In the news: In the news: VITAL Study: Vitamin D Lowers Autoimmune Disease Risk in Middle-Aged & Older

Can Autoimmune Disease Rates be Reduced?

Autoimmune diseases (AD) affect up to 23.5 million Americans according to the National Institutes of Health – and prevalence is rising. Autoimmune conditions are common in older adults and are a leading cause of morbidity as well as mortality among women, in economically developed countries. Effective treatments for AD are lacking, with treatments focused on managing symptoms and controlling immune responses. Thus, finding ways to lower the risk of developing AD is important.

A newly published study conducted by Harvard researchers offers the first direct evidence that daily supplementation with vitamin D or vitamin D and omega-3 fatty acids may lower the rate of AD in middle-aged and older adults(1).

The VITAL Trial: Background

The current investigation was a pre-planned ancillary study of the large-scale vitamin D and omega-3 trial (VITAL). VITAL is a randomized placebo-controlled trial of 25,871 racially diverse men and women aged 50 and older (average age of 67 years.

VITAL Participants received either 2000 IU vitamin D with 1,000 mg omega-3 fatty acids; vitamin D with a placebo; omega-3 with a placebo; or two placebos daily, for a median 5.2 years. Vitamin D supplement-ation from outside sources was limited to 800 IU per day for participants, who also had to forego the use of supplemental fish oil.

Current Study

Participants self-reported all incident AD during the study period, which were confirmed by extensive medical record review. The primary endpoint was all incident AD (rheumatoid arthritis, psoriasis, polymyalgia rheumatica, autoimmune thyroid disease, inflammatory bowel disease and all others).

The Harvard team chose to study the effects of vitamin D on AD because the vitamin regulates a wide array of genes involved in inflammation and immunity. Vitamin D has also been associated, though inconsistently, with reduced risk of several AD (particularly multiple sclerosis) in observational studies. Marine omega-3s have been shown to reduce systemic inflammation and improve symptoms in some AD.

Results

The research team found that vitamin D – with or without omega-3 fatty acids – reduced AD by 22% compared to placebo (p=0.05). That rate fell to 39% after at least two years of supplementation (p=0.005).

Omega-3 fats, with or without vitamin D, reduced disease rate by 15%, though this was not statistically significant. When participants with probable AD were included in the analysis, the rate was 18%.

In pre-specified secondary analyses, no specific AD was statistically significant (possibly because of the small number of participants with individual disease) although the hazard ratios favored supplementation for almost all diseases. Rheumatoid arthritis incidence was about 40% lower in the supplementation groups than in the placebo group.

Comments

The authors note that “the clinical importance of the trial is high because these are well tolerated, non-toxic supplements”. Additionally, they saw consistent results across autoimmune diseases and increasing effects with time. The researchers are, in fact, extending the study 2 years to see whether further risk reductions accrue.

The authors also point to the need for studies in younger people who experience AD earlier if life. Interestingly, the effects seen in the study were more pronounced in those with a family history of AD and in those with lower vs. higher BMI. It’s also worth noting that this was not a study in those with vitamin D deficiency – only 13% began the study with deficient vitamin D levels (<20 ng/mL).

References

1. Hahn J, et al. Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial. BMJ 376::e066452, 2022.