A study at Harvard concludes that having adequate amounts of Vitamin D during adulthood reduces the risk of type 1 diabetes.

A new study conducted by researchers at the Harvard School of Public Health suggests that vitamin intake may play a significant role in cases of adult-onset type 1 diabetes, a disease commonly associated with genetic factors.

The study, which will be published in the American Journal of Epidemiology, found that young adults who maintain sufficient levels of Vitamin D can reduce their risk of adult-onset type 1 diabetes by 50 to 60 percent.

Although most previous type 1 diabetes studies have investigated childhood onset, senior author and School of Public Health professor Alberto Ascherio said that patients diagnosed later in life are more likely to have been affected by environmental factors.

The researchers analyzed blood samples of active military members taken from the Department of Defense Serum Repository, comparing diabetes patients’ blood samples taken prior to disease onset with samples taken from a control group.

Although the study found that the risk of adult-onset type 1 diabetes may be significantly reduced if vitamin D levels are at least 75 nanomoles per liter, lead author and School of Public Health research associate Kassandra Munger said the results are only conclusive for non-Hispanic white males.

“We didn’t see an association in non-Hispanic Blacks or Hispanics, possibly due to the smaller sample size,” Munger said. “We also can’t say for sure that the same results would be seen in women.”

The research group decided to study the effects of Vitamin D on type 1 diabetes after previously finding a strong association between Vitamin D levels and multiple sclerosis.

Bruce W. Hollis, professor of pediatrics at the Medical University of South Carolina, said that the consistent results of both studies provides strong evidence that adequate Vitamin D levels can contribute to disease prevention.

“Multiple sclerosis and type 1 diabetes are both autoimmune disorders, and the studies basically showed the same thing,” said Hollis. “The papers have shown that you need to take three to four thousand units per day to attain appropriate blood levels to prevent diseases.”

Although additional studies are necessary before any formal recommendations for Vitamin D supplementation are made, researchers stressed the importance of achieving high Vitamin D levels.

In addition to food sources, Hollis said that one of the easiest ways to achieve these Vitamin D levels is to get sun exposure. Spending 20 minutes outside during peak sun hours releases about 20,000 units of Vitamin D into the bloodstream within 24 hours, he said.

The researchers hope to expand their studies in the future.

“I hope to study several hundred cases, study a larger sample size that includes women, and look at finer points of association,” Munger said.

—Staff writer Michelle S. Lee can be reached at mlee03@college.harvard.edu.