The influence of Mediterranean diet in rheumatoid arthritis : A monocenter cross-sectional study

Background/Purpose: Mediterranean diet (MD) is considered a well-balanced and potentially anti-inflammatory diet characterized by high consumption of olive oil, unrefined cereals, fresh or dried fruit and vegetables, fish, dairy products, meat and with a moderate amount of red wine. Currently, there is conflicting data for the benefits of MD in rheumatoid arthritis (RA), and not enough evidence to support a role of MD in the prevention and treatment of RA. The aim of our study was to evaluate the association between MD adherence and disease activity, general health (GH) and comorbidities in patients with RA. Methods: Consecutive patients with RA (ACR/EULAR Criteria 2010) were enrolled in this cross-sectional study. For each patient, Disease Activity Score on 28 joints (DAS28), Simple Disease Activity Index (SDAI), patient GH and a self-reported questionnaire called MD score were recorded. The association between MD score and the above mentioned variables was assessed through univariate regression models (MD score as response variable and the variables of interest as independent variables). Results from each model were reported in terms of: 1) test of association (Likelihood Ratio test, with a Chi-square distribution); 2) categorical independent variables, estimated differences of mean MD score between groups, with respective 95% CI; 3) numerical independent variables, estimate of correlation coefficient and regression slope coefficient, with respective 95% CI. The analysis was performed using the R software. Results: 205 RA patients (197 Italian) were enrolled: median age at visit 53 (q1-q3: 44-59) years, age at onset 38 (q1-q3: 28-47), disease duration 12 (q1-q3: 7-19), female 80.49%, rheumatoid factor and/or anti–citrullinated protein antibody positivity 58.54%, radiographic damage 41.79%. Comorbidities were also assessed: gastrointestinal 19% (gastro-esophageal reflux disease; inflammatory bowel disease; gastritis; esophagitis), chronic renal failure 1%, arterial hypertension 21.95%, diabetes mellitus 3.9% and coronary artery disease 1.95%. A significant positive correlation was found between MD score and GH, as shown in the table. This suggests a low/moderate tendency of having better GH with higher MD score. Although not statistically significant, a negative correlation was found with DAS28 and SDAI, suggesting an association between higher MD score with lower disease activity. Among comorbidities, a significant difference of mean MD score values between subjects with and without arterial hypertension was also found (mean difference -2.0 CI: -3.7, -0.2; p=0.029). Conclusion: In this Italian RA cohort, the adherence to MD was significantly associated with a better GH, but higher MD score was not significantly associated with lower disease activity. Arterial hypertension was the only comorbidity associated with lower MD score, probably due to the fact that the prevalence of the other comorbidities was low. Our study suggests an overall beneficial effect of MD in RA patients. Further studies are needed to better understand the impact of lifestyle modification (e.g. diet) in achieving RA disease control.