Mediterranean diet and remission in rheumatoid arthritis: findings from the EIRA study

ABSTRACT Objectives Newly diagnosed patients with rheumatoid arthritis (RA) often ask whether diet can influence disease activity, yet evidence remains limited. We investigated whether prediagnosis adherence to a Mediterranean diet is associated with remission 6 months after diagnosis. Methods We included incident RA cases from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study, with follow-up through the Swedish Rheumatology Quality Register. Remission at 6 months was defined using 5 alternative criteria (eg, 28-joint Disease Activity Score [DAS28], Boolean or combinations of their components). Prediagnosis diet was measured with a 124‑item food‑frequency questionnaire, and Mediterranean diet adherence was scored from 0 to 9. Modified Poisson regression estimated adjusted risk ratios (RRs) and 95% CIs for remission, comparing the highest vs the lowest Mediterranean diet tertiles. Analyses were stratified by RA autoantibody status (rheumatoid factor and/or anticitrullinated protein antibodies). Results Among 1510 incident RA cases (77% autoantibody-positive), higher Mediterranean diet adherence was associated with DAS28 remission in autoantibody-positive RA (59% vs 49%, RR: 1.24; CI: 1.07-1.44), but not in autoantibody-negative RA (49% vs 58%, RR: 0.84; CI: 0.65-1.09). A similar pattern appeared for Boolean remission (autoantibody-positive: 35% vs 28%, RR: 1.24; CI: 0.98-1.57; autoantibody-negative: 31% vs 32%, RR: 1.00; CI: 0.67-1.49). In contrast, Mediterranean diet adherence was not associated with minimal objective inflammatory activity (28-swollen joint count ≤ 1 and C-reactive protein ≤ 1 mg/dL). Conclusions Greater adherence to a Mediterranean diet at RA onset is associated with higher chances of remission in autoantibody-positive, but not in autoantibody‑negative RA.