The relationship between dietary inflammatory index and metabolic syndrome in patients with rheumatoid arthritis

Purpose Inflammation plays a significant role in incidence of metabolic syndrome (MetS), whose risk can be reduced through modifying the diet. Considering the importance of incidence of MetS among patients with rheumatoid arthritis (RA), this study aims to determine the relationship between dietary inflammatory index (DII) and MetS in these patients. Design/methodology/approach This study was performed on 261 adults 35–65 years of age suffering from RA. The patients were among the participants in Ravansar non-communicable disease prospective study. DII was calculated based on food frequency questionnaire. The components of MetS were measured according to the protocol of prospective epidemiological research studies in Iran cohort. Data analysis was carried out using univariate and multivariate logistic regression model by modifying the confounding variables. Findings In patients with RA, prevalence of MetS was 37.5%. The mean of DII in RA patients with MetS and without MetS was −2.3 ± 1.5 and −2.2 ± 1.6, respectively, with no significant difference between two groups. After modifying the variables of age and gender, the odds of increasing waist circumference (WC) were near 1.9 times greater in the fourth quartile (pro-inflammatory diet) compared to the first quartile of DII (anti-inflammatory diet) (P = 0.03). The odds of developing hypertension was approximately 1.3 times greater in the fourth compared to the first quartile of DII (P = 0.034). The odds of developing MetS increased by 27% in the fourth quartile in comparison to the first one, though this increase was not statistically significant. Originality/value In RA patients, with increase in DII score, the WC and blood pressure had increased. The DII had no significant relationship with MetS. Further studies are essential across larger populations to confirm the findings.