Vit D supplements reduce autoimmune disease risk by 22%: VITAL trial

Vitamin D supplementation for five years, with or without omega 3 fatty acids, reduced autoimmune disease by 22%. Omega 3 fatty acid supplementation with or without vitamin D reduced the autoimmune disease rate by 15% which was not statistically significant. These findings have been reported in the January 2022 BMJ research.

Autoimmune diseases, characterized by an inflammatory autoimmune response to self-tissues, are the third leading cause of morbidity in the industrialized world and a leading cause of mortality among women.

Vitamin D and marine-derived, long-chain omega 3 fatty acids are two nutritional supplements investigated as potential autoimmune disease treatments.

The lipid-soluble active form of vitamin D (1,25-hydroxyvitamin D) regulates genes involved in inflammation and acquired and innate immune responses.

Animal models of autoimmune disease have reported vitamin D to be beneficial because it inhibits the development or progression of the disease, but observational studies have found conflicting results, and small trials of vitamin D supplementation in people with established autoimmune disease have mainly reported disappointing results.

Randomized controlled trials of people with prevalent rheumatoid arthritis, systemic lupus erythematosus, and psoriasis have also shown improvements in outcomes with omega 3 fatty acids, but few studies have examined omega 3 fatty acids in autoimmune disease prevention.

In the VITAL trial, the researchers from the Chan School of Public Health tried to investigate whether vitamin D and marine-derived long-chain omega 3 fatty acids reduce autoimmune disease risk.

25 871 participants, consisting of 12 786 men ≥50 years and 13 085 women ≥55 years at enrollment, were included in the trial.

Vitamin D (2000 IU/day) or matched placebo, and omega 3 fatty acids (1000 mg/day) or matched placebo was administered.

Participants self-reported all incident autoimmune diseases from baseline to a median of 5.3 years of follow-up; these diseases were confirmed by an extensive medical record review.

Cox proportional hazard models were used to test the effects of vitamin D and omega 3 fatty acids on autoimmune disease incidence.

The primary endpoint was all incident autoimmune diseases confirmed by medical record review: rheumatoid arthritis, polymyalgia rheumatica, autoimmune thyroid disease, psoriasis, and all others.

25 871 participants with a mean age of 67.1 years were enrolled and followed for a median of 5.3 years.

18 046 self-identified as non-Hispanic white, 5106 as black, and 2152 as other racial and ethnic groups.

For the vitamin D arm, 123 participants in the treatment group and 155 in the placebo group had a confirmed autoimmune disease.

In the omega 3 fatty acids arm, 130 participants in the treatment group and 148 in the placebo group had a confirmed autoimmune disease.

Compared with the reference arm (vitamin D placebo and omega 3 fatty acid placebo; 88 with confirmed autoimmune disease), 63 participants who received vitamin D and omega 3 fatty acids, 60 who received only vitamin D, and 67 received only omega 3 fatty acids had confirmed autoimmune disease.

"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. We are continuing to follow participants for two years in an extension study to test the time course of this autoimmune disease reduction effect. Further trials could test these interventions in younger populations, and those with high autoimmune disease risk," the authors noted.

Reference:

Hahn J., Cook N.R., Alexander E.K., et. al, Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial, BMJ 2022; 376 doi: https://doi.org/10.1136/bmj-2021-066452 (Published 26 January 2022)