Nutrition and Diet in Rheumatoid Arthritis, Axial Spondyloarthritis, and Psoriatic Arthritis: A Systematic Review

Kaat Van Den Bruel¹Myroslava Kulyk^2*Barbara Neerinckx^1,2Kurt De Vlam^1,2

• ¹Department of Rheumatology, UZ Leuven, Leuven, Belgium
• ²Skeletal Biology and Engineering Research Center, Department of Development and Regeneration, KU Leuven, Leuven, Belgium

1. This systematic review aims to analyze the effects of specific diets, dietary supplements, and probiotics on disease activity, inflammation, and immune response in patients with rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), and psoriatic arthritis (PsA). A systematic literature search was conducted across PubMed, Embase, and Cochrane Library, including randomized clinical trials (RCTs) of patients with RA, axSpA, and PsA undergoing specific dietary or nutritional interventions. EndNote and Rayyan software facilitated duplicate removal and screening, and study quality was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist for Primary Research, with main outcomes focusing on changes in immune response, inflammatory biomarkers, and disease activity. Of the 2250 screened articles, 49 studies met the inclusion criteria. Our findings indicate that various dietary interventions, including vegan, anti-inflammatory, and Mediterranean diets, improved disease activity, quality of life, and inflammation markers in RA. For axSpA, evidence was limited, though polyunsaturated fatty acids (PUFAs) supplementation showed potential benefits. Nutritional supplements, such as PUFAs, vitamin D, pomegranate extract, and ginger, exhibited anti-inflammatory and immunomodulatory effects across the conditions. Probiotics and synbiotics demonstrated variable impacts on immune markers, with synbiotics notably reducing interleukin-17 (IL-17) levels. In PsA, a hypocaloric diet supplemented with omega-3 (n-3 PUFA) fatty acids was associated with reductions in disease activity. In conclusion, dietary interventions and supplementation may contribute to managing chronic arthritis by influencing inflammatory and immune pathways. However, due to the significant heterogeneity in study designs, interventions, and outcomes, a meta-analysis was not performed, and findings are synthesized narratively. While these findings suggest potential benefits as adjuncts to pharmacological treatment, further high-quality RCTs are needed to confirm their long-term clinical impact. 2.