Fruit and vegetable intake and incidence of type 2 diabetes mellitus: systematic review and meta-analysisBMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c4229 (Published 19 August 2010) Cite this as: BMJ 2010;341:c4229
- Patrice Carter, research nutritionist1,
- Laura J Gray, research associate in medical statistics2,
- Jacqui Troughton, senior research associate3,
- Kamlesh Khunti, professor of primary care diabetes and vascular medicine2,
- Melanie J Davies, professor of diabetes medicine1
- 1Diabetes Research, Department of Cardiovascular Sciences, University of Leicester, Leicester LE1 5WW
- 2Clinical Division of General Practice and Primary Health Sciences, University of Leicester, Leicester LE1 7RH
- 3Diabetes Research Department, University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester LE1 5WW
- Correspondence to: P Carter, University of Leicester, Diabetes Research Team, Level 6, Windsor Building, Leicester Royal Infirmary, Leicester LE1 5WW
- Accepted 28 June 2010
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.
We thank Nita Forouhi from the Medical Research Council Epidemiology Unit, Institute of Metabolic Science, Cambridge, for her detailed contribution and advice. We also thank Sarah Sutton, clinical librarian, and Janette Camosso-Stefinovic, information librarian, for their input to the search strategy.
Contributors: PC, KK, and MJD had the original idea for the review. KK and MJD developed the search protocol for the review with PC. PC performed the literature review, extracted and analysed data, and wrote the first draft of the article. JT also reviewed, extracted, and analysed data. LJG performed the statistical analysis. All authors contributed to the writing of the paper and gave input at all stages of the study. PC is guarantor.
Funding and study sponsor: The research was funded by the Cardiovascular Research Department, University of Leicester. PC is being funded for a PhD in the department. All members of the research team are either employees of the University of Leicester or the University Hospitals of Leicester NHS Trust. We acknowledge ongoing support from NIHR-CLAHRC.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that (1) no financial support for the submitted work from anyone other than their employer; (2) no financial relationships with commercial entities that might have an interest in the submitted work in the previous 3 years; (3) no spouses, partners, or children with relationships with commercial entities that may be relevant to the submitted work; and (4) KK and MJD have received grants from the National Institute of Health Research (NIHR) for studies on the prevention of type 2 diabetes.
Ethical approval: Not required.
Data sharing: Dataset available from the corresponding author.
- Accepted 28 June 2010
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