Study of the Preventive Effects and Mechanisms of Yeast β-Glucan on Upper Respiratory Tract Infections
Phase: NA
Conditions: Upper Respiratory Tract Infections
Sponsor: LanZhou University

 
 
 
 
 
 
 
Study of the Preventive Effects and 
Mechanisms of Yeast β-Glucan on Upper 
Respiratory Tract Infections 
 
 
 
 
 
 
 
 
 
2025.6.10 
 
 

Study Protocol and Statistical Analysis Plan: 
 
Study of the Preventive Effects and Mechanisms of Yeast β-Glucan 
on Upper Respiratory Tract Infections 
1 Background 
Upper respiratory tract infections (URTIs) are acute mucosal infectious diseases caused by 
pathogens invading the respiratory mucosa, leading to disruption of the epithelial barrier, activation 
of the immune system, and subsequent inflammatory responses. Clinical manifestations include 
nasal congestion, rhinorrhea, sore throat, cough, and hoarseness. Common causative pathogens 
include rhinoviruses, coronaviruses, influenza viruses, adenoviruses, and respiratory syncytial virus. 
Although most URTIs are self-limiting, their high incidence, recurrence, and transmissibility—
especially in densely populated environments such as schools and workplaces—pose a considerable 
public health burden. Allergic rhinitis (AR) is a chronic inflammatory disease of the upper 
respiratory tract mediated by immunoglobulin E (IgE), with typical symptoms including nasal 
itching, sneezing, watery nasal discharge, and nasal obstruction. Due to the persistent inflammatory 
state of the nasal mucosa in AR patients, along with impaired epithelial barrier function, reduced 
ciliary activity, and diminished secretion of secretory immunoglobulin A (sIgA), the defense 
capacity against viral and bacterial pathogens is significantly weakened. As a result, AR patients are 
more susceptible to recurrent URTIs. Additionally, the seasonal peak of AR often overlaps with the 
high-incidence period of URTIs, further increasing the risk of infection. Therefore, individuals with 
AR can be considered a high-risk population for URTIs and are ideal candidates for evaluating 
preventive interventions. 
The human gastrointestinal tract harbors a vast and diverse microbial community that plays a 
vital role in maintaining immune homeostasis, mucosal barrier integrity, and protection against 
infections. As potential modulators of gut microbiota, probiotics and prebiotics have been widely 
used to improve disease phenotypes and clinical outcomes associated with dysbiosis. Probiotics are 
live microorganisms which, when administered in adequate amounts, confer health benefits to the 
host. Several studies have shown that probiotics can reduce the incidence, duration, and severity of 
common colds and sore throat symptoms. A 12-week randomized controlled trial demonstrated that 

probiotics could lower the occurrence of URTIs, possibly by enhancing serum interferon-gamma 
(IFN-γ) and intestinal sIgA levels. 
Prebiotics are substrates that are not digestible or absorbable by the host but can be selectively 
utilized by beneficial microorganisms to modulate the composition and/or activity of the gut 
microbiota, thereby conferring health benefits. However, studies focusing on prebiotics for the 
prevention of URTIs remain relatively limited. Yeast β-glucan, a high-molecular-weight natural 
polysaccharide and a commonly used prebiotic, has been shown to possess multiple biological 
activities, including immunomodulatory, anti-inflammatory, and gut microbiota-regulating effects. 
Some evidence suggests that yeast β-glucan can improve immune function and reduce the duration 
and severity of cold and flu symptoms in healthy young and middle-aged adults. However, no 
relevant studies have been reported in populations with AR. 
In summary, given the increased frequency of URTIs in the post-pandemic era, there is an 
urgent need to identify effective strategies for prevention. Preliminary evidence indicates that yeast 
β-glucan may have preventive effects against URTIs, but the current body of research is limited, 
particularly in AR populations who are more susceptible. Therefore, this study aims to conduct a 
randomized, double-blind, placebo-controlled intervention trial among college students with 
persistent AR symptoms to evaluate the preventive effect and underlying mechanisms of yeast β-
glucan on URTIs, and to provide scientific evidence supporting its prophylactic use in high-risk 
populations. 
2 Objectives 
(1) To evaluate the effect of yeast β-glucan on the incidence and severity of URTIs. 
(2) To explore the potential mechanisms underlying the preventive effect of yeast β-glucan on 
URTIs. 
3 Design and Methods 
3.1 Participants 
This study plans to recruit current students at Lanzhou University who have persistent AR 
symptoms as research participants. 
3.1.1 Inclusion Criteria: 
Participants must meet all of the following conditions:(1) Aged between 18 and 35 years; (2) 
Meet the diagnostic criteria for persistent AR as defined in the Chinese Guidelines for the Diagnosis 

and Treatment of Allergic Rhinitis (2022, Revised Edition): ①Symptoms: At least two of the 
following—paroxysmal sneezing, watery rhinorrhea, nasal itching, and nasal congestion—lasting 
or occurring for more than 1 hour per day; may be accompanied by ocular symptoms such as tearing, 
itchy eyes, and redness; ②Persistent AR: Symptom onset on ≥4 days per week and duration ≥4 
consecutive weeks; (3) Have not used probiotics, prebiotics, synbiotics, antihistamines, 
corticosteroids, or immunosuppressants within one month prior to screening; (4) Willing and able 
to maintain regular levels of physical activity and dietary patterns throughout the study period; (5) 
Provide signed informed consent voluntarily. 
3.1.2 Exclusion Criteria: 
Participants will be excluded if they meet any of the following:(1) Use of antibiotics, osmotic 
laxatives (e.g., magnesium sulfate, lactulose), anthraquinone-based laxatives (e.g., rhubarb, aloe, 
senna), or gastrointestinal prokinetic agents (e.g., metoclopramide, domperidone, cisapride) within 
one month prior to screening; (2) Diagnosis of non-allergic rhinitis (including vasomotor, infectious, 
hormonal, or drug-induced rhinitis), nasal polyps, severe nasal septum deviation, cerebrospinal fluid 
rhinorrhea, or aspirin-exacerbated respiratory disease (AERD); (3) Uncontrolled coexisting allergic 
conditions such as sinusitis, otitis media, allergic asthma, or atopic dermatitis; (4) History of serious 
gastrointestinal disorders (e.g., chronic diarrhea, inflammatory bowel disease), or gastrointestinal 
endoscopy within the past month; (5) Presence of congenital genetic disorders, primary 
immunodeficiency diseases, severe systemic illnesses, or malignant tumors; (6) Receipt of influenza 
vaccination within the past 6 months; (7) Pregnant or lactating women, or individuals planning to 
become pregnant in the near future. 
Individuals meeting all inclusion criteria and none of the exclusion criteria will be enrolled as 
study participants for intervention. 
3.2 Study Design 
This study is designed as a randomized, double-blind, placebo-controlled human intervention 
trial. All enrolled 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 intervention 
period, participants in the yeast β-glucan group will take two capsules daily after meals, while 
participants in the control group will take two placebo capsules. The total study duration is 15 weeks, 
consisting of a 1-week run-in period, a 12-week intervention period, and a 2-week follow-up period. 

3.3 Intervention Protocol 
Participants in the intervention group will take two yeast β-glucan capsules per day, with each 
capsule containing 250 mg of yeast β-glucan along with an appropriate amount of maltodextrin and 
silicon dioxide. The control group will take an equal number of placebo capsules daily, which are 
identical in form, taste, appearance, and packaging to the intervention product but contain only 
maltodextrin and a small amount of silicon dioxide. All participants will take two capsules once 
daily with warm water after meals. 
3.4 Safety Assessment of Yeast β-Glucan 
The yeast β-glucan used in this study is supplied by Angel Yeast Co., Ltd. In 2010, the Chinese 
Ministry of Health officially approved yeast β-glucan as a new food ingredient, indicating that it 
can be safely used in various food products. Therefore, yeast β-glucan is considered to have a 
favorable safety profile. Nevertheless, any adverse events will be continuously monitored during 
the study and reported and handled in accordance with ethical requirements. 
3.5 Randomization, Blinding, and Unblinding 
Participants will be randomly assigned to either the yeast β-glucan group or the control group, 
ensuring balance in sex and BMI between the groups. The randomization sequence will be 
concealed using sequentially numbered, opaque sealed envelopes. Group assignment will occur 
after participants provide informed consent and pass the initial screening. 
Both participants and investigators will be blinded to group allocation. Only the study designer 
will have access to the randomization codes. All intervention products and sample labels will be 
coded identically to prevent accidental unblinding. In the event of a serious adverse reaction 
potentially related to the intervention, the affected participant will be unblinded and withdrawn from 
the trial. 
3.6 Sample Size Estimation and Statistical Analysis 
The sample size was calculated using the standard formula for randomized controlled trials： 
𝑁=
(𝑍1−𝛼√2𝑝̅(1 −𝑝̅) + 𝑍𝛽√𝑝1(1 −𝑝1) + 𝑝2(1 −𝑝2))
2
(𝑝1 −𝑝2)2
 
Using URTIs incidence as the primary outcome, with parameters α = 0.05, β = 0.1, p₁ = 0.50, 
and p₂ = 0.20, the required sample size is approximately N ≈ 42 per group, or 84 participants in total. 
Considering an anticipated 15% dropout rate, a total of 96 participants with persistent AR will be 

recruited. 
All statistical analyses will be conducted using SAS version 9.4. Continuous variables will be 
expressed as means ± standard deviation, while ordinal and categorical variables will be expressed 
as proportions. Group comparisons will be conducted using t-tests or Kruskal–Wallis rank-sum tests 
for continuous variables, and Chi-square or Fisher’s exact tests for categorical variables. A two-
sided p-value of < 0.05 will be considered statistically significant. 
For outcomes measured at multiple time points (e.g., weeks 0 and 12), such as Total Nasal 
Symptom Score (TNSS) and inflammatory cytokine levels, linear mixed-effects models (LMMs) 
will be used to assess the effects of time, group, and their interaction. Post hoc analyses will compare 
the trajectories of changes between the intervention and control groups at each time point. 
3.7 Outcome Measures 
3.7.1 Primary Outcome 
Incidence of URTIs: Occurrence of upper respiratory tract infections (URTIs) will be 
monitored daily via participant self-report questionnaires. 
3.7.2 Secondary Outcomes 
(1) Wisconsin Upper Respiratory Symptom Survey (WURSS-24): In the event of a URTI 
episode, the WURSS-24 questionnaire will be used to assess symptom severity and its impact on 
quality of life. 
(2) Total Nasal Symptom Score (TNSS): TNSS evaluates the severity of four nasal symptoms: 
nasal itching, sneezing, rhinorrhea, and nasal congestion. Each symptom is scored from 0 to 3, with 
a total score ranging from 0 to 12. A higher score indicates more severe symptoms. 
(3) Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ): The RQLQ consists of 28 items 
across seven domains including daily activities, sleep, nasal/ocular symptoms, and emotional impact. 
Each item is scored from 0 to 6, with higher scores indicating greater impairment. The effect of 
intervention on quality of life will be assessed by comparing scores before and after the intervention. 
(4) Inflammatory Cytokines (IFN-γ, IL-4, IL-10, IL-6, TNF-α): Fasting plasma levels of 
inflammatory cytokines will be measured using high-sensitivity ELISA kits. The ratio of IFN-γ to 
IL-4 will be calculated to indirectly reflect Th1/Th2 immune balance. 
(5) These will be measured using an automated biochemical analyzer to evaluate systemic 
inflammation and liver and kidney function, serving as safety monitoring indicators. 

(6) Fecal Biomarkers: Gut microbiota composition will be assessed using 16S rRNA gene 
amplicon sequencing. Short-chain fatty acids (SCFAs) will be quantified via gas chromatography–
mass spectrometry (GC-MS). Fecal sIgA will be measured by ELISA. Bristol stool form scale will 
be used to evaluate changes in bowel habits and constipation improvement. 
3.8 Adverse Events 
All adverse events (AEs) occurring during or after the intervention period will be recorded, 
including subjective discomfort, symptom exacerbation, and laboratory abnormalities. Serious 
adverse events (SAEs) refer to medical incidents that result in death, life-threatening conditions, 
hospitalization, or significant functional impairment. All AEs will be graded according to the NCI-
CTCAE v5.0 criteria. Investigators will assess the causality between each event and the intervention 
(e.g., definitely related, possibly related, unrelated), and document all findings in the case report 
form (CRF) for final statistical analysis. In the event of an SAE, the research team will report it in 
writing to the Ethics Committee and regulatory authority within 24 hours and manage it promptly 
as per ethical guidance. During the study, participants will be followed up weekly, and investigators 
will actively inquire about and record any potential adverse events. 
3.9 Ethical Considerations 
This study has been approved by the Ethics Committee of the School of Public Health, Lanzhou 
University (Approval No.: IRB25041502). All participants will sign written informed consent prior 
to enrollment. The consent form will include details regarding the study objectives, methods, 
potential risks and benefits, AE management, and follow-up plan. 
Participants are free to withdraw from the study at any time without any reason and without 
affecting their medical care. All collected data will be anonymized and securely stored for research 
purposes only, ensuring confidentiality and data protection. 
If any adverse events occur due to the intervention, the research team will be responsible for 
providing appropriate medical support and treatment. The study will be conducted under continuous 
oversight by the Ethics Committee, in compliance with the Declaration of Helsinki, Good Clinical 
Practice (GCP), and relevant national regulations. 
4 Procedures 
4.1 Participant Recruitment, Informed Consent, and Baseline Survey 
Participants will be recruited through advertisements or posters at Lanzhou University. 

Interested volunteers will be asked to complete a screening questionnaire. Based on predefined 
inclusion and exclusion criteria, preliminary eligibility will be assessed. Those who pass the initial 
screening will be invited for a face-to-face interview with the research team, during which the study 
objectives, procedures, interventions, potential risks, and expected benefits will be fully explained. 
Participants who provide written informed consent after understanding the study details will be 
formally enrolled. A total of approximately 96 participants will be recruited. All participants will be 
assigned a unique ID code to ensure data confidentiality and for follow-up tracking. 
4.2 Baseline Assessments and Sample Collection 
Before randomization and intervention, all enrolled participants will complete the following 
baseline assessments: 
(1) Questionnaires: Including demographic information (age, gender, ethnicity, lifestyle habits), 
allergen exposure, allergic history, medical and family history, TNSS, RQLQ, and dietary intake 
assessment. 
(2) Anthropometric Measurements: Height, weight, body fat percentage. 
(3) Blood Sampling: For immune and inflammatory biomarker analysis. 
(4) Fecal Sampling: For gut microbiota profiling via 16S rRNA sequencing. 
4.3 Randomization 
Participants will be randomly assigned to either the yeast β-glucan group or the placebo group. 
Randomization will be stratified to ensure balance between the groups in terms of sex and BMI. 
4.4 Intervention 
Participants in the yeast β-glucan group will take two capsules daily, each containing yeast β-
glucan. The placebo group will receive two capsules identical in form, taste, appearance, and 
packaging, but without active ingredients. Each bottle contains 90 capsules, and participants will 
receive two bottles for the intervention period. During the trial, all participants are instructed not to 
consume any other probiotics, prebiotics, or synbiotics, and to maintain their usual dietary habits 
and physical activity levels. After the intervention period, participants in the placebo group will 
receive yeast β-glucan capsules as a post-trial nutritional benefit to ensure ethical fairness. 
4.5 Follow-up 
4.5.1 Follow-up Components: 
(1) Participants will be followed up at week 0 and week 12 for questionnaire assessments 

(TNSS, RQLQ), dietary surveys, anthropometric measurements (height, weight, body fat), and 
sample collection (blood, urine, feces). 
(2) Daily monitoring for URTI symptoms will be conducted. In the event of URTIs, WURSS-
24 will be administered to assess symptom severity and duration, along with medication use (type, 
dose, and timing). All participants will be trained prior to baseline on proper questionnaire 
completion to ensure accuracy and consistency. 
(3) Adherence Monitoring: Participants must submit daily photos of capsule intake via the 
designated survey platform or study group chat. Investigators will verify remaining capsules during 
each follow-up to calculate adherence. Cases of missed or discontinued use will be recorded and 
evaluated for potential exclusion. 
4.5.2 Data Collection Procedures: 
(1) Basic Information & Physical Measures: Conducted face-to-face in the morning while 
fasting at week 0 and week 12. Fecal samples will also be collected one week after the intervention. 
①Basic Information Survey：A structured face-to-face questionnaire will be administered to 
collect participants’ basic demographic and lifestyle information. The questionnaire includes: 
Personal Information: Name, sex, age, etc. 
Lifestyle factors: Physical activity, smoking status, alcohol consumption. 
Medical history: Past diseases, family history of allergic or chronic diseases. 
Allergen exposure history: Self-reported sensitization or known allergens. 
URTIs history: Frequency and severity of past upper respiratory tract infections. 
②Physical Measurements： Standardized anthropometric measurements will be performed to 
assess: Height, weight, waist circumference, hip circumference, and blood pressure. BMI (Body 
Mass Index) will be calculated as: BMI=Weight (kg)/Height (m2). Values will be recorded to two 
decimal places (kg/m²). 
③Biological Sample Collection： 
Blood Sample: Fasting venous blood (10 mL) will be collected by a trained nurse. Participants 
must fast for 10–12 hours prior to blood draw. After standing at room temperature for 3–5 minutes, 
blood samples will be centrifuged at 3000 rpm for 10 minutes, and the plasma will be aliquoted into 
pre-labeled EP tubes and stored at −80°C for subsequent analysis. 
Fecal Sample: Participants will collect stool samples using sterile cryotubes. The central 

portion of the stool will be collected to avoid contamination by urine or toilet water. Samples from 
participants with diarrhea or loose stools will be excluded. Fecal samples will be transferred to a 
−80°C freezer within 1 hour of collection. 
(2) Dietary Intake: Three-day dietary records will be completed before and after the 
intervention (including two weekdays and one weekend day), detailing all food and beverage 
consumption, including brand names where applicable. Standardized training and food atlas tools 
will be provided. Completed records will be reviewed daily by the research team, with missing or 
unclear entries clarified immediately. 
4.6 Quality Control 
To ensure data accuracy and reproducibility, the following quality control (QC) procedures will 
be implemented: 
(1) Questionnaire QC: ①Use of validated and standardized instruments: WURSS-24, TNSS, 
and RQLQ (Chinese versions). ②All investigators will be trained in standardized administration, 
scoring, and interview techniques. ③Face-to-face completion or guided interviews will be used. 
④All completed questionnaires will be double-checked within 24 hours by a second investigator 
to identify missing or inconsistent entries. Corrections will be made by contacting the relevant 
participant. 
(2) Blood Samples: ①Fasting blood draws scheduled between 8:00–10:00 AM with prior 
notice and scheduling. ②Unique ID codes will be assigned to all samples, matched to participant 
IDs. ③Blood will be drawn by certified nurses using standard vacuum tubes: 5 mL in coagulation 
tubes and 5 mL in EDTA tubes. ④Plasma/serum will be aliquoted and stored at −80°C. Dry ice will 
be used for cold chain transport. 
(3) Fecal Samples: ① Sterile collection kits with stabilization solution will be used. ② 
Samples will be delivered to −80°C storage within 4 hours or immediately stored on site. ③ Batch 
testing will be conducted to minimize inter-assay variability. ④ Sample coding and time-point 
tracking will be used for consistency. 
(4) Data Entry: ① Double data entry will be performed in EpiData by two independent 
investigators. ② Logic checks will be applied to prevent entry errors. ③ Weekly backups will be 
maintained on encrypted servers and external drives. ④ Final datasets will be locked prior to 
statistical analysis and archived for audit 

(5) Statistical Analysis: ① All analyses will be conducted using SAS software (version 9.4 or 
higher). ② Predefined variable libraries, missing data protocols, and sensitivity analyses will be 
applied. ③ All key results (e.g., effect sizes, p-values) will be double-verified by two statisticians. 
④ The final analysis report will be prepared in accordance with CONSORT guidelines. 
4.7 Management Policies 
(1) Intervention Product Management: Intervention products will be centrally procured and 
labeled. Distribution will be logged with batch numbers, participant IDs, and intake schedules. 
Returned and unused products will be counted to ensure traceability. 
(2) Participant Management: Participants will receive assigned IDs and follow-up schedules. 
Weekly reminders via phone or WeChat will ensure compliance. Missing ≥3 consecutive days of 
intake will be flagged as poor adherence. Reasons for withdrawal will be documented. 
(3) Sample Management: All blood and fecal samples will be centrifuged or frozen within 2 
hours and stored at −80°C. Samples are for this study only and will be managed in a coded and 
traceable system. 
(4) Data Management: Data will be entered into an electronic case report form (eCRF), double-
entered and validated. All data will be anonymized before analysis and retained for at least 5 years 
for audit purposes. 
4.8 Post-Trial Participant Care 
After trial completion, all participants will receive a free health follow-up, including blood 
routine tests and liver/kidney function assessments. Any abnormalities will be referred to outpatient 
care. Individual reports will be provided, and those in need will receive continued nutrition 
consultation services. 
5 Risks and Benefits of the Study 
There is no direct personal benefit to you from participating in this study. However, the data 
collected through your participation may provide valuable scientific evidence to support dietary 
recommendations regarding the use of prebiotics. 
The collection of blood samples will be performed under strict aseptic conditions by qualified 
personnel. The amount of blood drawn is minimal and is not expected to cause any harm to your 
health. However, there may be some minor risks associated with blood collection, including brief 
pain at the needle site, mild bruising, and in rare cases, lightheadedness or dizziness. 

6 Costs 
All nutritional supplements and health assessments required for the study will be provided free 
of charge by the research team. At the conclusion of the study, participants will receive a financial 
compensation as a token of appreciation for their time and cooperation. 
7 Compensation 
In the unlikely event that you experience harm or injury as a result of participating in this study, 
you will be provided with appropriate medical treatment and/or financial compensation in 
accordance with ethical and legal standards. 
8 Confidentiality of Participant Information 
All personal information collected during the study will be kept strictly confidential. For 
example, your biological samples will be labeled with a numerical code rather than your name. 
Personally identifiable information will not be disclosed to anyone outside the research team unless 
you provide written permission to do so. 
 
 

Informed Consent Form 
 
 
Informed Consent Form 
Dear Participant, 
You are invited to participate in a human intervention study conducted by the School of Public 
Health at Lanzhou University, entitled “Study of the Preventive Effects and Mechanisms of Yeast 
β-Glucan on Upper Respiratory Tract Infections”. This study has been reviewed and approved 
by the Ethics Committee of the School of Public Health, Lanzhou University, and complies with 
relevant ethical and scientific research standards. This informed consent form provides you with 
key information to help you decide whether to participate. Please read it carefully. If you have any 
questions, feel free to ask the study investigator. 
Purpose of the Study 
Upper respiratory tract infections (URTIs) are acute mucosal infections caused by pathogenic 
invasion of the respiratory mucosa, leading to disruption of the mucosal barrier, immune system 
activation, and inflammation. Clinical symptoms include nasal congestion, rhinorrhea, sore throat, 
cough, and hoarseness. Although URTIs are typically self-limiting, their high incidence, recurrence, 
and transmissibility—especially in dense environments such as schools and workplaces—make 
them a significant public health concern. Allergic rhinitis (AR) is a chronic upper airway 
inflammatory disease mediated by immunoglobulin E (IgE). Its classic symptoms include nasal 
itching, sneezing, clear nasal discharge, and congestion. AR patients are more susceptible to 
recurrent URTIs due to persistent inflammation of the nasal mucosa, impaired epithelial barrier, 
decreased ciliary function, and reduced local secretory IgA (sIgA) production. Moreover, AR often 
coincides seasonally with peak URTI incidence, increasing the overall burden of illness. Therefore, 
individuals with AR are considered a high-risk population for URTIs and are ideal subjects for 
evaluating preventive interventions. 
Prebiotics are substrates selectively utilized by host microorganisms that confer health benefits, 
typically by modulating gut microbiota composition and/or activity. However, research on the role 

of prebiotics in URTI prevention remains limited. Yeast β-glucan, a natural polysaccharide and 
commonly used prebiotic, has demonstrated multiple bioactivities, including immunomodulatory, 
anti-inflammatory, and gut microbiota-regulating effects. Studies suggest that yeast β-glucan can 
enhance immunity and reduce the duration and severity of cold and flu symptoms in healthy adults. 
However, its effects in AR populations remain uninvestigated. 
This study aims to conduct a randomized, double-blind, placebo-controlled trial among 
university students with persistent AR symptoms to assess the preventive effect of yeast β-glucan 
against URTIs and to explore its potential mechanisms. The results are expected to provide scientific 
evidence for the use of postbiotics in high-risk populations for URTIs. 
Study Procedures 
If you agree to participate, you will be assigned a participant ID and randomly allocated to 
either the yeast β-glucan group or the control group. The total study duration is 15 weeks, including 
a 1-week run-in period, a 12-week intervention period, and a 2-week follow-up period. During the 
intervention, participants in the yeast β-glucan group will take two capsules daily after meals, while 
the control group will take two placebo capsules with identical appearance and packaging. At 
baseline and Week 12, you will complete nutritional and physical activity assessments, undergo 
physical examinations, and provide biological samples (blood and stool). Two weeks after the 
intervention, you will complete a questionnaire to track the incidence of URTIs. Blood samples (10 
mL) will be drawn by trained nurses via venipuncture. Stool samples will be self-collected according 
to researcher instructions and handed over to the study team. All biological samples will be used 
exclusively for this study. 
Potential Benefits 
There are no direct benefits to you. However, you will receive free health assessments and 
intervention products, and your participation may help advance scientific knowledge on the 
prevention of URTIs and related diseases. 
Risks and Discomforts 
Blood sample collection will be performed under sterile conditions. Risks are minimal 
and may include slight pain, local bruising, or mild dizziness. 

Confidentiality 
All personal data and information collected during the study will be kept strictly 
confidential. Your samples and records will be labeled using numeric codes instead of your 
name. Personally identifiable information will not be shared outside the study team without 
your consent. 
Costs 
Yeast β-glucan supplements and health assessments will be provided free of charge. After 
the trial, the control group will also receive a free 12-week supply of the intervention product. 
Participants will receive a monetary compensation upon study completion. 
Compensation 
If you suffer injury or harm as a result of participating in this study, you will be entitled to free 
medical care and/or appropriate compensation. 
Voluntary Participation and Right to Withdraw 
Participation in this study is completely voluntary. You have the right to access 
information about the study at any time and may choose to withdraw at any point without 
providing a reason. Withdrawing from the study will not affect your access to medical services. 
If continuing participation poses a risk to your health, the investigator may decide to 
withdraw you from the study. 
During your participation, we ask that you: 
• Follow all study-related instructions. 
• Respond truthfully to questions from the investigators. 
• Inform the investigator of any discomfort or adverse symptoms. 
• Avoid prohibited medications or substances. 
• Provide accurate medical history and health information. 
• Inform us of any recent or ongoing participation in other studies. 
If you fail to follow the study protocol or experience study-related complications, the 
investigator may terminate your participation. 
 

Contact Information 
If you have questions about the study, experience discomfort or injury, or have concerns about 
your rights as a participant, please contact: [Professor/Dr. ] – Phone: [****] 
Consent Signature 
I have read and understood the content of this informed consent form. The investigator 
[Signature] has explained to me the study’s purpose, procedures, risks, and benefits in detail. My 
questions have been answered to my satisfaction. I voluntarily agree to participate in this study. 
 
 
Participant Signature: ______________   Date: _____ / _____ / _____ 
Investigator Signature:______________  Date: _____ / _____ / _____ 
Investigator Contact Number: _________________