Soy isoflavone intake and estrogen excretion patterns in young women: effect of probiotic administration.
BACKGROUND
Soy isoflavones may lower breast cancer risk through altered hepatic estrogen metabolism, leading to increased urinary excretion ratios of 2-hydroxyestrone (20HE1) to 16a-hydroxyestrone (16alphaOHE1).


METHODS
Urinary excretion of 20HE1/16alphaOHE1 was measured in 36 healthy, pre-menstrual women before and after ingestion of a soy-protein formula containing 120 mg of isoflavone daily for one month. Since isoflavone absorption and metabolism depends on intestinal bacteria, effects of co-administration of Lactobacillus GG (2 x 10(12)) on estrogen ratios and isoflavone excretion were studied. Urinary isoflavone excretion measurements assessed compliance.


RESULTS
Soy isoflavone ingestion induced quantitative differences in urinary excretion of estrogen metabolites and isoflavones but failed to alter 20HE1/16alphaOHE1 ratios. Co-administration of Lactobacillus GG with soy reduced excretion of total and individual isoflavones by 40% (p=0.08), without altering 2OHE1/16alphaOHE1 ratios.


CONCLUSIONS
Isoflavone-rich soy protein administration alone, or with probiotic supplement, did not alter urinary excretion of estrogen metabolites in premenopausal women. However, adding concentrated probiotics may alter isoflavone bioavailability.
Cohen
Leonard A
LA
Institute for Cancer Prevention, Valhalla, NY, USA. Lac65@earthlink.net
Crespin
Jeffrey S
JS
Wolper
Carla
C
Zang
Edith A
EA
Pittman
Brian
B
Zhao
Zhonglin
Z
Holt
Peter R
PR
D000328:Adult; D001943:Breast Neoplasms / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D006801:Humans; D006894:Hydroxyestrones / Q000652:urine*; D007529:Isoflavones / Q000008:administration & dosage*; D008137:Longitudinal Studies; D008875:Middle Aged; D009376:Neoplasms, Hormone-Dependent / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D017697:Premenopause; D019936:Probiotics / Q000008:administration & dosage*; D013025:Glycine max
D006894:Hydroxyestrones; D007529:Isoflavones; C026702:16-hydroxyestrone; C024980:2-hydroxyestrone