Dietary antioxidant capacity and risk of type 2 diabetes in the large prospective E3N-EPIC cohort

Aims/hypothesis: Recent evidence suggests that oxidative stress may contribute to the pathogenesis of type 2 diabetes. The diet, and especially fruit and vegetables, contains a variety of compounds with antioxidant activity, which may have cumulative/synergistic antioxidant effects. The total antioxidant capacity, an index derived from dietary intake, is a single estimate of antioxidant capacity from all dietary antioxidants. The main aim of this study was to investigate the relationship between total antioxidant capacity and risk of type 2 diabetes. Methods: Among 64,223 women (mean age 52 ± 7 years) from the French E3N-European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, 1751 women had validated type 2 diabetes during 15 years of follow-up. The total antioxidant capacity was estimated with the ferric ion-reducing antioxidant power (FRAP) method. Adjusted Cox proportional hazards regression models were used to calculate HRs and 95% CIs for the associations between total antioxidant capacity and type 2 diabetes risk, adjusted for potential confounders. Results: In multivariable models, higher levels of total antioxidant capacity were associated with a lower risk of type 2 diabetes. Compared with women in the lowest quintile, women in the third, fourth and fifth quintiles for total antioxidant capacity had HRs of 0.74 (95% CI 0.63, 0.86), 0.70 (95% CI 0.59, 0.83) and 0.73 (95% CI 0.60, 0.89), respectively. The inverse association between total antioxidant capacity and risk of type 2 diabetes was linear up to values of 15 mmol/day, after which the effect reached a plateau. Conclusions/interpretation: Our findings suggest that the total antioxidant capacity may play an important role in reducing the risk of type 2 diabetes in middle-aged women. More studies are warranted to better understand the biological mechanisms underlying this inverse association.