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Prostatic soy isoflavone concentrations exceed serum levels after dietary supplementation
Author(s) -
Gardner Christopher D.,
Oelrich Beibei,
Liu Jenny P.,
Feldman David,
Franke Adrian A.,
Brooks James D.
Publication year - 2009
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/pros.20922
Subject(s) - daidzein , isoflavones , genistein , prostate , prostate cancer , medicine , soy isoflavones , soy protein , endocrinology , glycitein , phytoestrogens , prostatectomy , cancer , pathology , estrogen
Abstract BACKGROUND The effects of soy isoflavones on prostate cancer may be concentration‐dependent. The impact of soy supplementation on isoflavone concentrations in prostate tissues and serum remain unclear. OBJECTIVE To assess and compare concentrations of soy isoflavones in prostate tissue and serum among 19 men with prostate cancer who had elected to undergo radical prostatectomy. METHODS Participants were randomized to receive either daily soy supplements (82 mg/day aglycone equivalents) or placebos for 2 weeks (14 days) prior to surgery. Serum samples were obtained at the time of the surgery. Isoflavone concentrations were measured by HPLC/ESI‐MS–MS. RESULTS The median (25th, 75th percentile) total isoflavone concentration in the isoflavone‐supplemented group was 2.3 µmol/L (1.2, 6.9) in the prostate tissue and 0.7 µmol/L (0.2, 1.2) in the serum. Total isoflavone concentrations in this group were an average of ∼6‐fold higher in prostate tissue compared to serum; the tissue versus serum ratio was significantly lower for genistein than daidzein, 4‐fold versus 10‐fold, P = 0.003. Tissue and serum levels of isoflavones among the placebo group were negligible with a few exceptions. CONCLUSIONS The findings from the present study suggest that prostate tissue may have the ability to concentrate dietary soy isoflavones to potentially anti‐carcinogenic levels. Prostate 69: 719–726, 2009. © 2009 Wiley‐Liss, Inc.