28 juni 2012: onderaan hebben we het abstract van onderstaande studie toegevoegd. Het volledige studierapport The Specific Role of Isoflavones on Estrogen Metabolism in Premenopausal Women kunt u gratis inzien op de website van het NIH

Mei 2002: Bron Reuters en Cancer

Hoewel deze studie niet is gedaan bij borstkankerpatiënten lijken de uitkomsten van deze studie belangrijk voor borstkanker en eierstokkanker. Isoflavonen (soja, genisteïne enz.) hebben significante invloed op de menstruatiewaarden en menstruatieduur. De onderzoekers concluderen dan ook dat dit resultaat belangrijk kan zijn voor borstkankerpatiënten. Dokter Valstar bevestigde dat genisteïne bij patiënten met borstkanker en eierstokkanker een positief effect heeft. Lees het verhaal van een vrouw met eierstokkanker Marjan op pagina uw verhaal die na een half jaar gebruik, van het Houtsmullerdieet/Gerson en suppletie waaronder genisteïne haar tumoren voor meer dan de helft zag slinken en inmiddelsal al vele jaren volledig kankervrij is. En dat zonder welke andere reguliere behandeling dan ook. Onderstaande studieresultaten werden gepubliceerd in het toonaangevende tijdschrift Cancer.

Estrogen Metabolism Affected by Supplemental Isoflavones

NEW YORK (Reuters Health) Mar 11 - Results of a recent study suggest that supplemental soy isoflavones alter the steroid hormone concentrations and menstrual cycle length in premenopausal women. The risk for breast cancer may therefore be reduced by these supplements, according to researchers.
Dr. Nagi B. Kumar and colleagues from the University of South Florida, Tampa, examined whether supplemental isoflavones produce a change in steroid hormones and menstrual cycle length in premenopausal women without breast cancer. Sixty-eight women between the ages of 25 and 55 years were randomized to receive either the soy supplement of genistein at 40 mg per day or placebo over 12 weeks.

The researchers assessed changes in the patients' anthropometric, nutritional, and hormonal biomarkers from early follicular phase at baseline and 12 weeks.

There was a moderate decrease in serum-free estradiol and estrone levels in the experimental group, according to the report in the February 15th issue of Cancer. There were increases of serum hormone-binding globulin levels in 41.4% and 37.5% of the experimental and placebo groups, respectively.

The team notes that 53.85% and 37.5% of the experimental and placebo groups, respectively, had decreases of free estradiol. Decreases in estrone were observed in 55.56% and 42.86% of the subjects, respectively.

"Those participants in the experimental group who consumed soy had their mean menstrual cycle length increased by 3.52 days compared with a mean decrease of 0.06 days in the placebo group (p = 0.04) from baseline to the third menstrual cycle," Dr. Kumar and colleagues explain.

The mean follicular phase increased by 1.46 days in the experimental group, compared with 0.14 days for the placebo group (p = 0.08), they add.

"An increase in menstrual cycle length would reduce the number of menstrual cycles during a lifetime, thereby reducing the total number of times the breast is exposed to estrogen," Dr. Kumar's group points out. Furthermore, "women will spend more days in the increased follicular cycle, when proliferation is at its lowest."

"These effects are mediated by the pituitary gland," they continued, "and long-term effects on the pituitary gland may result in an overall antiestrogenic effect and, thus, in a lower risk for breast carcinoma."

Cancer 2002;94:1166-1174.

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. Author manuscript; available in PMC 2008 May 13.

Published in final edited form as:

Cancer. 2002 February 15; 94(4): 1166–1174.

doi: 10.1002/cncr.10320

PMCID: PMC2377415

NIHMSID: NIHMS47133

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 and Charles E. Cox, M.D.³

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.

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borstkanker, isoflavonen