Some clinical trials have shown that high phytoestrogen intake
may decrease serum concentrations of prostate-specific antigen
(PSA), and phytoestrogens may also lower prostate cancer
risk. It was the aim of this study to examine the relationship between
the serum PSA level and urine phytoestrogen concentration
in generally healthy U.S. men. Eight hundred twenty-four
men, 40+ yr old without prostate cancer, who participated in the
2001–2004 NHANES surveys, were included in the analysis. The
association of total PSA, free PSA, and PSA ratio [free PSA/total
PSA ∗ 100] with concentrations of isoflavones and lignans (standardized
for urinary creatinine concentration) was examined using
multivariable-adjusted linear and logistic regression models.
The linear regression analyses showed no clear association between
creatinine-standardized urinary phytoestrogen concentrations
and serum total or free PSA levels or PSA ratio. However, the
odds of having a PSA ratio