The Effect of Fruit and Vegetable Intake on the Incidence of Diabetes

STUDY

Carter P, Gray LJ, Troughton J, Khunti K, Davies MJ: Fruit and vegetable intake and incidence of type 2 diabetes mellitus: systematic review and meta-analysis. BMJ 341:c422, 2010

SUMMARY

Design. Systematic review and meta-analysis.

Subjects. Six prospective cohort studies with 223,412 total participants were performed; only two studies included men. The mean age of participants ranged from 30 to 74 years. Study length ranged from 4.6 to 23 years (median length was 13.4 years). All studies included an individual measure of fruits, vegetables, or combined fruit and vegetable intake. Three provided information on fruit and vegetable intake separately and combined; two provided information on fruit and vegetable intake separately only; and one study provided only combined data. Four studies also included separate data on the intake of green leafy vegetables.

Methods. Investigators calculated summary hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of type 2 diabetes for the highest versus lowest quintiles of intake of fruit and/or vegetable consumption. HRs or relative risks from each study were pooled to give a summary estimate of risk using a random effects model. Investigators assessed for heterogeneity among studies' estimated effects using the I² statistic. Two reviewers independently assessed all potentially relevant studies for inclusion and assessed the methodological quality of each included study.

Results. The number of incident type 2 diabetes cases ranged from 383 to 4,529 across the six studies. The meta-analysis of highest versus lowest quintiles of intake of fruit and vegetables did not identify statistically significant reductions in risk of type 2 diabetes incidence for consumption of fruit, vegetables, or fruit and vegetables combined. The pooled HRs were 0.93 (95% CI 0.83–1.01) for …