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

Participants in the intervention group will take yeast β-glucan capsules daily. Each capsule contains 250 mg of yeast β-glucan, along with an appropriate amount of maltodextrin and silicon dioxide. All participants in the intervention group will take two capsules once daily, swallowed with warm water after meals.

Participants in the placebo group will take two placebo capsules once daily in the same manner. The placebo capsules are identical to the intervention capsules in form, taste, appearance, and packaging, but contain only maltodextrin and a small amount of silicon dioxide.