Cold Vitamin D and Fish Oil Help Preventing Autoimmune Diseases?

Autoimmune diseases are characterized by an inflammatory response to self-tissues and are the 3rd cause of morbidity in the industrialized world and a leading cause of mortality among women. They are chronic conditions that continue to increase their prevalence with age and are major societal and economic burdens due to the lack of effective treatments. 

The type of treatments that are currently available for these conditions aims to decrease the inflammatory response and modulate the immune system by using immunosuppressors and other medications that come with a wide variety of secondary adverse effects. 

The use of vitamin D and omega-3 fatty acids has been investigated as supplements for the treatment of autoimmune diseases. In vitro, vitamin D regulates genes involved in inflammation and acquired and innate immune responses. 

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.

One Danish observational study found a 49% reduction in rheumatoid arthritis risk for each 30 g increase in daily fatty fish intake (≥8 g fat/100 g fish).

Recently, a group of researchers from Boston found an association between taking both supplements, especially vitamin D for 5 years and a decreased rate of autoimmune disease. The study was published in the British Medical Journal. 

Both Vitamin D and Omega-3 Decrease Risk of Autoimmune Diseases

The randomized controlled trial included a total of 25,871 individuals (12,786 men ≥50 years and 13 085 women ≥55 years at enrollment). 

None of the participants had a history of conditions such as cancer, cardiovascular disease, or renal failure, and all received instructions to limit their vitamin D use from outside sources to no more than 800 international units (IU) per day and to not take fish oil supplements.

The participants were randomized into 2 groups, one group that received the treatment with a daily dose of 2,000 IU of vitamin D and 1 g of fish oil, and another group that received a placebo. 

Blood samples from the participants were taken at baseline and over the course of the study to know their levels of vitamin D and omega-3 fatty acids. The participants also filled out questionnaires at baseline to evaluate lifestyle factors, such as vitamin D supplement use, and fish and dairy intake. 

After 1 year of supplementation, the levels of 25-hydroxyvitamin D increased by 40% from baseline in the treatment group, while the placebo group changes were minimal. They also found that those participants taking omega-3 supplements had a 54.7 increase in omega-3 in their blood, with just a 2% increase in the placebo group.

The researchers concluded that vitamin D supplementation for five years, with or without omega 3 fatty acids, reduced autoimmune disease by 22%, while omega-3 fatty acid supplementation with or without vitamin D reduced the rate by 15%. 

Overall, they found an association between supplementation of both supplements and a 30% decreased risk of developing an autoimmune condition when compared to placebo.

The study shows us how easy interventions, such as supplementation or ensuring that an individual maintains optimal levels of a vitamin, such as vitamin D, could have a tremendous impact on our health. 


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

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