Association between vitamin C Intake and the risk of cervical neoplasia: A meta-analysis

To assess the association between vitamin C intake and cervical neoplasia (CN) risk. Databases including PubMed, Embase, and Springer link were retrieved up to June 10, 2014 with predefined strategy. The combined odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for overall and subgroup analyses. The publication bias was assessed using Begg's test and Egger's test. Sensitivity analysis was also conducted. Twelve studies consisting of 1 prospective cohort study and 11 case-control studies were included. In overall analysis, vitamin C intake was significantly associated with the reduced risk of CN (OR = 0.58; 95% CI: 0.44 to 0.75; P < 0.001). Subgroup analysis stratified by vitamin C dose indicated all dose categories achieved a reduced CN risk. Furthermore, increased vitamin C intake by 50 mg/day was related to the reduced risk of CN (OR = 0.92; 95% CI: 0.89 to 0.94; P < 0.05). No publication bias was detected by Begg's test (P = 0.169) and no apparent fluctuation was observed in summary OR by sensitivity analysis. Vitamin C intake was inversely associated with the risk of CN and this association was dose-dependent. However, more randomized controlled trials are required for further validation.