A new study, published this week in the journal Diabetologia, shows a correlation between the incidence of Type 1 diabetes and vitamin D3 serum levels. The study used samples from the U.S. Department of Defense Serum Repository, which stores more than 50 million serum samples for disease surveillance.

“Previous studies proposed the existence of an association between vitamin D deficiency and risk of and Type 1 diabetes, but this is the first time that the theory has been tested in a way that provides the dose-response relationship,” said Dr. Cedric Garland, lead author of the study and professor at the University of California at San Diego’s Department of Family and Preventive Medicine.

Researchers thawed 2000 serum samples, half of which were from people who later developed type 1 diabetes. By comparing serum concentrations of Vitamin D, they were able to determine the optimal serum level needed to lower an individual’s risk of developing type 1 diabetes. Garland estimates that 50 ng/ml of the predominantly circulating form of vitamin D is needed to cut the risk.

“While there are a few conditions that influence vitamin D metabolism, for most people, 4000 IU per day of vitamin D3 will be needed to achieve the effective levels,” said Garland. “This beneficial effect is present at these intakes only for vitamin D3. Reliance should not be placed on different forms of vitamin D and mega doses should be avoided, as most of the benefits for prevention of disease are for doses less than 10,000 IU/day.”

Garland cautioned that patients should consult their doctor before increading their D3 intake.