Lack of significant genotoxicity of purified soy isoflavones (genistein, daidzein, and glycitein) in 20 patients with prostate cancer.

Background: Genistein may be useful in the prevention or treatment of prostate cancer; however, it causes genetic damage in cultured human cells.

Objective: The objective was to assess the potential genotoxicity of a purified soy unconjugated isoflavone mixture in men with prostate cancer.

Design: Twenty patients with prostate cancer were treated with 300 mg genistein/d for 28 d and then with 600 mg/d for another 56 d.