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Journal Club
VITAL: Vitamin D, Omega-3 and Autoimmune Disease Prevention
An ancillary study of the VITAL trial found that vitamin D supplementation reduced incident autoimmune disease in older adults, raising the question of whether simple supplements can prevent autoimmunity.
Recording
The discussion
Background. Observational data have long linked low vitamin D and low omega-3 fatty acid intake with autoimmune disease, but such associations are vulnerable to confounding. VITAL offered a rare chance to test prevention in a large randomized trial.
What the study showed. VITAL randomized more than 25,000 US adults (men 50 and older, women 55 and older) in a two-by-two factorial design to vitamin D3 2000 IU daily and/or marine omega-3 fatty acids 1 g daily, or placebo, for a median of about five years. In the autoimmune ancillary study, vitamin D reduced confirmed incident autoimmune disease by roughly one fifth, with a stronger effect after the first two years. Omega-3 supplementation showed a smaller reduction that did not reach statistical significance for confirmed cases but did when probable cases were included. Rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease and psoriasis were the most common new diagnoses. Follow-up after the trial ended suggested the protective effect of vitamin D faded after stopping.
How it changes practice. For older adults, especially those with a family history of autoimmune disease or other risk factors, vitamin D supplementation is inexpensive, safe at this dose and now supported by randomized evidence. It is reasonable to discuss with patients, while being clear that the absolute risk reduction is modest and that it is not a treatment for established disease.
Open questions. The trial enrolled older adults, so we do not know whether results apply to younger people, when most autoimmune diseases begin. Baseline vitamin D levels were mostly adequate, and benefit in deficient people may differ. Individual disease endpoints were too few to analyze reliably, and whether the effect requires continuous supplementation needs further study.
Key takeaways
• Vitamin D3 2000 IU daily reduced confirmed autoimmune disease by roughly one fifth in older adults.
• Benefit appeared stronger after two years and seemed to fade after stopping.
• Omega-3 results were suggestive but less certain.
• The absolute benefit is modest, and the findings concern prevention, not treatment.
Questions for peers
1. Would you recommend vitamin D to first-degree relatives of patients with RA or lupus based on VITAL?
2. How should we discuss supplements with patients who expect them to treat established autoimmune disease?
3. What trial design would best test autoimmune prevention in younger, higher-risk populations?
References
1. VITAL autoimmune disease ancillary study: Hahn J et al. BMJ 2022. Vitamin D supplementation for about 5 years reduced confirmed incident autoimmune disease. PubMed
2. VITAL main trial: Manson JE et al. N Engl J Med 2019. Vitamin D did not reduce invasive cancer or major cardiovascular events; design of the parent trial. PubMed
3. VITAL post-trial autoimmune follow-up: Costenbader KH et al. Arthritis Rheumatol 2024. Suggested the protective effect of vitamin D on autoimmune disease waned after supplementation stopped. PubMed
At a glance
Format
Journal Club
Reviewed by Farhan Tahir, MD, FACR
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