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The specific role of isoflavones on estrogen metabolism in premenopausal women
Author(s) -
Kumar Nagi B.,
Cantor Alan,
Allen Kathy,
Riccardi Diane,
Cox Charles E.
Publication year - 2002
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.10320
Subject(s) - medicine , placebo , estrone , endocrinology , menstrual cycle , hormone , genistein , isoflavones , estrogen , phytoestrogens , menopause , physiology , sex hormone binding globulin , follicular phase , alternative medicine , pathology , androgen
BACKGROUND There is increasing evidence that dietary factors may play a role in the production, metabolism, and bioavailability of sex hormones and their impact on target tissues. The specific objective of this study was to evaluate the effectiveness of supplementing a group of premenopausal women who were free of breast carcinoma with a dietary supplement of isoflavones (40 mg per day) in producing a change in steroid hormones and menstrual cycle length. METHODS Sixty‐eight consecutively recruited, premenopausal, omnivorous women of all races and ethnicities between the ages of 25 years and 55 years were admitted to the study and randomized to an experimental group supplemented with soy (40 mg genistein per day) or to a control group that consumed a placebo for a 12‐week period. Changes in their anthropometric, nutritional, and hormonal biomarkers from early follicular phase were analyzed at baseline and postintervention. RESULTS Serum‐free estradiol and estrone levels decreased moderately in the experimental group. Serum hormone‐binding globulin levels increased in 41.4% of women in the experimental group compared with 37.5% of women in the placebo group. Free estradiol decreased in 53.85% of women in the experimental group compared with 37.5% of women in the placebo group. Estrone decreased in 55.56% of women in the experimental group compared with 42.86% in the placebo group. Those women in the experimental group who were consuming soy had their mean menstrual cycle length increased by 3.52 days compared with a mean decrease of 0.06 days for women in the placebo group ( P = 0.04) from baseline to the third menstrual cycle. In addition, women who were taking soy had their mean follicular phase increase by 1.46 days compared with a mean increase of 0.14 days for women who were taking the placebo ( P = 0.08). CONCLUSIONS These data suggest that increased isoflavone intake affects estrogen metabolism by altering the steroid hormone concentrations and menstrual cycle length, thereby demonstrating a potential to reduce the risk for breast carcinoma. Cancer 2002;94:1166–74. © 2002 American Cancer Society. DOI 10.1002/cncr.10320