title: Intake of fruit and vegetables and risk of bladder cancer: a dose-response meta-analysis of observational studies.
abstract: BACKGROUND
  Observational studies suggest an association between fruit and vegetables intake and risk of bladder cancer, but the results are controversial.
  
  
  METHODS
  We therefore summarized the evidence from observational studies in categorical, linear, and nonlinear, dose-response meta-analysis. Pertinent studies were identified by searching EMBASE and PubMed from their inception to August 2013.
  
  
  RESULTS
  Thirty-one observational studies involving 12,610 cases and 1,121,649 participants were included. The combined rate ratio (RR, 95 % CI) of bladder cancer for the highest versus lowest intake was 0.83 (0.69-0.99) for total fruit and vegetables, 0.81 (0.70-0.93) for total vegetables, 0.77 (0.69-0.87) for total fruit, 0.84 (0.77-0.91) for cruciferous vegetables, 0.79 (0.68-0.91) for citrus fruits, and 0.74 (0.66-0.84) for yellow-orange vegetables. Subgroup analysis showed study design and gender as possible sources of heterogeneity. A nonlinear relationship was found of citrus fruits intake with risk of bladder cancer (P for nonlinearity = 0.018), and the RRs (95 % CI) of bladder cancer were 0.87 (0.78-0.96), 0.80 (0.67-0.94), 0.79 (0.66-0.94), 0.79 (0.65-0.96), and 0.79 (0.64-0.99) for 30, 60, 90, 120, and 150 g/day. A nonlinear relationship was also found of yellow-orange vegetable intake with risk of bladder cancer risk (P for nonlinearity = 0.033). Some evidence of publication bias was observed for fruit, citrus fruits, and yellow-orange vegetables.
  
  
  CONCLUSIONS
  This meta-analysis supports the hypothesis that intakes of fruit and vegetables may reduce the risk of bladder cancer. Future well-designed studies are required to confirm this finding.
authors.affiliation: Shanghai Minhang Center for Disease Control and Prevention, 965 Zhongyi Road, Shanghai, 201101, China.
authors.forename: Baodong
authors.initials: B
authors.lastname: Yao
authors.forename: Yujie
authors.initials: Y
authors.lastname: Yan
authors.forename: Xianwu
authors.initials: X
authors.lastname: Ye
authors.forename: Hong
authors.initials: H
authors.lastname: Fang
authors.forename: Huilin
authors.initials: H
authors.lastname: Xu
authors.forename: Yinan
authors.initials: Y
authors.lastname: Liu
authors.forename: Sheran
authors.initials: S
authors.lastname: Li
authors.forename: Yanping
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D004032:Diet; D004305:Dose-Response Relationship, Drug; D005638:Fruit; D006801:Humans; D064887:Observational Studies as Topic; D012307:Risk Factors; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D014675:Vegetables