• A large clinical trial has shown that vitamin D and fatty acid supplements are linked to lower rates of autoimmune diseases such as psoriasis and rheumatoid arthritis.
• Among the more than 25,000 older adults who participated in the study, those who took vitamin D and/or omega-3 supplements had a significantly lower incidence rate of autoimmune conditions.
• Future research will explore the longer-term impact of these types of supplements on autoimmune conditions.

Vitamin D and omega-3 (fish oil) supplements may help lower the risk of autoimmune disease such as psoriasis by as much as 30 percent, according to a new study from researchers at Harvard University and Brigham and Womens’ Hospital in Boston. The research was presented on Nov. 7 at the 2021 annual meeting of the American College of Rheumatology.

“[The] trial proved a couple of things,” said Dr. Karen Costenbader, lead author of the study. “One is that these doses (2,000 IU of vitamin D a day and one gram of fish oil a day) were very safe for older, community-living people (men age 50 and above and women age 55 and above). The second is that they actually reduced the overall incidence of new autoimmune disease, including psoriasis, by 25 percent to 35 percent.”

In past studies, researchers determined that low levels of vitamin D or omega-3 could put people at higher risk for developing autoimmune disease — conditions in which the immune system attacks the body’s healthy tissues. These conditions include psoriasis, rheumatoid arthritis, polymyalgia rheumatica, and autoimmune thyroid disease. However, less is known about whether taking supplements decreases a person’s likelihood of developing these conditions.

“People are always interested in which supplements and vitamins they should take, and for many of the new fad supplements, there is very little data and there might even be harms,” Dr. Costenbader told MyPsoriasisTeam.

To learn more, researchers conducted the vitamin D and omega-3 trial, dubbed VITAL. They enrolled more than 25,000 American adults over the age of 50. Each person was assigned to take vitamin D, omega-3, both, or a placebo (sugar pill).

The clinical trial was double blind, which means that both the participants and their doctors did not know whether the participant was receiving a placebo or a true supplement. Double-blind, placebo-controlled trials are the most reliable way to determine whether a particular treatment is effective.

The researchers followed the study participants for more than five years. They found that people who took vitamin D or omega-3 supplements had a lower risk of autoimmune disease, compared to those who took the placebo.

“For psoriasis prevention, there was a bigger effect of vitamin D than of fish oil,” Dr. Costenbader said. “Both have known anti-inflammatory and beneficial immune-modulating effects. A longer-term extension study is ongoing to see how long the benefits last.”

In the meantime, she said that older adults who may be at risk of developing an autoimmune condition — such as those with a family history — may benefit from taking vitamin D and omega-3 supplements daily. According to the National Psoriasis Foundation, people should speak with their health care provider before taking new supplements.

Learn more about vitamins and supplements for psoriasis.