title: Reproducibility of plasma alkylresorcinols during a 6-week rye intervention study in men with prostate cancer.
abstract: Alkylresorcinols (AR), phenolic lipids exclusively present in the outer parts of wheat and rye grains, have been proposed as concentration biomarkers of whole-grain wheat and rye intake. A key feature of a good biomarker is high reproducibility, which indicates how accurately a single sample reflects the true mean biomarker concentration caused by a certain intake. In this study, the short- to medium-term reproducibility of plasma AR was determined using samples from a crossover intervention study, where men with prostate cancer (n = 17) were fed rye whole-grain/bran or refined wheat products for 6-wk periods. AR homologs C17:0 and C21:0 differed between the treatments (P < 0.001). The reproducibility determined by the intraclass correlation coefficient (ICC) was high (intervention period 1: ICC = 0.90 [95% CI = 0.82-0.98], intervention period 2: ICC = 0.88 [95% CI = 0.78-0.98]). The results show that a single fasting plasma sample could be used to estimate the mean plasma AR concentration during a 6-wk intervention period with constant intake at a precision of +/- 20% (80% CI). This suggests that the plasma AR concentration can be used as a reliable short- to medium-term biomarker for whole-grain wheat and rye under intervention conditions where intake is kept constant.
authors.affiliation: Department of Food Science, Swedish University of Agriculture Science, SE-75007 Uppsala, Sweden. rikard.landberg@lmv.slu.se
authors.forename: Rikard
authors.initials: R
authors.lastname: Landberg
authors.forename: Afaf
authors.initials: A
authors.lastname: Kamal-Eldin
authors.forename: Swen-Olof
authors.initials: SO
authors.lastname: Andersson
authors.forename: Jan-Erik
authors.initials: JE
authors.lastname: Johansson
authors.forename: Jie-Xian
authors.initials: JX
authors.lastname: Zhang
authors.forename: Göran
authors.initials: G
authors.lastname: Hallmans
authors.forename: Per
authors.initials: P
authors.lastname: Aman