate providing 0.1 (control), 1, or 2 mg isoflavones/kg body weight/day (7.1 +/- 1.1, 65 +/- 11, or 132 +/- 22 mg/day). A 72-h urine sample was collected 3 days before the study (baseline) and days 91-93 of each diet period. Urine samples were analyzed for 10 phytoestrogens and 15 endogenous estrogens and their metabolites by a capillary gas chromatography-mass spectrometry method. Compared with the soy-free baseline and very low isoflavone control diet, consumption of 65 mg isoflavones increased the urinary 2/16alpha-(OH) estrone ratio, and consumption of 65 or 132 mg isoflavones decreased excretion of 4-(OH) estrone. When compared with baseline values, consumption of all three soy diets increased the ratio of 2/4-(OH) estrogens and decreased the ratio of genotoxic: total estrogens. These data suggest that both isoflavones and other soy constituents may exert cancer-preventive effects in postmenopausal women by altering estrogen metabolism away from genotoxic metabolites toward inactive metabolites. SN - 1055-9965 UR - https://www.unboundmedicine.com/medline/citation/10952094/Soy_consumption_alters_endogenous_estrogen_metabolism_in_postmenopausal_women_ L2 - http://cebp.aacrjournals.org/cgi/pmidlookup?view=long&pmid=10952094 DB - PRIME DP - Unbound Medicine ER -