Abstract: Vitamin D is suggested to have protective effects against type 1 diabetes. However, the results from observational studies have been inconsistent. We aimed to examine their association by conducting a meta-analysis of observational studies. Multiple databases were searched in June 2013 to identify relevant studies including both case-control and cohort studies. Either a fixed- or random-effects model was used to calculate the pooled risk estimate. We identified eight studies (two cohort studies and six case-control studies) on vitamin D intake during early life and three studies (two cohort studies and one case-control study) on maternal vitamin D intake during pregnancy. The pooled odds ratio for type 1 diabetes comparing vitamin D supplementation with non-supplementation during early life was 0.71 (95% confidence interval [CI], 0.51–0.98). Similar results were observed in the case-control subgroup analysis but not in the cohort subgroup analysis. The pooled odds ratio with maternal intake of vitamin D during pregnancy was 0.95 (95% CI, 0.66–1.36). In conclusion, vitamin D intake during early life may be associated with a reduced risk of type 1 diabetes. However, there was not enough evidence for an association between maternal intake of vitamin D and risk of type 1 diabetes in the offspring.
Keywords: vitamin D; type 1 diabetes; early life; pregnancy; meta-analysis
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Dong, J.-Y.; Zhang, W.; Chen, J.J.; Zhang, Z.-L.; Han, S.-F.; Qin, L.-Q. Vitamin D Intake and Risk of Type 1 Diabetes: A Meta-Analysis of Observational Studies. Nutrients 2013, 5, 3551-3562.
Dong J-Y, Zhang W, Chen JJ, Zhang Z-L, Han S-F, Qin L-Q. Vitamin D Intake and Risk of Type 1 Diabetes: A Meta-Analysis of Observational Studies. Nutrients. 2013; 5(9):3551-3562.
Dong, Jia-Yi; Zhang, Weiguo; Chen, Jiong J.; Zhang, Zeng-Li; Han, Shu-Fen; Qin, Li-Qiang. 2013. "Vitamin D Intake and Risk of Type 1 Diabetes: A Meta-Analysis of Observational Studies." Nutrients 5, no. 9: 3551-3562.