Autoimmune Diseases and Omega-3: Does the Effect Last Longer than Vitamin D?
Omega-3s are possible allies also against autoimmune diseases. Their beneficial effects seem to last even longer than those of another important immune system regulator: vitamin D. But how to take them for effective prevention?
Both vitamin D supplements and Omega-3 supplements can help reduce the risk of developing autoimmune diseases, but when stopped, the protective effect of vitamin D tends to fade, while that of Omega-3 lasts longer. This is revealed by an analysis of data collected during the VITAL study, published in Arthritis & Rheumatology, the official journal of the American College of Rheumatology, by a group of researchers led by JoAnn E. Manson, an expert from Harvard University (Boston, USA).
Started to evaluate the protective effects of Vitamin D and Omega-3 against cardiovascular diseases and cancers, the study revealed the usefulness of these nutrients also against autoimmune diseases. Now, Manson and collaborators explain, it is possible to say that two years after stopping supplementation «the protective effect of 2,000 IU per day of vitamin D has vanished, while 1,000 mg per day of Omega-3 fatty acids continue to reduce the incidence of autoimmune diseases».
Omega-3 and autoimmune diseases
Omega-3 fats influence the activity of cells of the immune system. In particular, they are known for their tendentially anti-inflammatory properties, which make them possible allies against diseases characterized by increased inflammation – like most autoimmune diseases.
The hypothesis that these nutrients may be useful in the treatment of these diseases has already been tested in the past. The collected data suggest effectiveness against symptoms of rheumatoid arthritis, systemic lupus erythematosus, and psoriasis. Evidence of the usefulness of Omega-3s in preventing these diseases is instead scarcer.
The VITAL study
The VITAL study involved nearly 26,000 men and women aged 50 and 55 or older, respectively, who had to take vitamin D (2,000 IU daily), Omega-3 (1 gram daily), both or a placebo. In particular, those who took Omega-3 received 460 mg per day of EPA (eicosapentaenoic acid) and 380 mg per day of DHA (docosahexaenoic acid), the two marine Omega-3s, as well as those biologically active.
Throughout the study (which involved each participant for an average of 5.3 years) all new cases (confirmed or suspected) of autoimmune diseases were recorded. Data published in 2022 in the British Medical Journal revealed that vitamin D (with or without Omega-3) reduced the incidence of autoimmune diseases by 22%. In the case of Omega-3 supplements (taken with or without vitamin D) a reduction in the incidence of confirmed cases of 15% was observed, which however was not statistically significant; the results changed including possible cases as well: in this way, the reduction in incidence following Omega-3 supplementation was significant and equal to 18%.
In the new study published in Arthritis & Rheumatology, Manson and collaborators obtained new information from over 21,000 of the original VITAL study participants. In particular, they analyzed new (confirmed or suspected) cases of rheumatoid arthritis, polymyalgia rheumatica, psoriasis, autoimmune thyroiditis, inflammatory bowel diseases, and any other autoimmune disease that emerged in the two years following the suspension of supplementation.
There were 255 new cases among those who took vitamin D and 234 among those who took Omega-3. Compared to new cases among participants who took a placebo, these numbers indicate that the effect of vitamin D fades quickly after stopping intake, while that of marine Omega-3s persists and remains significant.
Autoimmune diseases: vitamin D or Omega-3?
These new results suggest that to reduce the risk of developing an autoimmune disease vitamin D supplements must be taken continuously. Omega-3 supplements, instead, seem to have a longer-term effect (at least up to 2 years after stopping intake). Moreover, the available data suggest that Omega-3s may have a greater protective effect against rheumatoid arthritis and inflammatory bowel diseases.
New research will help to understand the protective effects of these “good” fats even at younger ages and when used at different dosages from those tested in the original VITAL study. It is also not to be excluded that the benefits of supplements may increase when also controlling other factors that can impact autoimmune phenomena, such as diet, lifestyle, and stress.
Bibliographic references:
Costenbader KH et al. Vitamin D and Marine n-3 Fatty Acids for Autoimmune Disease Prevention: Outcomes Two Years After Completion of a Double-Blind, Placebo-Controlled Trial. Arthritis Rheumatol. 2024 Jan 25. doi: 10.1002/art.42811
Hahn J et al. Vitamin D and marine Omega-3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial. BMJ. 2022 Jan 26;376:e066452. doi: 10.1136/bmj-2021-066452
