Disclosures: The authors report receiving support from the NIH.
February 01, 2022
2 min read

Vitamin D, omega-3 fatty acids may reduce risk for autoimmune disease

Disclosures: The authors report receiving support from the NIH.
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Older adults who took vitamin D with or without omega-3 fatty acid supplementation had a significantly lower rate of autoimmune disease over 5 years compared with those who took placebo, according to findings published in The BMJ.

“This is the first direct evidence we have that daily supplementation may reduce [autoimmune disease] incidence, and what looks like more pronounced effect after 2 years of supplementation for vitamin D,” Karen Costenbader, MD, MPH, director of the lupus program at Brigham and Women’s Hospital and a professor at Harvard Medical School, said in a press release.

Reductions in incidence of autoimmune diseases with supplementation
Hahn J, et al. BMJ. 2022;doi:10.1136/bmj-2021-066452.

Costenbader and colleagues conducted a two-by-two factorial designed, nationwide, randomized, double-blind, placebo-controlled study of 12,786 men aged 50 years or older and 13,085 women aged 55 years or older in the U.S. Participants were randomly assigned to receive one of four treatment groups: vitamin D (2,000 IU/day) with omega-3 fatty acid (1,000 mg/day) supplementation, vitamin D with a placebo, omega-3 fatty acid with a placebo or placebo only. The researchers reviewed medical records to assess the incidence of autoimmune diseases from baseline to a median follow up of 5.3 years.

Among the participants, 71.3% were non-Hispanic white and 20.2% were Black. The mean age was 67.1 years. The trial did not intentionally seek a population that was vitamin D deficient, Costenbader and colleagues noted.

Karen Constenbader

Overall, 123 participants in the vitamin D cohort and 155 participants in the corresponding placebo cohort developed a confirmed autoimmune disease during the study period (HR = 0.78; 95% CI 0.61-0.99). This amounted to a 22% reduction in incidence of autoimmune disease, according to the researchers.

Meanwhile, 130 participants in the omega-3 fatty acid cohort and 148 participants in the corresponding placebo cohort developed a confirmed autoimmune disease (HR = 0.85; 95% CI, 0.67-1.08), the researchers reported. This amounted to a 15% reduction in disease incidence; however, the reduction was not statistically significant, according to the researchers. When including probable cases of autoimmune disease, omega-3 fatty acids were associated with an 18% reduction in incidence.

Among the 6,468 participants who were randomly assigned to receive both vitamin D and omega-3 fatty acids, 63 developed an autoimmune disease (HR = 0.69; 95% CI, 0.49-0.96) compared with 88 participants who received placebo. Meanwhile, 60 participants who received only vitamin D (HR = 0.68; 95% CI, 0.48-0.94), and 67 who received only omega-3 fatty acids (HR = 0.74; 95% CI, 0.54-1.03) had confirmed autoimmune disease.
Compared with the placebo group, “the cumulative incidence of confirmed autoimmune disease over the 5 years of the trial was lower in all three of the groups receiving supplementation,” the researchers wrote.

Overall, both vitamin D and omega-3 fatty acids “were very effective at reducing the risk of new autoimmune diseases compared with people who only received placebo,” Costenbader told Healio. The findings are of “high” clinical importance since the supplements were well-tolerated and nontoxic, the researchers wrote.

“Now, when my patients, colleagues or friends ask me they take to reduce risk of autoimmune disease, I have new evidence-based recommendations for women aged 55 years and older and men 50 years and older,” Costenbader said in the release. “I suggest vitamin D 2,000 IU a day and marine omega-3 fatty acids (fish oil), 1,000 mg a day.”

However, she encouraged providers to talk to patients about potential contraindications before starting supplementation. For example, people with seafood allergies may not be able to take an omega-3 fatty acid supplement, Costenbader said.


Vitamin D supplements lower risk of autoimmune disease, researchers say. https://news.harvard.edu/gazette/story/2022/01/vitamin-d-reduced-rate-of-autoimmune-diseases-by-22/. Published Jan. 26, 2022. Accessed Jan. 28, 2022.

Hahn J, et al. BMJ. 2022;doi:10.1136/bmj-2021-066452.