Original Article The specific role of isoflavones on estrogen metabolism in premenopausal women Nagi B. Kumar, Ph.D., R.D. 1 *, Alan Cantor, Ph.D. 2, Kathy Allen, R.D. 1, Diane Riccardi, R.D., M.P.H. 1, Charles E. Cox, M.D. 3 1Department of Nutrition, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 2Department of Cancer Control, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 3Department of Surgery, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida email: Nagi B. Kumar (kumar@moffitt.usf.edu) Abstract 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 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.