The study, which was published in the American Journal of Epidemiology, is the strongest one to date to provide evidence that vitamin D may be protective against type 1 diabetes. According to lead author Kassandra Munger, research associate in the Department of Nutrition at HSPH, ‘It is surprising that a serious disease such as type 1 diabetes could perhaps be prevented by a simple and safe intervention.’
For their study, the researchers examined the blood samples of US military personnel on active duty. These samples were attained from the Department of Defence Serum Repository, which contains more than 40 million samples collected from 8 million military personnel since the mid-1980s. The team identified 310 individuals whose wellness had been affected by type 1 diabetes between 1997 and 2009, and compared their samples with those of 613 people in a control group.
The results showed that white, non-Hispanic, healthy young adults with higher serum levels (>75 nmol/L) of vitamin D had about half the risk of developing type 1 diabetes than those with the lowest levels of vitamin D (<75 nmol/L). There was no significant association found among Hispanics and blacks, but the authors said this may be due to the small number of individuals in these groups.
Alberto Ascherio, professor of epidemiology and nutrition at HSPH and the study’s senior author, commented, ‘The risk of type 1 diabetes appears to be increased even at vitamin D levels that are commonly regarded as normal, suggesting that a substantial proportion of the population could benefit from increased vitamin D intake.’ However, the authors added, ‘Whereas it is premature to recommend universal use of vitamin D supplements for prevention of type 1 diabetes, the possibility that many cases could be prevented by supplementation with 1,000-4,000 IU/day, which is largely considered safe, is enticing.’