Environmental Factors in Type 1 Diabetes.

The contribution of environmental factors to the pathogenesis of type 1 diabetes is considered substantial, but their identification has turned out to be challenging. Large prospective studies are crucial for reliable identification of environmental risk and protective factors. However, only few large prospective birth cohort studies have been carried out. Enterovirus infections have shown quite consistent risk association with the initiation of islet autoimmunity (IA) across these studies. Also, certain dietary factors have been consistently associated with IA risk, omega-3 fatty acids inversely, and childhood cow's milk intake directly. However, the mechanisms of these associations are not fully understood, and possible causality has not been confirmed. Clinical trial programs with enterovirus vaccines and antiviral drugs are in progress to evaluate the causality of enterovirus association. The only nutritional primary prevention randomized trial, TRIGR, did not find a difference between weaning to extensively hydrolyzed versus conventional cow's milk-based infant formula.