Circulating levels of vitamin D and colorectal adenoma: A case-control study and a meta-analysis

AIM: To examine the association between circulating 25-hydroxyvitamin D [25(OH) D] levels and colorectal adenoma in a case-control study and a meta-analysis. METHODS: We conducted a matched case-control study (112 cases and 112 matched controls) and combined 15 studies, including our study, in a metaanalysis. The study-specific odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using a randomeffects model. In total, 5454 colorectal adenomas and 6656 controls were included in the meta-analysis. RESULTS: In a meta-analysis including 14 previous studies and our study, we observed a significant inverse association between circulating 25(OH) D levels and colorectal adenoma (OR = 0.68; 95% CI: 0.54-0.82) when comparing the highest category with the lowest category. Stratification by adenoma location (proximal or distal adenoma) showed similar estimates. When we stratified by study region, the ORs (95% CIs) were 0.70 (0.52-0.88) in the US and 0.66 (0.34-0.97) in Asia. CONCLUSION: These data suggest an inverse association between circulating 25(OH) D levels and colorectal adenoma in both Western and Asian populations.