The aim was further to apply the method to evaluate the effect of a diet high in whole grain/bran rye-based foods rich in BXs vs fiber supplemented refined wheat on the structural and quantitative variety of BXs and BX-derived metabolites in plasma samples after regular consumption, and to investigate whether the concentrations of any of such metabolites correlated with PSA levels in men with indolent prostate cancer. The gene discussed is KLK3; the disease is prostate cancer.