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, PhD, from the Karolinska Institutet in Stockholm, and colleagues used data from the Swedish epidemiological investigation of RA to identify 1721 patients with incident RA (cases) and 3667 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% of the patients and 28.2% 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% (odds ratio [OR], 0.79; 95% confidence interval [CI], 0.65 to 0.96) vs 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% CI, 0.33 to 0.73), but there were no significant associations among women (OR, 0.94; 95% 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% CI, 0.54 to 0.88), but not rheumatoid factor-negative RA (OR, 0.96; 95% 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.