The Effect of the Mediterranean Diet on Disease Activity Markers (DAS28, CRP) in Patients with Rheumatoid Arthritis: A Systematic Review

Abstract

Rheumatoid Arthritis (RA) is a chronic autoimmune disease where patients frequently seek non-pharmacological adjuncts to standard care. The Mediterranean Diet (MD) has been proposed as a potential modulator of inflammation, yet evidence regarding its impact on objective clinical markers remains mixed. Objective: To evaluate the efficacy of the MD compared to control diets in reducing the Disease Activity Score-28 (DAS28) and C-Reactive Protein (CRP) in adult patients with RA. Methods: A systematic review of randomized controlled trials (RCTs) was conducted following PRISMA 2020 guidelines. Electronic databases (PubMed, Scopus, Web of Science, Cochrane Library) were searched for English and Polish studies. Eligibility criteria included adult RA patients, a minimum 4-week MD intervention, and quantitative reporting of DAS28 or CRP. Risk of bias was assessed using the Cochrane RoB 2 tool. Results: Three RCTs were included in the qualitative synthesis. Analysis revealed a divergence in outcomes based on intervention intensity. Trials providing food to ensure high adherence demonstrated statistically significant reductions in DAS28 and improvements in physical function. Conversely, trials relying solely on dietary advice showed no significant impact on composite scores. Effects on CRP were variable, likely influenced by the concurrent use of biologic therapies in modern cohorts.

Conclusion: The Mediterranean Diet is a beneficial adjunct strategy in RA, capable of improving disease activity and functional status, particularly when adherence is optimized. However, it does not replace pharmacotherapy, and its efficacy appears dose-dependent. Future research should focus on long-term structural outcomes and personalized nutrition.