Fruit and vegetable consumption and the risk of type 2 diabetes: a systematic review and dose–response meta-analysis of prospective studies

BACKGROUND: The association between intake of fruit and vegetables and their subtypes, and the risk of type 2 diabetes has been investigated in several studies, but the results have been inconsistent. OBJECTIVE: We conducted an updated systematic review and dose–response meta-analysis of prospective studies on intakes of fruit and vegetables and fruit and vegetable subtypes and the risk of type 2 diabetes. DESIGN: PubMed and Embase databases were searched up to 20 October 2020. Prospective cohort studies of fruit and vegetable consumption and type 2 diabetes mellitus were included. Summary relative risks (RRs) and 95% CIs were estimated using a random effects model. RESULTS: We included 23 cohort studies. The summary RR for high versus low intake and per 200 g/day were 0.93 (95% CI: 0.89 to 0.98, I(2)=0%, n=10 studies) and 0.98 (95% CI: 0.95 to 1.01, I(2)=37.8%, n=7) for fruit and vegetables combined, 0.93 (95% CI: 0.90 to 0.97, I(2)=9.3%, n=20) and 0.96 (95% CI: 0.92 to 1.00, I(2)=68.4%, n=19) for fruits and 0.95 (95% CI: 0.88 to 1.02, I(2)=60.4%, n=17) and 0.97 (95% CI: 0.94 to 1.01, I(2)=39.2%, n=16) for vegetables, respectively. Inverse associations were observed for apples, apples and pears, blueberries, grapefruit and grapes and raisins, while positive associations were observed for intakes of cantaloupe, fruit drinks, fruit juice, brussels sprouts, cauliflower and potatoes, however, most of these associations were based on few studies and need further investigation in additional studies. CONCLUSIONS: This meta-analysis found a weak inverse association between fruit and vegetable intake and type 2 diabetes risk. There is indication of both inverse and positive associations between intake of several fruit and vegetables subtypes and type 2 diabetes risk, however, further studies are needed before firm conclusions can be made.