Fruit and vegetable intake and incidence of type 2 diabetes mellitus: systematic review and meta-analysis.

OBJECTIVE: To investigate the independent effects of intake of fruit and vegetables on incidence of type 2 diabetes. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Medline, Embase, CINAHL, British Nursing Index (BNI), and the Cochrane library were searched for medical subject headings and keywords on diabetes, prediabetes, fruit, and vegetables. Expert opinions were sought and reference lists of relevant articles checked. STUDY SELECTION: Prospective cohort studies with an independent measure of intake of fruit, vegetables, or fruit and vegetables and data on incidence of type 2 diabetes. RESULTS: Six studies met the inclusion criteria; four of these studies also provided separate information on the consumption of green leafy vegetables. Summary estimates showed that greater intake of green leafy vegetables was associated with a 14% (hazard ratio 0.86, 95% confidence interval 0.77 to 0.97) reduction in risk of type 2 diabetes (P=0.01). The summary estimates showed no significant benefits of increasing the consumption of vegetables, fruit, or fruit and vegetables combined. CONCLUSION: Increasing daily intake of green leafy vegetables could significantly reduce the risk of type 2 diabetes and should be investigated further.