Western and Healthy Dietary Patterns and Risk of Rheumatoid Arthritis: A Case-Control Study

Background and Objectives: Rheumatoid arthritis (RA) is an inflammatory autoimmune disease characterized by swelling, stiffness and pain in body joints. Based on the epidemiological studies, RA is less severe in Southern Mediterranean regions, where fish, olive oil, fruits and vegetables are consumed in great quantities. Materials and Methods: This study was carried out in a case-control design. Totally, 100 RA patients (case group) and 100 age, gender and body mass index (BMI) healthy individuals (control group) were participated in the study. Dietary intakes were estimated using validated 160-item semi-quantitative food frequency questionnaire (FFQ). Food items of FFQ were grouped into 20 groups and dietary patterns were detected using principal component factor analysis. Associations between the adherence to dietary patterns and risk of RA were reported using logistic regression. Results: In general, two dietary patterns were detected, including Western dietary pattern, which was high in sweet snacks, high-fat meats, refined grains, high-fat dairies and salty snacks, and healthy dietary pattern, which was high in fishes, low-fat dairies, fruits, vegetables and olives. The RA patients had a significantly higher Western diet score than that the controls had (P < 0.001). However, no significant differences were seen in scores of healthy diet between the groups. The Western dietary pattern showed a significant positive association with RA either in the crude model (OR = 2.01, P < 0.001) or after adjustments of age, gender, education level, marital status, income, physical activity, smoking, BMI, dietary intake of vitamin E, saturated fatty acids and polyunsaturated fatty acids (OR = 4.28, P < 0.001). In contrast, the healthy dietary pattern showed an inverse significant association only after adding the highlighted parameters to the model (OR = 0.55, P = 0.003). Conclusions: This study showed a positive association between the Western dietary pattern and RA.