TUESDAY, Sept. 11, 2018 (HealthDay News) -- High adherence to the Mediterranean diet score is tied to lower risk of rheumatoid arthritis (RA) in some populations, according to a study published online Aug. 9 in Arthritis Research & Therapy.
Kari Johansson, Ph.D., from the Karolinska Institutet in Stockholm, and colleagues used data from the Swedish epidemiological investigation of RA to identify 1,721 patients with incident RA (cases) and 3,667 controls, matched on age, gender, and residential area. The Mediterranean diet score was determined based on a 124-item food frequency questionnaire.
The researchers found that 24.1 percent of the patients and 28.2 percent of the controls had high adherence to the Mediterranean diet (a score between 6 and 9 on a 9-point scale). High adherence to the diet reduced the odds of developing RA by 21 percent (odds ratio [OR], 0.79; 95 percent confidence interval [CI], 0.65 to 0.96) versus low adherence (a score between 0 and 2), after adjusting for body mass index, educational level, physical activity, use of dietary supplements, energy intake, and smoking. For men, the OR was even lower (OR, 0.49; 95 percent CI, 0.33 to 0.73), but there were no significant associations among women (OR, 0.94; 95 percent CI, 0.74 to 1.18). There was an association between high diet score and low risk of RA in rheumatoid factor-positive (OR, 0.69; 95 percent CI, 0.54 to 0.88), but not rheumatoid factor-negative RA (OR, 0.96; 95 percent CI, 0.68 to 1.34).
"We need to acknowledge that the mechanisms and impact of potential dietary guidelines might have to differ between RA sub-groups," the authors write.