Plasma and prostate phytoestrogen concentrations in prostate cancer patients after oral phytoestogen supplementation

BACKGROUND Phytoestrogens have been suggested to reduce the risk of prostate cancer (CaP), but no data exists on how oral phytoestrogen supplementation influences phytoestrogen concentrations in prostate tissue. METHODS Forty men with CaP, assigned for radical prostatectomy, received 240 mg of clover phytoestrogens or placebo daily for a 2‐week period before their operation in a prospective and randomized study. Phytoestrogens were measured in plasma and prostate tissue by time‐resolved fluoroimmunoassay (TR‐FIA). RESULTS All patients had low baseline phytoestrogen concentrations and only 35% had a detectable plasma concentration of equol. Oral supplementation with phytoestrogens induced a statistically significant (P