Relationship between dietary non-enzymatic antioxidant capacity and type 2 diabetes risk in the Japan Public Health Center-based Prospective Study

Objective: Intake of antioxidants may reduce the risk for type 2 diabetes (T2D) by reducing oxidative stress. However, it is unclear whether dietary non-enzymatic antioxidant capacity (NEAC), which represents the cumulative action of dietary antioxidants and their synergistic effects in foods, is associated with decreased T2D risk. The aim of this study was to investigate the associations between dietary NEAC and T2D. Methods: The study included 64 660 adults (27 809 men and 36 851 women), 44 to 76 y of age without history of T2D in the Japan Public Health Center-based Prospective Study. Dietary NEAC was estimated using databases of NEAC measurements compiled from results for three different assays: ferric reducing-antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and total radical-trapping antioxidant parameter (TRAP). A multiple logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of self-reported physician-diagnosed T2D over 5 y with adjustment for potential confounders. Results: In all, 1191 cases of newly diagnosed T2D were reported. Dietary NEACs were not significantly associated with T2D. The multivariate-adjusted ORs were 1.04 (95% CI, 0.88–1.23; Ptrend = 0.56) for FRAP, 1.11 (95% CI, 0.93–1.32; Ptrend = 0.26) for ORAC, and 0.99 (95% CI, 0.84–1.18; Ptrend = 0.84) for TRAP. Similar associations were observed in men and women (Pinteraction = 0.46 for FRAP, 0.35 for ORAC, and 0.63 for TRAP). In stratified analyses of major prooxidant factors, no notable associations with smoking and obesity status were observed. Conclusions: This finding suggests that dietary NEAC may not be appreciably associated with T2D in Japanese adults.