PT  - JOURNAL ARTICLE
AU  - C S Zipitis
AU  - A K Akobeng
TI  - Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis
AID  - 10.1136/adc.2007.128579
DP  - 2008 Jun 01
TA  - Archives of Disease in Childhood
PG  - 512--517
VI  - 93
IP  - 6
4099  - http://adc.bmj.com/content/93/6/512.short
4100  - http://adc.bmj.com/content/93/6/512.full
SO  - Arch Dis Child2008 Jun 01; 93
AB  - Objectives: To assess whether vitamin D supplementation in infancy reduces the risk of type 1 diabetes in later life.Methods: This was a systematic review and meta-analysis using Medline, Embase, Cinahl, Cochrane Central Register of Controlled Trials and reference lists of retrieved articles. The main outcome measure was development of type 1 diabetes. Controlled trials and observational studies that had assessed the effect of vitamin D supplementation on risk of developing type 1 diabetes were included in the analysis.Results: Five observational studies (four case-control studies and one cohort study) met the inclusion criteria; no randomised controlled trials were found. Meta-analysis of data from the case-control studies showed that the risk of type 1 diabetes was significantly reduced in infants who were supplemented with vitamin D compared to those who were not supplemented (pooled odds ratio 0.71, 95% CI 0.60 to 0.84). The result of the cohort study was in agreement with that of the meta-analysis. There was also some evidence of a dose-response effect, with those using higher amounts of vitamin D being at lower risk of developing type 1 diabetes. Finally, there was a suggestion that the timing of supplementation might also be important for the subsequent development of type 1 diabetes.Conclusion: Vitamin D supplementation in early childhood may offer protection against the development of type 1 diabetes. The evidence for this is based on observational studies. Adequately powered, randomised controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.