Original Article

Prostatic soy isoflavone concentrations exceed serum levels after dietary supplementation

  1. Christopher D. Gardner1,*,
  2. Beibei Oelrich1,
  3. Jenny P. Liu1,
  4. David Feldman2,
  5. Adrian A. Franke3,
  6. James D. Brooks4

Article first published online: 29 JAN 2009

DOI: 10.1002/pros.20922

Issue

The Prostate

The Prostate

Volume 69, Issue 7, pages 719–726, 15 May 2009

Additional Information

How to Cite

Gardner, C. D., Oelrich, B., Liu, J. P., Feldman, D., Franke, A. A. and Brooks, J. D. (2009), Prostatic soy isoflavone concentrations exceed serum levels after dietary supplementation. The Prostate, 69: 719–726. doi: 10.1002/pros.20922

Author Information

  1. 1

    Department of Medicine, Stanford Prevention Research Center, Stanford University Medical School, Stanford, California

  2. 2

    Endocrinology, Gerontology and Metabolism Division, Department of Medicine, Stanford University Medical School, Stanford, California

  3. 3

    Cancer Research Center of Hawai'I, Honolulu, Hawai'I

  4. 4

    Department of Urology, Stanford University Medical School, Stanford, California

*Medical School Office Building, Room X310, 251 Campus Drive, Stanford, CA 94305-5411.

Publication History

  1. Issue published online: 13 APR 2009
  2. Article first published online: 29 JAN 2009
  3. Manuscript Accepted: 11 DEC 2008
  4. Manuscript Received: 2 SEP 2008

Funded by

  • NIH/NCCAM. Grant Number: AT00486
  • NIH/NCI. Grant Number: P30 CA71789
  • NIH/NCCR Speical Instrumentation Grant. Grant Number: S10-RR020890

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Keywords:

  • soy isoflavone;
  • prostate cancer;
  • genistein;
  • daidzein

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.

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