Meta-analysis: Serum vitamin D and colorectal adenoma risk.

Objective: To perform a systematic review and meta-analysis of human studies on the association between serum 25 hydroxyvitamin D (25(OH)D) and incident, sporadic colorectal adenoma (CRA) and CRA recurrence.

Methods: Relevant studies among humans were identified by systematically searching Ovid Medline, EMBASE, and ISI Web of Knowledge databases and by cross-referencing. Due to the heterogeneity across studies in categorizing serum vitamin D levels, all results were recalculated for an increase of serum 25(OH)D by 20 ng/ml. Summary odds ratios (ORs) were calculated using meta-analysis methods.

Results: Overall, 10 original studies were included. Specific results for incident CRA according to serum 25(OH)D were reported in 8 studies, and for CRA recurrence in 2 studies, respectively. In meta-analyses, summary ORs (95% confidence intervals) regarding incident and recurrent CRA, and both outcomes combined were 0.82 (0.69-0.97), 0.87 (0.56-1.35), and 0.84 (0.72-0.97), respectively, for an increase of 25(OH)D by 20 ng/ml. No publication bias was found.

Conclusion: Our results support suggestions that serum 25(OH)D levels are inversely associated with CRA risk.