Vitamin C Intake and Pancreatic Cancer Risk: A Meta-Analysis of Published Case-Control and Cohort Studies

PLoS One. 2016 Feb 9;11(2):e0148816. doi: 10.1371/journal.pone.0148816. eCollection 2016.

Abstract

Background: Observational studies inconsistently reported the relationship between vitamin C intake and risk of pancreatic cancer. We conducted a meta-analysis of published case-control and cohort studies to quantify the association.

Methods: Potentially eligible studies were found on PubMed and EMBASE databases through May 31, 2015. A random-effects model was assigned to compute summary point estimates with corresponding 95% confidence intervals (CIs). Subgroup and meta-regression analyses were also performed to explore sources of heterogeneity.

Results: Our final analyses included 20 observational studies comprising nearly 5 thousand cases of pancreatic cancer. When comparing the highest with the lowest categories of vitamin C intake, the summary odds ratio/relative risk for case-control studies (14 studies), cohort studies (6 studies) and all studies combined was 0.58 (95% CI: 0.52-0.66), 0.93 (95% CI: 0.78-1.11) and 0.66 (95% CI: 0.58-0.75), respectively. The difference in the findings between case-control and cohort studies was statistically significant (P < .001). Possible publication bias was shown in the meta-analysis of case-control studies.

Conclusion: There is insufficient evidence to conclude any relationship between vitamin C intake and risk of pancreatic cancer. The strong inverse association observed in case-control studies may be affected by biases (eg, recall and selection biases) that particularly affect case-control studies and/or potential publication bias. Future prospective studies of vitamin C intake and pancreatic cancer are needed.

Publication types

  • Meta-Analysis

MeSH terms

  • Antioxidants / administration & dosage*
  • Antioxidants / therapeutic use
  • Ascorbic Acid / administration & dosage*
  • Ascorbic Acid / therapeutic use
  • Case-Control Studies
  • Cohort Studies
  • Humans
  • Pancreatic Neoplasms / epidemiology*
  • Pancreatic Neoplasms / prevention & control
  • Risk

Substances

  • Antioxidants
  • Ascorbic Acid

Grants and funding

The authors have no support or funding to report.