Diet, Nutrition, and Rhinosinusitis: A Systematic Review of Dietary Interventions and Exposures

Background/Objectives: Rhinosinusitis (RS) is a prevalent inflammatory condition with substantial morbidity and variable response to standard therapies. Diet is a modifiable determinant of systemic inflammation, yet its role in sinonasal disease remains incompletely defined. Methods: A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Scopus, Cochrane Library, and Web of Science were searched from inception through 28 June 2026. Studies assessing dietary exposures or interventions in RS were included using predefined criteria. Risk of bias was assessed using ROBINS-I and Joanna Briggs Institute tools. Due to heterogeneity in study design and outcomes, findings were synthesized narratively. Results: Ten studies met inclusion criteria (5 adult, 4 pediatric, 1 mixed), including interventional and observational designs. Anti-inflammatory dietary patterns were associated with improved sinonasal outcomes. In children, Mediterranean diet adherence reduced recurrent inflammatory episodes, and reduced sugar intake improved sinus infection scores with decreased TNF-α concentrations. In adults, both allergen-guided elimination diets and a low-arachidonic acid, low-salicylate, high-fiber dietary intervention improved symptom severity, with accompanying improvements in endoscopic outcomes. Observational studies demonstrated that higher fruit intake was associated with lower RS prevalence, whereas higher fat intake, caloric intake, Dietary Inflammatory Index scores, frequent meals prepared away from home, and ultra-processed food intake were associated with increased disease risk or sinonasal symptom burden. Phenotype-specific associations included increased dietary salicylate sensitivity and food-triggered symptom exacerbation among patients with nasal polyposis. Conclusions: Dietary patterns and specific nutritional exposures are associated with RS outcomes across age groups. Anti-inflammatory dietary profiles demonstrate potential protective effects, whereas pro-inflammatory dietary patterns are associated with increased disease burden. However, the predominance of observational data and study heterogeneity limit causal inference. Well-designed prospective and randomized studies are needed to define the therapeutic role of dietary modification in RS.