Research paper
The specific role of isoflavones on estrogen metabolism in premenopausal women
Study answer
What this study found
Overall, isoflavone supplementation favorably altered estrogen-related measures and menstrual characteristics. The clearest effect was an increase in total menstrual cycle length from baseline to the end of study in the isoflavone group compared with placebo, 3.52 1.35 versus -0.06 1.12, P=0.04. Follicular cycle length also increased in the active group but did not reach statistical significance, 1.46 0.63 versus 0.14 0.43, P=0.08. Hormone patterns were also shifted in a potentially favorable direction, with SHBG increased in 41.4% of women, free estradiol decreased in 53.85%, and estrone…
- Study & population
- This was a placebo-controlled randomized human intervention study in premenopausal, omnivorous women without a history of breast carcinoma.
- Intervention
- Premenopausal women in the active arm received an oral soy protein supplement providing 40 mg of genistein per day (20 mg per dose) for 12 weeks, compared with placebo.
- Key limitation
- The active arm was small, and the intervention lasted only 12 weeks, limiting confidence in durability and clinical relevance.
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Open PDFOriginal abstract
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 supplem…