Vitamin D3 and omega-3 fatty acid supplementation reduce the risk of developing autoimmune disease by 25% to 30% in older adults, according to study results presented at the American College of Rheumatology (ACR) Convergence 2021.

Because of the lack of clinical data, study authors conducted a nationwide, randomized, double-blinded, placebo-controlled study (Vitamin D and Omega 3 Trial; VITAL) to determine the effect of vitamin D and omega-3 supplementation on the risk of developing autoimmune disease.

From November 2011 to March 2014, study participants (men aged ≥50 years and women aged ≥55 years) were randomly assigned to receive vitamin D3 (2000 IU/d) and/or omega-3 fatty acids (1000 mg/d) or placebo. The treatment was continued through December 2017. Incident autoimmune diseases were confirmed by physicians and reported by participants annually.

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The primary outcome measure was the total incident autoimmune diseases, including rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease, and psoriasis. Researchers also determined the individual most common and probable autoimmune disease incidence, which served as secondary outcome measures.

The study cohort included 25,871 participants, among whom 71% self-reported to be non-Hispanic White, 20% Black, and 9% other racial/ethnic groups; 51% were women, and the mean age was 67.1 years. The median follow-up time was 5.3 years.

Incident autoimmune disease was reported among 117 participants in the vitamin D3 group and 150 participants in the placebo group (hazard ratio [HR], 0.78; 95% CI, 0.61-1.00; P =.04); confirmed autoimmune disease was also diagnosed in 123 participants in the omega-3 group and 144 participants in the placebo group (HR, 0.85; 95% CI, 0.67-1.09). Excluding the first 2 years, the HRs for the primary outcome were 0.61 (0.43-0.86; n=137) and 0.90 (0.64-1.26) in the vitamin D3 and omega-3 groups, respectively.

In the subgroup analysis, the HRs for all 3 active arms vs placebo/placebo were reduced by 25% to 30%. The HR required to prevent autoimmune diseases by using the 2 supplements for 5 years was 167 (94-769). 

Researchers concluded, “Supplementation for 5 years with vitamin D3 and/or [omega]-3 fatty acids reduced incident autoimmune disease by [25%]-30% in older adults vs those who received neither supplement. The effect of vitamin D3 appeared stronger after 2 years of supplementation.”

Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a complete list of affiliations.


Hahn J, Cook N, Alexander E, Friedman S, Bubes V, Walter J, Kotler G, Lee I, Manson J, Costenbader K. Vitamin D and marine n-3 fatty acid supplementation and prevention of autoimmune disease in the VITAL randomized controlled trial. Presented at: ACR Convergence 2021; November 3-10, 2021. Abstract 0957.

This article originally appeared on Rheumatology Advisor