This study is designed as a randomized, double-blind, placebo-controlled human intervention trial among university students with persistent allergic rhinitis (AR) symptoms. The aim is to evaluate the effectiveness of yeast postbiotics in alleviating persistent AR symptoms and to explore the potential mechanisms by which yeast postbiotics modulate the gut microbiota to improve AR-related outcomes. A stratified randomization method will be applied to assign participants into the yeast postbiotic group and the placebo group. Stratification will be based on(1) Sex (male/female), and (2) Physician-diagnosed AR status (yes/no, based on self-reported clinical history), ensuring comparability between the two groups. During the intervention period, participants in the yeast postbiotic group will take two capsules of yeast postbiotic supplements daily after meals, while the placebo group will take two placebo capsules, identical in appearance and composition except without the active ingredients. The total study duration is 15 weeks, including a 1-week run-in period, 12-week intervention, and 2-week follow-up after the intervention.
All participants will be asked to complete a daily nasal symptom score (TNSS) and report any adverse events. At week 0, week 4, and week 12, follow-up assessments will be conducted, including: symptom and quality-of-life questionnaires (e.g., VAS, RQLQ), dietary intake surveys, anthropometric measurements (height, weight, body fat percentage), and biological sample collection (including blood, urine, saliva, and feces). Additionally, saliva samples will be collected specifically at week 2 of the intervention to assess mucosal immune markers.