Rheumatoid arthritis is a chronic autoimmune disease characterized by joint inflammation and pain. Several dietary interventions, with or without supplementation, are reported in the literature to support therapy to relieve classic symptoms such as pain, joint stiffness, swelling, fatigue, and weakness.
As is often the case, studies show significant differences in terms of types of dietary intervention and parameters examined to assess outcome: Mediterranean, anti-inflammatory, vegan/vegetarian, elemental and allergen-free diets have different effects and do not always lead to improvements.
A Cochrane review published in 2009 included 15 studies and evaluated the effects of diets on three parameters (pain, stiffness, and physical function) in 837 patients, concluding that comparing any diet with an ordinary one, there are benefits, but also 8% higher overall dropout rates in the diet groups compared with controls.
Eliminating certain foods from the diet such as red meat, gluten-containing foods, high-sugar foods, and alcohol may help relieve symptoms, but evidence on the effects of elimination diets is limited, and some authors have suggested that hypersensitivity to certain protein sources could lead to exacerbation of symptoms.
Although there is evidence on the pro-inflammatory effects of diets high in processed and red meat, studies have found no significant differences in symptoms when red meat was removed from the diet.
Gluten is also associated with increased inflammation, and studies in which wheat was removed from the diet showed significant improvements in Ritchie’s index and joint swelling.
Intervention studies with a gluten-free vegan diet also reported significant improvements in several parameters, but it is unclear whether improvements were observed as a result of gluten removal or because of the vegan diet itself.
A 2020 review reviewed 33 studies linking diet or dietary supplements to disease activity, concluding that several dietary components may influence disease activity through direct or indirect interactions with the immune system.
Long-chain omega-3 fatty acids found in fish may reduce the production of inflammatory eicosanoids, adhesion molecules, and cytokines; antioxidants may reduce oxidative stress and thus possibly symptoms and inflammation. In addition, dietary fiber, prebiotics, or probiotics could have beneficial effects on disease activity through modification of the microbiota.
Specific nutrients and alterations in the microbiota may also affect intestinal permeability, which in turn may influence the immune response. Finally, weight loss following dietary intervention may be beneficial, as obesity is associated with the most rapid progression of disability.
The results of this review also show potentially beneficial effects from supplements containing individual antioxidants and spices with high antioxidant capacity. The administered doses of spices in the included studies, about one teaspoon/day, could be achievable through diet alone.
Among the supplements evaluated, omega-3 fatty acids demonstrate the ability to improve symptoms such as pain and morning stiffness, as well as to reduce the dose of NSAIDs consumed.
Only two studies evaluated the efficacy of a dietary intervention in combination with Omega-3s. The first reported significant reductions in C-reactive protein, Tnf-α, and corticosteroids in participants following an anti-inflammatory diet or a Western diet with fish oil supplements, but the most significant improvements were found in the anti-inflammatory/Omega-3 diet group. In the second study, a Pufa-rich diet (P:S ratio 5: 0) in combination with Omega-3 supplementation (1.6 g Epa/day and 1.1 g Dha/day) resulted in significant benefits in terms of morning stiffness, Ritchie’s index, and grip strength. This indicates that the anti-inflammatory benefits of a diet in combination with Omega-3 may be superior to diet alone, and further research in this area is warranted.
Bibliography
Dietary interventions with or without Omega-3 supplementation for the management of rheumatoid arthritis: a systematic rReview. Nutrients 2021, 13(10), 3506
Rheumatoid arthritis and dietary interventions: systematic review of clinical trials. Nutr. Rev. 2020, 79, 410–428.
Do interventions with diet or dietary supplements reduce the disease activity score in rheumatoid arthritis? A systematic review of randomized controlled trials. Nutrients 2020, 12, 2991.
Intake of ω-3 polyunsaturated fatty acids in patients with rheumatoid arthritis: asystematic review and meta-analysis. Nutrition 2018, 45, 114–124.
Effectiveness and safety of dietary interventions for rheumatoid arthritis: a systematic review of randomized controlled trials. J Am Diet Assoc. 2010 May;110(5):727-35.
Dietary interventions for rheumatoid arthritis. Cochrane database Syst. Rev. 2009, 21, CD006400.
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