Vitamin D status and vitamin D receptor genotypes in celiac disease: a meta-analysis

Background:There have been various articles reporting relationship between Vitamin D (VitD) and celiac disease (CeD), but results remain controversial. This study aimed to conduct a meta-analysis to systematically review and quantify the relationship between VitD and CeD. Moreover, difference in Vitamin D Receptor (VDR) genotypes between CeD patients and controls was also analyzed. Methods:Articles published until July 20, 2019 in the PubMed, MEDLINE, and EMBASE databases were searched. According to the inclusion and exclusion criteria, relevant statistical data were collated and extracted, which were finally analyzed by STATA15.1. Results:27 articles and 28 sets of data were included. It showed that average 25(OH)D level in CeD patients was 8.36 nmol/L lower than controls (Weighted Mean Difference (WMD) = -8.36, 95% CI = [-14.63, -2.09] nmol/L). After gluten-free diet treatment, we found that average 25(OH)D level in treated patients was 15.6 nmol/L higher than untreated patients (WMD = 15.6, 95% CI = [5.96, 25.23] nmol/L). In addition, 25(OH)D level in treated patients was close to healthy controls (WMD = -2.82, 95% CI = [-6.45, 0.73] nmol/L). However, genetic polymorphism analysis showed that there is no difference in VDR genotypes between CeD and control. Conclusions:CeD had decreased serum 25(OH)D levels, which returned to normal after treatment, suggesting that VitD may play a role in the development of CeD. The directionality of this association cannot be confirmed from cross-sectional studies. Demonstration of a causal role of VitD deficiency in CeD development in future studies could have important therapeutic implications.