Dietary inflammatory potential and dimensions of eating disorder psychopathology among Iranian university students: a cross-sectional study

Dietary inflammatory potential has been associated with several mental health outcomes, but its relationship with eating disorder (ED) psychopathology remains unclear. This study examined the association between the empirically derived food-based dietary inflammatory index (FDII) and ED psychopathology among university students. This cross-sectional study included 271 dormitory-residing students aged 18–40 years from Tehran University of Medical Sciences, Iran. Dietary intake was assessed using a validated 168-item food frequency questionnaire. An adapted dietary inflammatory score was calculated using food-group factor loadings derived from an Iranian dietary-pattern study. ED psychopathology was assessed using the Persian version of the Eating Disorder Examination Questionnaire (EDE-Q). The primary analysis examined the association between the FDII score, analyzed continuously per 1-SD increase, and the continuous global ED psychopathology score using multivariable linear regression. Secondary analyses examined ED psychopathology subscales and comparisons across FDII tertiles. An exploratory logistic regression analysis examined the association between FDII and elevated ED psychopathology scores, defined using the study-specific 85th-percentile threshold. In the primary continuous analysis, each 1-SD increase in the FDII score was associated with a 0.13-point higher global ED psychopathology score (95% CI: 0.007–0.25; P = 0.04) after adjustment for confounders. However, this association was attenuated and no longer statistically significant in the sensitivity analysis excluding BMI (B = 0.111, 95% CI: −0.019 to 0.241; P = 0.097), whereas associations with Shape Concern and Weight Concern remained statistically significant. The dietary score was also positively associated with Eating Concern (B = 0.12, 95% CI: 0.006–0.24; P = 0.04), Shape Concern (B = 0.24, 95% CI: 0.07–0.41; P = 0.006), and Weight Concern (B = 0.20, 95% CI: 0.04–0.36; P = 0.01), but not Restraint ( P = 0.44). Adjusted ED psychopathology scores showed significant linear trends across FDII tertiles for the global score and most subscales (P for trend ≤ 0.03), although restraint eating showed a significant difference between tertiles (adjusted P = 0.02) without a linear trend ( P = 0.8). In exploratory logistic regression, no statistically significant association was observed between FDII tertiles and elevated ED psychopathology scores after adjustment. Higher values of the FDII were associated with higher continuous global and several domain-specific ED psychopathology scores in the sample of university students. These findings should be interpreted as cross-sectional associations rather than evidence of causality or clinical eating-disorder risk. Prospective studies using validated biomarker-derived inflammatory indices and inflammatory biomarkers are warranted to clarify temporality and underlying mechanisms.