Type-1 diabetes happens when the immune system weakens the body's ability to produce insulin. and vitamin D is thought to keep the immune system healthy.
Researchers compiled data from five studies on the effects of vitamin D. They found that children who took vitamin D supplements were 30 percent less likely to develop type-1 diabetes than those who did not take it. They also found higher doses of the supplement also reduced the risk of developing the disease.
You can learn more about the study in the journal Archives of Disease in Childhood.