Korean J Urol.
2003 Nov;44(11):1093-1097.
Effects of Soybean Metabolites on Prostate Cancer
- Affiliations
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- 1Department of Urology, Chungbuk National University College of Medicine, Cheungju, Korea. wjkim@chungbuk.ac.kr
- 2Department of Urology, Wonju Yonsei University College of Medicine, Wonju, Korea.
- 3Department of Urology, Dong-A University College of Medicine, Busan, Korea.
- 4Department of Urology, Seoul National University College of Medicine, Seoul, Korea.
- 5Department of Urology, Wonkwang University College of Medicine, Iksan, Korea.
- 6Department of Urology, Yonsei University College of Medicine, Seoul, Korea.
Abstract
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PURPOSE: It has been postulated that soybean isoflavones act as inhibitory factors in several cancers. Recently, various in vitro and in vivo experimental studies have demonstrated that these isoflavones inhibit prostate cancer. Therefore, we investigated whether soybean isoflavones influenced the development of prostate cancer by comparing the levels of circulating isoflavones between prostate cancer patients and controls.
MATERIALS AND METHODS
The serum levels of genistein, daidzein and equol were determined using reverse-phase, high-performance liquid chromatography-multiple reaction ion monitoring mass spectrometry(HPLC-MS) and compared in 122 experimental subjects(61 prostate cancer patients and 61 cancer-free controls) from 6 hospitals.
RESULTS
The serum concentrations of genistein, daidzein and equol in the patients were 130.7+/-181.4ng/ml, 53.6+/-69.3ng/ml and 11.37+/-43.4ng/ml, with control values of 95.6+/-95.2ng/ml, 55.2+/-121.8ng/ml and 23.2+/-34.5ng/ml, respectively. There was no statistical difference between the 2 groups. Daidzein non-metabolizers who were unable to degrade daidzein into equol were compared between the patients and the controls, and were found to be significantly more common in the patient group (p=0.001, OR=3.44, 95% CI=1.6243-7.2855). However, the equol/daidzein ratio was significantly lower in the patients than in the controls(p=0.0072). No association between age, stage, Gleason score or isoflavone concentrations was found.
CONCLUSIONS
These results suggest that the capability to produce equol (i.e., the mechanism for the metabolism of daidzein into equol) is closely involved in the lower incidence of prostate cancer, and that a diet based on soybean isoflavones would be useful in preventing prostate cancer.
