Intake of fruit, vegetables, and antioxidants and risk of type 2 diabetes: systematic review and meta-analysis

Background The public health recommendation is to consume five or more servings of fruit and vegetables daily, but the association between the intake of fruit and vegetables and the risk of type 2 diabetes is unclear. Methods To examine the association between the intake of fruit, vegetables, and antioxidants and the risk of type 2 diabetes, prospective cohort studies were sought, with measures of intakes at baseline and incident diabetes at follow-up. Results Five cohort studies of fruit and vegetables intake and the risk of diabetes were included, incorporating 167 128 participants and 4858 incident cases of type 2 diabetes, with a mean follow-up of 13 years. The relative risk of type 2 diabetes for consuming five or more servings of fruit and vegetables daily was 0.96 (95% Cl, 0.79-1.17, P = 0.96), 1.01 (0.88-1.15, P = 0.88) for three or more servings of fruit, and 0.97 (0.86-1.10, p = 0.59) for three or more servings of vegetables. Nine cohort studies of antioxidant intake and the risk of diabetes were also identified, incorporating 139 793 participants and 8813 incident cases of type 2 diabetes, with a mean follow-up of 13 years. The pooled relative risk was 0.87 (0.79-0.98, P = 0.02) for the highest compared with the lowest antioxidant intake. Conclusions The consumption of three or more daily servings of fruit or vegetables was not associated with a substantial reduction in the risk of type 2 diabetes. The intake of antioxidants was associated with a 13% reduction in risk, mainly attributed to vitamin E. These results are not supported by randomized, controlled trials of vitamin supplements, therefore the findings might not be causal, and the discrepancy remains unclear.