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Does Early Vitamin D Supplementation Prevent Type 1 Diabetes?

Findings from a meta-analysis suggest that vitamin D supplementation in infancy lowers risk for developing type 1 diabetes.

Vitamin D supplementation has been associated with protection against development of type 1 diabetes mellitus. U.K. investigators conducted a systematic review and meta-analysis (based on 1 cohort study and 4 case-control studies involving 1429 cases and 5026 healthy controls) in which they compared risk for type 1 diabetes among people who did or did not receive supplemental vitamin D during infancy. The methodologic quality of all five of these European retrospective studies was rated as moderate.

In the meta-analysis, infants who received vitamin D supplementation were significantly less likely than those who did not receive it to have developed diabetes by 15 to 30 years of age (odds ratio, 0.71). When cod liver oil was the source of vitamin D, more-frequent supplementation was related to lower risk (OR, 0.81 for 1–4 times weekly; OR, 0.74 for 5 times weekly). Frequency of other types of vitamin D supplementation had a negligible effect on risk. In the cohort study, regular doses of vitamin D (2000 IU) were associated with significantly lower risk for diabetes than were smaller doses (OR, 0.22). In one study, in which timing of supplementation was evaluated, infants who began supplementation between ages 7 and 12 months had lower risk for diabetes later in life than those who began supplementation before age 6 months. Finally, in one study, duration of supplementation for less than or more than 1 year lowered risk by similar amounts.

Comment: These findings suggest that vitamin D supplementation during infancy lowers risk for developing type 1 diabetes. Limitations include the retrospective nature of the studies, recall bias, failure to document vitamin D levels before or after supplementation, and heterogeneity of types of supplements evaluated. Nonetheless, dietary vitamin D supplementation can be recommended for many reasons, including bone health and, now, diabetes prevention. A prospective study is required to clarify the magnitude and mechanism of vitamin D’s influence on the underlying genetic propensity for type 1 diabetes. The AAP guideline states that all infants who receive <500 mL of vitamin D–fortified formula daily (i.e., breast-fed infants) should receive 200 IU of vitamin D daily.

— F. Bruder Stapleton, MD

Published in Journal Watch Pediatrics and Adolescent Medicine April 23, 2008

Citation(s):

Zipitis CS and Akobeng AK. Vitamin D supplementation in early childhood and risk of type 1 diabetes: A systematic review and meta-analysis. Arch Dis Child 2008 Mar 13; [e-pub ahead of print]. (http://dx.doi.org/10.1136/adc.2007.128579)