Vitamin D intake, serum Vitamin D levels, and risk of gastric cancer: A systematic review and meta-analysis

Background: We are aware of no systematic review or meta-analysis of published findings about the association between Vitamin D status and risk of gastric cancer (GC). We systematically reviewed the current evidence on the association between Vitamin D intake as well as serum 25-hydroxy Vitamin D (25(OH)D) levels and risk of GC. Materials and Methods: Published evidence in this area was searched to August 2014 through the use of ISI Web of Science, Scopus, PubMed/Medline, Ovid Database, EMBASE, and Google Scholar for relevant articles by cross-referencing. Seven articles had reported odds ratios (ORs) or relative risks (RR) as their effect size; four papers had reported the ORs between Vitamin D intake and GC; and three papers had reported the association between serum 25(OH)D and risk of GC. Results: Pooled effect size for comparison of highest versus lowest intakes of Vitamin D was 1.09 (95% confidence interval [CI]: 0.94, 1.25; P = 0.26) indicating no significant association between Vitamin D intake and risk of GC. We failed to find a significant association between serum Vitamin D levels and risk of GC (OR: 0.92; 95% CI: 0.74-1.14; P = 0.429). Among men, the pooled effect size or highest versus lowest category of serum Vitamin D levels was 0.92 (95% CI: 0.71, 1.18, P = 0.49). The corresponding figures in women were 1.04 and 95% CI: 0.74-1.47 (P = 0.80). Conclusion: We found no evidence for the significant association between Vitamin D status and risk of GC. However, due to limited data in this field, further studies are required to reach a definite conclusion.