Association between dietary inflammatory index and Bell's palsy: a retrospective case-control study

Bell's palsy (BP) is an acute facial nerve disorder characterized by rapid-onset unilateral paralysis, in which inflammatory and immune-mediated processes are implicated. The Dietary Inflammatory Index (DII) quantifies the inflammatory potential of the diet and reflects systemic inflammatory burden. However, its association with BP has not been previously investigated.

This retrospective case-control study included 30 patients with newly diagnosed BP and 30 age- and sex-matched controls without a history of facial paralysis. Dietary intake was assessed using a validated food frequency questionnaire, and DII scores were calculated using standardized methodology. Group differences were analyzed using appropriate statistical tests. Multivariable logistic regression evaluated the association between DII and BP after adjustment for age, sex, and body mass index. Receiver operating characteristic (ROC) analysis assessed discriminatory performance.

Patients with BP had significantly higher DII scores than controls (2.54 ± 1.86 vs. 1.18 ± 1.33; p = 0.002). The BP group also exhibited higher intakes carbohydrates, total fat, saturated fat, monounsaturated fat, and sodium (all p < 0.01). Each 1-unit increase in DII score was independently associated with BP (adjusted OR = 1.70; 95% CI: 1.18-2.47; p = 0.005). ROC analysis demonstrated moderate discriminatory ability (AUC = 0.753; 95% CI: 0.626-0.879).

Higher dietary inflammatory potential is associated with Bell's palsy, indicating a more pro-inflammatory dietary profile; however, causality cannot be inferred.