Study of the Preventive Effects and Mechanisms of Yeast β-Glucan on Upper Respiratory Tract Infections

This study is designed as a randomized, double-blind, placebo-controlled human intervention trial targeting a population of university students with persistent allergic rhinitis (AR) symptoms. The primary objective is to evaluate the preventive effect and underlying mechanisms of yeast β-glucan on upper respiratory tract infections (URTIs), providing scientific evidence for the prophylactic use of prebiotics in high-risk populations. All participants will be stratified by sex and body mass index (BMI), and then randomly assigned to either the yeast β-glucan group or the control group. During the 15-week study period-including a 1-week run-in phase, a 12-week intervention phase, and a 2-week follow-up phase-participants in the intervention group will take two yeast β-glucan capsules daily after meals, while the control group will take two placebo capsules with identical appearance, taste, and packaging. Participants will be monitored daily for the occurrence of URTIs. In the event of an infection, the Wisconsin Upper Respiratory Symptom Survey (WURSS-24) will be used to assess symptom severity and duration. Medication use, including dosage, frequency, and timing, will also be recorded. Weekly follow-ups will assess changes in Total Nasal Symptom Score (TNSS), Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), and adverse events. In addition, participants will undergo comprehensive follow-up assessments at Week 0 and Week 12, including TNSS and RQLQ questionnaires, a 3-day dietary intake survey, anthropometric measurements (e.g., height, weight, body fat percentage), and biological sample collection (blood, urine, and stool samples).