by Siwar Ala (VitalremedyMD Inc.)
This new clinical study has found that long term supplementation with Vitamin D3, Omega-3 fatty acids, or both of them could reduce the risk of developing an autoimmune disease.
Previous research has showed vitamin D3 is associated with reduced risk of several autoimmune diseases, while dietary marine-derived long-chain omega-3 (n−3) fatty acids decrease the inflammation and ameliorate symptoms in some autoimmune diseases.
In a recent U.S. nationwide randomized, double-blind, placebo-controlled trial of 25,871 participants of which men ≥ 50 years and women≥ 55 years, the researchers divided the participants into four randomly assigned groups, each of which received a daily allotment during 5 years of either:
- An omega-3 placebo and a vitamin D3 placebo
- 1000 milligram (mg) of an omega-3 fatty acid supplement and 2,000 international units (IU) of vitamin D3
- An omega-3 placebo and 2,000 IU of vitamin D3
- 1000 mg of an omega-3 fatty acid supplement and a vitamin D3 placebo 
Supplementation for 5 years with vitamin D3 and/or n-3 fatty acids reduced the incident of autoimmune disease by 25-30% in older adults vs those placebo groups. It was also found that the protective effect of vitamin D3 appeared to be stronger after 2 years of supplementation. 
1- Hahn J, Cook N, Alexander E, Friedman S, Bubes V, Walter J, Kotler G, Lee I, Manson J, Costenbader K. Vitamin D3 and Marine n-3 Fatty Acid Supplementation and Prevention of Autoimmune Disease in the VITAL Randomized Controlled Trial [abstract]. Arthritis Rheumatol. 2021; 73 (suppl 10). https://acrabstracts.org/abstract/vitamin-d-and-marine-n-3-fatty-acid-supplementation-and-prevention-of-autoimmune-disease-in-the-vital-randomized-controlled-trial/. Accessed November 21, 2021.