The Effect of the Mediterranean Diet and Fish Oil Supplements on Rheumatoid Arthritis — What is the Evidence?
I get a lot of questions about the role of diet and certain supplement use in autoimmune disease. Here is an evidence based approach to diet, specifically the role of consuming a Mediterranean Diet (MD) and fish oil in Rheumatoid Arthritis (RA), which is an autoimmune disease affecting the joints.
Nearly a quarter of individuals with rheumatoid arthritis report that diet has had an effect on their RA symptoms. One survey study evaluating 300 patients asked about consumption of 20 specific foods and whether these foods made their RA symptoms better, worse or unchanged. Blueberries and spinach were the foods most often reported to improve RA symptoms, while soda with sugar and desserts were those most often reported to worsen RA symptoms. Younger age, increased sleep, warm room temperature, and the use of vitamin/mineral supplements were each associated with reporting that foods affect rheumatoid arthritis symptoms [1].
What is the objective evidence that certain foods may help rheumatoid arthritis symptoms, or perhaps may even prevent RA from occurring in a susceptible population? Unfortunately, it is difficult to do studies on diet and autoimmune disease, because there can be biases in reporting symptoms and difficulty in having a placebo comparison group. There has been quite a bit of variability in the outcomes of these studies. However, given the “low risk” option of incorporating a specific type of diet in some patients to appropriate medication therapy for the chance of a larger upside (less joint pain, feeling better!), it is important to look at the evidence. One consistent type of diet that has been looked at is the Mediterranean Diet. Another is the use of fish oil, in the form of supplements.
Mediterranean Diet
The Mediterranean Diet (MD) is characterized by an abundance of plant based foods such as unrefined cereals, fruits, vegetables, legumes and extra virgin olive oil (EVOO), a moderate consumption of poultry, dairy products and eggs and a low consumption of sweets and red meat. This diet is high in anti-oxidants and anti-inflammatory nutrients and may have the potential to modulate inflammatory pathways in RA. However, the evidence is limited and has been studied in 2 clinical trials. One study examined 130 women with RA in Glasgow, Scotland. One group attended a 6 week cookery course on MD and continued this diet; and the other ate their usual diet. At 6 months, the intervention group MD patients had a significant benefit in overall report of feeling well, pain scores and early morning stiffness (EMS). However, other measures of RA activity such as tender and swollen joints, and inflammatory markers in the blood such as erythrocyte sedimentation rate (ESR) and C-reactive Protein (CRP) did not differ between groups [2, 3].
In the other study, 51 patients with RA were studied in Sweden. The rheumatoid arthritis patients were randomly allocated into the Mediterranean diet (MD) versus a “Western” Diet for 3 months.
The MD group showed improvements in RA outcomes such as patient reported pain scores, swollen and tender joint counts, vitality and mental health. Although the study showed that adjusting to the MD can result in a reduction in inflammatory activity and an increase in physical function, the findings may not be generalizable since it included mostly women, adjusted the MD to suit the Swedish subjects and had a short duration [2,4]. It will be important to analyze more studies on the Mediterranean diet in the future.
Fish Oil Supplements
n-3 polyunsaturated fatty acids (n-3 PUFA) such as the fish oils eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) are often low in Western diets, and as such patient’s often ask about taking them to help lower their “inflammation.” Dietary supplementation with these “omega-3” vitamins and other natural foods high in n-3 PUFAs such as flaxseed, chia seeds, canola and walnuts may have a number of anti-inflammatory actions such as a reduction in the production of inflammatory “cytokines.” Some cytokines are “pro-inflammatory” chemicals in the body that may initiate and propagate autoimmune diseases (where the body may lose its ability to discern its own cells and attacks itself). In an attempt to study the anti-inflammatory actions of n-3 PUFA in RA, there have been a range of clinical trials using n-3 PUFA oral supplements. The studies have shown that in the 1 gram doses of these supplements, there may be some potential effects of these fish oils in decreasing the need for non-steroidal anti-inflammatory drugs (NSAIDs- such as ibuprofen, naproxen), NSAID usage and a trend towards greater effects on the more subjective elements of disease such as joint stiffness and tenderness of joints, reported swelling of joints and fatigue. On the other hand, there was less evidence on more objective features of active RA such as on the laboratory markers of inflammation or progression of disease on x-rays or other imaging.
What about the relationship between a MD pattern and the risk of developing rheumatoid arthritis in the future? A recent study from France in a large prospective cohort of healthy French women showed that eating a Mediterranean diet did not reduce the incidence of rheumatoid arthritis; although if one was a smoker, eating a Mediterranean diet did have an effect on potentially reducing the incidence of RA [6].
What about for overall cardiovascular risk? Clinical studies in humans have been mixed in terms of supporting the protective benefits of fish oil supplementation.
The Vital Study:
A daily 1 gram Omega-3 supplement did not seem to protect most healthy people who are at low risk or average risk for heart disease against future heart problems. However, certain groups may have some benefit: those people who ate less than 1.5 servings of fish a week or those who did not eat fish at all. For these patients there was a 19% reduction major cardiovascular events with a 40% reduction in heart attacks. African American participants also benefited more, with a 77% reduction in heart attack for those receiving omega-3 fatty acids compared with those taking placebo.
The REDUCE-IT Trial:
This trial looked at the effect of high-dose fish oil supplements on people with high blood triglyceride levels who were at elevated cardiovascular risk. In contrast to previous studies, REDUCE-IT found a significant reduction in cardiovascular events among study subjects who took the high-dose fish oil supplements (4 grams of a fish oil called eicosapentanoic acid, or EPA) [7].
The Bottom Line on the Mediterranean Diet & Rheumatoid Arthritis
Speak to your doctor about any potential risks and medication interactions before taking any supplements. Getting your omega-3 fatty acids from food is usually preferable to supplements and having a healthy diet to replace less healthful foods such as red meat, processed foods or refined grains is always a good idea. Omega-3 fatty acids may help in reducing your need for NSAIDs and may potentially improve joint stiffness in RA and overall well being in the background of appropriate medical therapy as advised by your physician or rheumatologist.
Dr. Jain of Magnolia Rheumatology is a board-certified rheumatologist serving the Westchester County, Rockland County, and Greenwich, CT area. She has over 10 years of experience in treating patients with all aspects of rheumatic diseases, including rheumatoid arthritis. To learn more, call Magnolia Rheumatology to make an appointment via telehealth or at our office in Scarsdale, New York, Westchester County.
Sources:
Tedeschi SK, Frits M, Cui J, et al. Diet and Rheumatoid Arthritis Symptoms: Survey Results From a Rheumatoid Arthritis Registry. Arthritis Care Res (Hoboken). 2017;69(12):1920-1925. doi:10.1002/acr.23225
Petersson, S. , Philippou, E. , Rodomar, C., Nikiphorou, E. The Mediterranean diet, fish oil supplements and Rheumatoid arthritis outcomes: evidence from clinical trials. Autoimmunity Reviews, Volume 17, Issue 11,2018, Pages 1105-1114,
G. McKellar, E. Morrison, A. McEntegart, R. Hampson, A. Tierney, G. Mackle, et al. A pilot study of a Mediterranean-type diet intervention in female patients with rheumatoid arthritis living in areas of social deprivation in Glasgow. Ann Rheum Dis, 66 (2007), pp. 1239-1243
L. Skoldstam, L. Hagfors, G. Johansson. An experimental study of a Mediterranean diet intervention for patients with rheumatoid arthritis. Ann Rheum Dis, 62 (2003), pp. 208-214
Tedeschi, S.K., Costenbader, K.H. Is There a Role for Diet in the Therapy of Rheumatoid Arthritis?. Curr Rheumatol Rep 18, 23 (2016). https://doi-org.elibrary.einsteinmed.org/10.1007/s11926-016-0575-y
Nguyen, Y., Carine, S. et al. Mediterranean diet and risk of rheumatoid arthritis: findings from the French E3N-EPIC cohort study. Arthritis and Rheumatology. September 9, 2020. https://doi-org.elibrary.einsteinmed.org/10.1002/art.41487
Bhatt DL, Miller M, Brinton EA, Jacobson TA, Steg PG, Ketchum SB, Doyle RT Jr, Juliano RA, Jiao L, Granowitz C, Tardif JC, Olshansky B, Chung MK, Gibson CM, Giugliano RP, Budoff MJ, Ballantyne CM; REDUCE-IT Investigators. REDUCE-IT USA: Results From the 3146 Patients Randomized in the United States. Circulation. 2020 Feb 4;141(5):367-375. doi: 10.1161/CIRCULATIONAHA.119.044440. Epub 2019 Nov 11. PMID: 31707829; PMCID: PMC7004453.