Alkylresorcinol metabolites in urine and plasma as potential biomarkers of rye and wheat fiber consumption in prostate cancer patients and controls.

Alkylresorcinols (ARs) are phytochemicals mainly associated with rye/wheat bran. Plasma ARs and their plasma and urine metabolites are considered as biomarkers for whole-grain rye/wheat intake. However ARs metabolite day and night variations have not been studied in prostate cancer patients yet. We investigated ARs metabolites 3, 5-dihydroxy-benzoic acid (DHBA), and 3-(3, 5-dihydroxyphenyl)-1-propanoic acid (DHPPA) in urine and plasma in prostate cancer patients and in control group. DHPPA in 12-h overnight urine correlated with the intake of rye bread and bread fiber across short time periods (3 days). Plasma DHPPA concentration was significantly greater in the prostate cancer group than in the control group. DHPPA and DHBA excretion was significantly higher in the overnight urine than in day urine in the prostate cancer group but not in the control group. DHPPA concentration in plasma in the prostate cancer group did not depend on the intake of rye bread in the previous day, suggesting an impaired metabolism of ARs metabolites in the prostate cancer group. The results of this study suggest DHPPA in 12-h overnight urine as a biomarker to estimate the intake of rye bread and bread fiber.