BETWEEN AND WITHIN SUBJECT VARIABILITY OF BIOMARKERS OF ANTIOXIDANT STATUS IN THE BIOCLAIMS COHORT
Brigitte M. Winklhofer‐Roob, Gernot Faustmann, N Walter, Hildegard Hafner-Gießauf, MC Sattler, Sieglinde Zelzer, Andreas Meinitzer, Beate Tiran, J.M. Roob · Aktuelle Ernährungsmedizin · 2017
Introduction: When studying the metabolic phenotype, not only between but also within subject variability of biomarkers may need to be taken into account. However, variability data is limited. Objectives: The aim of this study was to investigate between and within subject variability of biomarkers of antioxidant status. Methods: In a cross-sectional study, the BIOCLAIMS cohort (1310 subjects, 606 M, 704 F, 18 – 85, 51.3 ± 16.1) years, underwent comprehensive dietary, anthropometric, clinical and biochemical characterization. Biomarkers of antioxidant status included plasma ascorbate, α- and γ-tocopherol, α- and β-carotene, lycopene, β-cryptoxanthin, lutein/zeaxanthin concentrations and erythrocyte glutathione peroxidase activity (GSH-Px). Investigations took place across calendar years, allowing to study seasonal effects. Subsets of the study subjects participated also in longitudinal studies: Seasonal Variability Study (52 subjects, M = F, 12 investigations, at monthly intervals); Menstrual Cycle Study (28 F, not using hormonal contraceptives, 4 investigations, at early and late follicular and mid and late luteal phase); and Day-to-Day Variability Study (12 subjects, 5 investigations, Monday through Friday). Results: Plasma concentrations were (mean ± SD; min-max) for ascorbate 68.2 ± 19.0 (8.90 – 170)µmol/L; α-tocopherol 29.5 ± 7.51 (7.87 – 92.5)µmol/L, γ-tocopherol 1.24 ± 0.699 (0.218 – 7.85)µmol/L, β-carotene (0.85 ± 0.72, 0.034 – 10.0)µmol/L, and lycopene 0.59 ± 0.30 (0.001 – 2.38)µmol/L; erythrocyte GSH-Px activity was 6.21 ± 1.56 (2.01 – 12.13) U/g Hb. Changes across the menstrual cycle were significant for plasma ascorbate ( P 0.8 for vitamin E, > 0.9 for other antioxidants). Conclusion: While day-to-day variability in the absence of changes of dietary intakes are low, seasonal variability in plasma concentrations, resulting from variation in dietary intake patterns, and variability across the menstrual cycle need to be taken into account when using biomarkers of antioxidant status for phenotyping. Funded by European Commission FP7, grant n° 244995, and Federal Ministry of Science, Research and Economy, Austria. Disclosure of Interest: None declared.