Autoimmune diseases and Omega-3: does the effect last longer than vitamin D?
Omega-3s are also possible allies against autoimmune diseases. Their beneficial effects seem to last even longer than those of another important regulator of the immune system: vitamin D. But how to take them for effective prevention?
Both vitamin D and Omega-3 supplements can help reduce the risk of developing autoimmune diseases, but when you stop taking them the protective effect of vitamin D tends to fade, while that of Omega-3 lasts longer. Revealing this is an analysis of data collected during the VITAL study, published in the pages of Arthritis & Rheumatology, the official journal of theAmerican College of Rheumatology, by a group of researchers coordinated by JoAnn E. Manson, an expert at Harvard University (Boston, USA).
Initiated to evaluate the protective effects of Vitamin D and Omega-3 against cardiovascular disease and cancer, the study had revealed the usefulness of these nutrients against autoimmune-based diseases as well. Now, Manson and coworkers explain, it is possible to say that two years after discontinuing supplementation "the protective effect of 2,000 IU per day of vitamin D has waned, 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 immune system cells. In particular, they are known for their tendentially anti-inflammatory properties, making them possible allies against diseases characterized by increased inflammation-such as most autoimmune diseases.
The hypothesis that these nutrients may be useful in the treatment of these diseases has been tested before. Collected data suggest efficacy against the symptoms of rheumatoid arthritis, systemic lupus erythematosus, and psoriasis. Evidence for the usefulness of Omega-3s in preventing these diseases, however, is more scant.
The VITAL study
The VITAL study involved nearly 26 thousand men and women aged 50 and 55 years and older, respectively, who had to take vitamin D (2,000 IU per day), Omega-3 (1 gram per day), both or a placebo. Specifically, 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-derived Omega-3s and the biologically active ones.
Throughout the study (which involved each participant for an average of 5.3 years) all new cases (definite or presumed) of autoimmune diseases were recorded. Data published in the British Medical Journal in 2022 revealed that vitamin D (with or without Omega-3) had reduced the incidence of autoimmune diseases by 22 percent. In the case of Omega-3 supplements (taken with or without vitamin D), a reduction in the incidence of definite cases of 15% had been observed, but this was not found to be statistically significant; the results changed by including possible cases as well: thus, the reduction in incidence following Omega-3 intake was significant and 18%.
In the new study published in Arthritis & Rheumatology, Manson and collaborators were able to obtain new information from more than 21 thousand of the participants in the original VITAL study. Specifically, they analyzed the new cases (certain or suspected) of rheumatoid arthritis, polymyalgia rheumatica, psoriasis, autoimmune thyroiditis, inflammatory bowel disease, and any other autoimmune diseases that emerged in the two years after stopping taking supplements.
This resulted in 255 new cases among those who had taken vitamin D and 234 among those who had taken Omega-3. Compared with new cases among participants who had taken a placebo, these numbers indicate that the effect of vitamin D fades rapidly after discontinuation of its intake, while that of marine-derived Omega-3 persists and remains significant.
Autoimmune diseases: better vitamin D or Omega-3?
These new findings suggest that to reduce the risk of developing an autoimmune disease, vitamin D supplements should be taken continuously. Omega-3 supplements, on the other hand, appear to have a longer-term effect (at least up to 2 years after discontinuation of intake). Not only that, the evidence suggests that Omega-3s may have a greater protective effect against rheumatoid arthritis and inflammatory bowel disease.
New research will help to understand the protective effects of these "good" fats even at younger ages and when used at different dosages than the only one tested in the VITAL study. It also cannot be ruled out that the benefits of supplements may increase when other factors that may have an impact on autoimmunity phenomena, such as dietary habits, lifestyle and stress, are also kept in check.
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
