Monounsaturated fatty acids might be key factors in the Mediterranean diet that suppress rheumatoid arthritis disease activity: The TOMORROW study

Background & aims: The Mediterranean diet is reportedly effective in suppressing disease activity in rheumatoid arthritis (RA), but the key elements responsible for this effect remain unknown. The presented study therefore aimed to identify such elements.

Methods: This study included 208 consecutive patients with RA (RA group) and 205 age- and sex-matched healthy volunteers (controls) from the prospective "TOMORROW" cohort study that has been ongoing since 2010 were included in this study. Food and nutrient intake was assessed using the brief self-administered diet history questionnaire (BDHQ), Mediterranean diet scores were calculated based on intake by controls and disease activity was determined from disease activity scores in 28 joints and erythrocyte sedimentation rates (DAS28-ESR).

Results: Intake of monounsaturated fatty acids (MUFA) was significantly lower in the RA, than in the control group (P = 0.003) and the ratio of consumed monounsaturated to saturated fatty acid (MUFA/SFA) significantly differed within the RA group after being sub-classified according to DAS28-ESR. Moreover, DAS28-ESR significantly correlated with MUFA/SFA intake after age adjustment (R = -0.228, P < 0.01). Logistic regression analysis selected high MUFA intake as an independent predictor of remission in the RA group with borderline boundary significance (odds ratio, 1.97; 95% CI, 0.98-3.98; P = 0.057). Changes in DAS28-ESR between 2010 and 2011 significantly correlated with MUFA/SFA intake after age adjustment (R = 0.180, P = 0.01).

Conclusions: Daily MUFA intake, a component of the Mediterranean diet score, might suppress disease activity in RA patients.