Objective: To clarify and quantify the potential dose-response association between the intake of fruit and vegetables and risk of type 2 diabetes.
Design: Meta-analysis and systematic review of prospective cohort studies.
Data source: Studies published before February 2014 identified through electronic searches using PubMed and Embase.
Eligibility criteria for selecting studies: Prospective cohort studies with relative risks and 95% CIs for type 2 diabetes according to the intake of fruit, vegetables, or fruit and vegetables.
Results: A total of 10 articles including 13 comparisons with 24,013 cases of type 2 diabetes and 434,342 participants were included in the meta-analysis. Evidence of curve linear associations was seen between fruit and green leafy vegetables consumption and risk of type 2 diabetes (p=0.059 and p=0.036 for non-linearity, respectively). The summary relative risk of type 2 diabetes for an increase of 1 serving fruit consumed/day was 0.93 (95% CI 0.88 to 0.99) without heterogeneity among studies (p=0.477, I(2)=0%). For vegetables, the combined relative risk of type 2 diabetes for an increase of 1 serving consumed/day was 0.90 (95% CI 0.80 to 1.01) with moderate heterogeneity among studies (p=0.002, I(2)=66.5%). For green leafy vegetables, the summary relative risk of type 2 diabetes for an increase of 0.2 serving consumed/day was 0.87 (95% CI 0.81 to 0.93) without heterogeneity among studies (p=0.496, I(2)=0%). The combined estimates showed no significant benefits of increasing the consumption of fruit and vegetables combined.
Conclusions: Higher fruit or green leafy vegetables intake is associated with a significantly reduced risk of type 2 diabetes.
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