Recently, researchers have studied the link between vitamin D and fish oil supplementation and the onset of autoimmune diseases. They found an association between taking both supplements, but especially vitamin D, for 5 years and a decrease in the rate of autoimmune disease.

Autoimmune disorders are chronic conditions in which the body faces health problems with a spontaneous inflammatory immune response, even in the absence of infection.

Here are some examples of autoimmune disorders:

  • – autoimmune thyroid disease
  • – type 1 diabetes
  • – inflammatory bowel disease
  • – multiple sclerosis
  • – psoriasis
  • – rheumatoid arthritis (RA)

Autoimmune diseases are the third most common in the industrialized world, and the leading cause of death worldwide in women.

As there is currently no cure and a person can only manage the symptoms, these diseases have major societal implications. Additionally, people with autoimmune diseases often miss long periods of employment. In addition to seeing their productivity affected, they have to face thousands of dollars in medical expenses that they can no longer afford.

Some studies have found that vitamin D and omega-3 fish oil may be able to regulate genes involved in inflammation and innate immune responses. Although animal trials have shown that vitamin D inhibits immune responses, disease development or progression, small trials of vitamin D supplementation in people with autoimmune diseases have shown negative results.

Meanwhile, a Danish study found that the risk of RA decreased by 49% for every 30 grams (g) increase in daily fatty fish consumption. Clinical trials are needed to determine if vitamin D or omega-3 supplements actually benefit people with autoimmune diseases.

But in a recent study, researchers from Boston (USA) examined the link between vitamin D and omega-3 fatty acid supplements and the onset of autoimmune disease in the context of a national placebo-controlled trial. They found that vitamin D supplementation reduced the risk of developing an autoimmune disease by 22%.

Additionally, omega-3 fatty acid supplementation reduced the risk of autoimmune disease by 15%, although these results were not statistically significant. Autoimmune diseases are a group of over 80 different diseases, and their prevalence and impact on health increases with age. This study is the first direct evidence that something can be done to prevent them in the elderly.

Furthermore, the clinical significance of these results is high because the supplements are non-toxic and well tolerated, and other effective treatments to reduce the incidence of autoimmune diseases are lacking.

The study is published in the journal BMJ

Clinical Trial: Vitamin D and Omega 3

The researchers recruited 25,871 participants across the United States in their Vitamin D and Omega-3 (VITAL) trial. At the start of the trial, 51% of participants were women aged 55 or older, while the rest were men aged 50 or older. None of the participants had a history of conditions such as cancer, cardiovascular disease or kidney failure, and all were instructed to limit their intake of vitamin D from outside sources to no more than 800 units. (IU) per day and not to take fish oil supplements.

After enrollment, the researchers randomly assigned the participants to two treatment groups. Participants received either 2,000 IU of vitamin D and a 1 g fish oil capsule or placebos daily. Placebos contained soybean oil or olive oil.

The researchers took blood samples from the participants at the start and during the study to determine their vitamin D and omega-3 fatty acid levels. Participants also completed questionnaires at the start of the study to identify lifestyle factors, such as use of vitamin D supplements and consumption of fish and dairy products.

They then completed questionnaires annually to provide information on:

  • – new disease diagnoses
  • – subscription to the supplement
  • – potential side effects of supplement or placebo treatments
  • – risk factors for cancer and cardiovascular disease.

The researchers followed the participants for 5 years.

At the end of the study period, they found that 93.1% of participants had completed the questionnaires and 81% had taken at least two-thirds of their supplements. Blood tests showed that after one year, 25-hydroxyvitamin D levels increased by 40% from baseline in people taking vitamin D. In contrast, in the placebo group, the changes were minimal.

The study authors also found that people taking omega-3 supplements had 54.7% more omega-3s in their blood, while individuals in the placebo group had only 2%. moreover. Participants in the vitamin D supplementation group, whether they also took fish oil or not, were 22% less likely to develop an autoimmune disease than those in the placebo group.

At the same time, participants in the “fish oil supplementation” group, whether or not they took vitamin D supplements, were 15% less likely to suffer from an autoimmune disease than those in the “placebo” group. After controlling for other factors, the researchers found that this relationship was not significant. They add, however, that if probable cases of autoimmune conditions were included, then omega-3 fatty acid supplementation reduced their risk by 18%.

Additionally, researchers observe that longer adherence to supplements led to greater benefits. Over the last three years of the trial, they found that vitamin D supplements reduced the number of confirmed autoimmune diseases by 39% compared to the placebo group. They also note a link between fish oil supplements and a 10% lower probability.

Overall, the researchers found a link between vitamin D and omega-3 fatty acid supplementation and a 30% lower risk of developing autoimmune disease, compared to a placebo.

Multiple mechanisms with Vitamin D and Omega-3

Vitamin D enters the nucleus and binds to the vitamin D receptor, regulating a wide range of vitamin D-responsive genes, many of which are involved in innate and adaptive immune system function. There are many well-known immunomodulatory actions of vitamin D, including potentially beneficial effects on B and T lymphocytes, macrophages, monocytes, dendritic cells, etc.

Similarly, for marine omega-3 fatty acids (fish oils), there are many well-known anti-inflammatory and “pro-resolving” mechanisms, including the downregulation of inflammatory mediators, such as prostaglandins and leukotrienes, and the upregulation of specialized pro-resolving mediators, which act to ‘clean up’ after inflammation and which could certainly be responsible for reducing the onset of new autoimmune diseases,” he said. she adds.

The researchers conclude that taking vitamin D and fish oil supplements over time can reduce the incidence of autoimmune diseases.

They also note that their research has some limitations. Because they primarily assessed older adults, they say their results may not be generalizable to younger people.


Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial

Does vitamin D affect risk of developing autoimmune disease?: a systematic review

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