Circulating levels of vitamin D, vitamin D receptor polymorphisms, and colorectal adenoma: a meta-analysis

Abstract

Growing evidence suggests an elevated risk for colorectal neoplasia among individuals with low levels of vitamin D, the biological actions of which are mediated by the vitamin D receptor (VDR). To investigate the association among vitamin D status, VDR polymorphisms (FokI, and BsmI), and colorectal adenoma, we conducted a meta-analysis of nine studies of circulating levels of 25-hydroxyvitamin D (25(OH)D) and five studies of FokI or BsmI polymorphisms in relation to colorectal adenomas. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were pooled using a random-effects model. A total of 3398 colorectal adenomas for 25(OH)D and 1754 colorectal adenomas for VDR were included in the meta-analysis. We identified a significant inverse association between colorectal adenoma (combined RR, 0.93; 95% CI, 0.87-0.98 per 10 ng/mL increase in 25(OH)D levels). When we examined FokI and BsmI polymorphisms in the meta-analysis, we found no association for either FokI (combined RR, 1.00; 95% CI, 0.95-1.06) or BsmI (combined RR, 0.99; 95% CI, 0.93-1.05) in the additive model. These data suggest an inverse association between circulating 25(OH)D levels and colorectal adenoma risk.

Keywords: 25-hydroxyvitamin D; Colorectal adenoma; meta-analysis; vitamin D receptor.

Fig. 1

Study-specific and combined relative risks (RRs) and 95% confidence intervals (CIs) of colorectal adenoma per 10 ng/mL increase in blood 25(OH)D levels. Black circles indicate the study-specific relative risks; horizontal lines represent the 95% CIs. The area of the gray squares reflects the study-specific weights (inverse of the variance). The dashed line represents the combined RR and the diamond represents the 95% CI for the combined RR.

Fig. 2

Study-specific and combined relative risks (RRs) and 95% confidence intervals (CIs) for colorectal adenoma according to FokI and BsmI polymorphisms in the additive model. Black circles indicate study-specific odds ratios; horizontal lines represent the 95% CIs. The area of the gray squares reflects the study-specific weights (inverse of the variance). The dashed line represents the combined RR and the diamond represents the 95% CI for the combined RR.