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Vitamin D has been shown to help regulate the body’s immune system. FreshSplash/Getty Images
  • Autoimmune diseases such as rheumatoid arthritis and multiple sclerosis occur when the immune system mistakenly attacks the body.
  • New research indicates that vitamin D supplements may help prevent autoimmune diseases.
  • Experts say the latest study provides valuable information on using vitamin D to lower the risk of autoimmune diseases.
  • They add that more research with more diverse populations is needed, though.

A new study published in The BMJ reports that vitamin D supplementation over a period of 5 years reduced autoimmune diseases by 22 percent.

“This study of more than 25,000 older adults in the U.S. provides evidence that daily supplementation with 2,000 IU/day vitamin D or a combination of vitamin D and omega 3 fatty acids for five years reduces autoimmune disease incidence, with more pronounced effects found after two years of supplementation,” the study authors wrote.

“The clinical importance of these findings is high because these are well tolerated, non-toxic supplements, and other effective treatments to reduce the incidence of autoimmune diseases are lacking. Additionally, we saw consistent results across autoimmune diseases and increasing effects with time,” the researchers added.

Autoimmune diseases are conditions in which the immune system mistakenly attacks the body. These diseases include rheumatoid arthritis (RA), lupus, and multiple sclerosis (MS).

More than 24 million people in the United States live with an autoimmune disease.

Another 8 million people have autoantibodies in their blood, which indicates they have a chance of developing an autoimmune disease.

The exact causes of autoimmune diseases remain unknown, but they are likely due to a combination of factors.

“We think that autoimmune diseases develop in patients who have a genetic susceptibility to autoimmunity. And then there’s things that happen in the environment that probably trigger the autoimmune disease to develop,” Dr. Elizabeth Volkmann, the director of the UCLA Scleroderma Program, told Healthline.

Volkmann said the research published in BMJ is a landmark study in the area of autoimmune disease prevention.

“It was one of the first studies to look at the primary prevention of autoimmune disease using vitamin D supplementation,” she said.

“There’s been a number of observational studies that have demonstrated that low vitamin D is associated with certain autoimmune diseases. And there’s even been some studies looking at vitamin D supplementation as a treatment for autoimmune disease. But there’s been very few studies that have looked at it as a tool for preventing the onset of autoimmune disease,” she explained.

Dr. Marilyn Tan, a clinical associate professor of medicine at Stanford University in California, said the findings of the study are promising.

“There really isn’t a lot pharmacologically that we can strongly recommend for disease prevention. In these cases, certainly, we talk about stress reduction and living a healthy lifestyle and all of that to try to prevent any worsening of autoimmune disease. But there really isn’t a medicine that has been proven to decrease the progression,” Tan told Healthline.

“Can we say that it’s definitively going to reduce your risk of progression to autoimmune disease? I think that’s difficult to say,” she said.

“But at the same time, it’s very unlikely to do any harm,” Tan added. “And in addition to that, there are other benefits to vitamin D. So, for example, helping with osteoporosis risk and your bone health. And then on the other hand… inflammatory and autoimmune disease can sometimes increase osteoporosis risk. And so for that, the vitamin D, the extra vitamin D may even help as well.”

Previous research suggests vitamin D can help regulate genes that play a role in both inflammation and immunity.

But experts say more research across broader populations needs to be undertaken to confirm if vitamin D reduces autoimmune risk in different groups.

“This study provides some nice evidence that vitamin D supplementation may prevent the development of autoimmune disease, but specifically in this… population of patients, so patients over the age of 50 or 55,” Volkmann said.

“The majority of autoimmune diseases occur in women of childbearing age, so much younger than ages 50 and 55. So I think it would be interesting to see whether… the same results would be found if they looked at a younger population of patients, a population of patients who are more likely to get autoimmune disease,” she said.