Study: Vitamin D Supplements May Help Prevent Autoimmune Disease

vitamin d supplement

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Key Takeaways

  • A new study found that 2,000 IU of vitamin D per day, taken with or without omega-3s, may help prevent autoimmune disease.
  • Currently, there are no known interventions to cure or prevent autoimmune diseases.
  • Since the study only included adults age 50 and over, additional research is needed to confirm if the results are applicable to the general population.

During the winter, people often turn to vitamin D supplements to improve their mood and fatigue. Vitamin D deficiency has also been linked to depression, bone softening, and even severe COVID.

A new study found that vitamin D supplements may offer an additional benefit. They were shown to reduce the risk of autoimmune disease by 22% over a five-year period for people age 50 and older.

“There really isn’t any known way to prevent autoimmune disease. There are no medications or treatments that have been approved for the primary prevention of autoimmune disease in the general population,” JoAnn E. Manson, MD, DrPH, a professor of medicine at Harvard Medical School and co-author of the study, told Verywell. “This would be the first time an approach has been suggested and found to be of benefit.”

More than 24 million Americans currently live with autoimmune diseases. Autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and lupus, develop when the body’s immune system fights its own cells.

Scientists are still learning exactly what causes autoimmune diseases, which makes it difficult to create preventive treatment plans. Many believe that both genetics and environmental factors may contribute to the development of autoimmune diseases.

Experts also suggest that autoimmune disease rates are rising in many parts of the world. A 2016 report in the American Journal of Epidemiology pointed out that there are still no cures for any of the 80 different autoimmune diseases despite improving treatment options.

Since autoimmune diseases can develop slowly, they can be hard to diagnose. If left untreated, these diseases can have irreversible or even life-threatening effects.

Since there are no known cures, researchers like Manson and her colleagues were motivated to find ways to reduce the risk of developing autoimmune diseases in the first place.

What the Researchers Found

Manson directed the VITAL Trial, a five-year randomized double-blind clinical trial of more than 25,000 participants aged 50 and above. VITAL researchers are studying connections between vitamin D and omega-3 supplements and the risk of cancer, heart disease, and stroke.

“We and our colleagues were interested in looking at whether vitamin D and omega-3s could also prevent autoimmune diseases because these supplements are known to reduce inflammation and to have benefits for the immune system,” Manson said.

The study found that 2,000 IU per day of vitamin D supplement, with or without omega-3s, was associated with a lower risk of autoimmune disease compared to placebo.

In addition to vitamin D, researchers examined the connection between omega-3s and autoimmune disease risk. They found that omega-3 supplements didn’t make a significant difference when they were taken without vitamin D.

However, the study suggested that there may be additional benefits after taking the omega-3 supplements for a longer period of time.

“I must say I was as surprised as anyone because, despite all the very strong immunologic and anti-inflammatory mechanisms, actually seeing that giving a supplement reduces the risk of developing disease is quite astonishing,” Karen H. Costenbader, MD, MPH, a professor of medicine at Harvard Medical School and senior author of the study, told Verywell.

What About Dietary Sources of Vitamin D?

While this study found promising results, additional research is needed to show if the results are generalizable.

“There are still many questions to be answered and further studies to be done,” Costenbader said, adding that her team plans to continue following up with the participants to see how the results change over time.

Since the VITAL Trial only included participants aged 50 and older, the researchers want to conduct future studies with different age groups.

“I would also really like to study this question in younger adults who may have a higher genetic risk of developing autoimmune disease and to test whether the supplements have a similar beneficial preventive effect,” Costenbader said.

For this study, the researchers only tested one dose of each supplement (2,000 IU per day of vitamin D and 1 gram per day of omega-3s). Costenbader said it would be beneficial for future studies to test different doses to determine if there’s an “optimal dose for autoimmune disease prevention.”

Manson added that the study findings will need to be replicated before general recommendations can be made. While there may be similar benefits from dietary sources of vitamin D and omega-3, it would require a complex study to show proven results.

Plus, reaching 2,000 IU per day of vitamin D from dietary sources would be challenging. A serving of sockeye salmon, for example, has 570 IU and a glass of fortified 2% milk only contains 120 IU.

Despite the limitations, these findings are encouraging, especially for individuals who may be considered at high risk for developing autoimmune diseases due to genetic or environmental factors.

“We found over the 5.3 years of treatment with vitamin D at 2,000 IU/day and the omega-3s at 1 g a day, that the supplements were safe, well-tolerated, and did not have adverse effects,” Manson said. “They’re inexpensive and highly accessible. Given there are no other known methods for preventing autoimmune disease, this is an exciting strategy that needs further study.”

What This Means For You

Talk to your healthcare provider before taking any new supplements. Together, you can decide if taking these supplements is right for you. The FDA does not regulate supplements. Look for a USP Verification Mark on the supplement to verify that that it does contain the ingredients listed on the label.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. National Institute of Environmental Health Sciences. Autoimmune diseases.

  3. National Institute of Allergy and Infectious Diseases. Autoimmune diseases.

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  5. Rose NR. Prediction and prevention of autoimmune disease in the 21st century: a review and previewAm J Epidemiol. 2016;183(5):403-406. doi:10.1093/aje/kwv292

  6. Manson JE, Cook NR, Lee IM, et al. Vitamin D supplements and prevention of cancer and cardiovascular diseaseN Engl J Med. 2019;380(1):33-44. doi:10.1056/NEJMoa1809944

  7. National Institutes of Health Office of Dietary Supplements. Vitamin D: fact sheet for health professionals.