Fruit and vegetable consumption and risk of type 2 diabetes mellitus: a dose-response meta-analysis of prospective cohort studies

Abstract

Background and aims: We conducted a dose-response meta-analysis to summarize the evidence from prospective cohort studies regarding the association of fruit and vegetable consumption with risk of type 2 diabetes mellitus (T2DM).

Methods and results: Pertinent studies were identified by searching Embase and PubMed through June 2014. Study-specific results were pooled using a random-effect model. The dose-response relationship was assessed by the restricted cubic spline model and the multivariate random-effect meta-regression. We standardized all data using a standard portion size of 106 g. The Relative Risk (95% confidence interval) [RR (95% CI)] of T2DM was 0.99 (0.98-1.00) for every 1 serving/day increment in fruit and vegetable (FV) (P = 0.18), 0.98 (0.95-1.01) for vegetable (P = 0.12), and 0.99 (0.97-1.00) for fruit (P = 0.05). The RR (95%CI) of T2DM was 0.99 (0.97-1.01), 0.98 (0.96-1.01), 0.97 (0.93-1.01), 0.96 (0.92-1.01), 0.96 (0.91-1.01) and 0.96 (0.91-1.01) for 1, 2, 3, 4, 5 and 6 servings/day of FV (P(for non-linearity) = 0.44). The T2DM risk was 0.96 (0.95-0.99), 0.94 (0.90-0.98), 0.94 (0.89-0.98), 0.96 (0.91-1.01), 0.98 (0.92-1.05) and 1.00 (0.93-1.08) for 1, 2, 3, 4, 5 and 6 servings/day of vegetable (P(for non-linearity) < 0.01). The T2DM risk was 0.95 (0.93-0.97), 0.91 (0.89-0.94), 0.88 (0.85-0.92), 0.92 (0.88-0.96) and 0.96 (0.92-1.01) for 0.5, 1, 2, 3 and 4 servings/day of fruit (P(for non-linearity) < 0.01).

Conclusions: Two-three servings/day of vegetable and 2 servings/day of fruit conferred a lower risk of T2DM than other levels of vegetable and fruit consumption, respectively.

Keywords: Dose-response meta-analysis; Fruit; Prospective cohort studies; Type 2 diabetes mellitus; Vegetable.