Improving allergic rhinitis symptoms through nutrition as an adjunct: a systematic review and meta-analysis on the efficacy of dietary supplements

Dietary supplements are increasingly explored as adjunctive strategies for allergic rhinitis (AR). This systematic review and meta-analysis evaluated the efficacy of dietary supplementation in improving AR symptoms and explored potential underlying mechanisms. A systematic PubMed search was conducted through May 2026 following Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Trials evaluating dietary interventions in AR were included. Meta-analyses were performed using DerSimonian-Laird random-effects models for studies reporting changes in Total Nasal Symptom Score (TNSS). Risk of bias was assessed using the RoB2 tool while publication bias was assessed using Egger’s test, and heterogeneity was quantified with the I 2 statistic. Ninety-three studies were included, with 26 eligible for meta-analysis. Interventions were classified into plant-based compounds, probiotics, vitamins, fatty acids, and other supplements. Most studies were assessed as low risk of bias (91.4%), with a small proportion (8.6%) raising some concerns. Significant reductions in TNSS were observed for probiotics (Standardized Mean Difference (SMD) = − 1.63, 95% CI − 2.59, − 0.66), plant-based compounds (SMD = − 1.24, 95% CI − 2.12, − 0.36), and vitamin D supplementation (SMD = − 2.79, 95% CI − 3.33, − 2.24). However, substantial heterogeneity existed across intervention types, formulations, and study methodologies. Mechanistic findings suggested potential roles in immune modulation, anti-inflammatory activity, and gut microbiota regulation, although these remain hypothesis-generating. Plant-based compounds, probiotics, and vitamin D may provide adjunctive benefits for improving AR symptoms. Nevertheless, findings should be interpreted cautiously given substantial heterogeneity, reliance on subjective outcomes, and potential small-study effects.