Study of the Effects and Mechanisms of Yeast Postbiotics on Persistent Allergic Rhinitis Symptoms
Phase: NA
Conditions: Allergic Rhinitis
Sponsor: LanZhou University

 
 
 
 
 
 
 
Study of the Effects and Mechanisms of 
Yeast Postbiotics on Persistent Allergic 
Rhinitis Symptoms 
 
 
 
 
 
 
 
 
2025.6.10 
 
 

Study Protocol and Statistical Analysis Plan: 
 
Study of the Effects and Mechanisms of Yeast Postbiotics on 
Persistent Allergic Rhinitis Symptoms 
1 Background 
Allergic rhinitis (AR) is a chronic, non-infectious inflammatory disease of the nasal mucosa 
mediated by immunoglobulin E (IgE) in atopic individuals following exposure to allergens. Its 
typical clinical manifestations include paroxysmal sneezing, watery rhinorrhea, nasal itching, and 
nasal congestion, often accompanied by itchy eyes, tearing, sleep disturbances, and reduced quality 
of life. AR is one of the most common chronic nasal conditions worldwide, affecting approximately 
10%–20% of the global population, and has been recognized by the World Health Organization as 
a major public health concern. In China, the first nationwide epidemiological survey of adult AR 
was conducted in 2005. A follow-up telephone-based survey in 18 major cities in 2011 revealed that 
the self-reported prevalence of adult AR had increased from 11.1% to 17.6%, indicating a rising 
trend and increasing societal burden. Current standard treatments for AR primarily include 
antihistamines, intranasal corticosteroids, and allergen-specific immunotherapy. While these can 
alleviate symptoms, they often show variable efficacy between individuals, have high relapse rates, 
and suffer from poor long-term adherence, making it difficult to achieve sustained disease control. 
Therefore, there is an urgent need to explore safe, effective, and mechanistically clear 
interventions—especially for early prevention and control of AR. 
The human gut harbors trillions of microorganisms, which play a critical role in maintaining 
overall health. At different stages of life, both the composition of the gut microbiota and its 
interactions with the host significantly influence physiological function and health status. 
Accumulating evidence from both human and animal studies suggests a potential association 
between the gut microbiota and allergic diseases. Dysbiosis may be a key indicator of allergic 
conditions. Postbiotics refer to functional substances composed of inactivated microorganisms and 
their metabolites, such as short-chain fatty acids (SCFAs), and cell wall components like β-glucans 
and peptidoglycans. These components have been shown to exert immunomodulatory, antioxidant, 
and anti-inflammatory effects. Compared with probiotics, postbiotics offer advantages such as 

greater stability, no risks associated with live microorganisms, and improved production 
controllability. Recent studies have demonstrated that β-glucans derived from yeast-based 
postbiotics may help regulate the Th1/Th2 balance, downregulate IL-4 and IgE expression, and 
enhance Treg cell function, thus alleviating inflammation in allergic disease models such as asthma 
and food allergies. 
However, clinical research on postbiotic interventions specifically targeting AR remains 
limited. One 12-week randomized controlled trial found that oral administration of yeast 
fermentation products significantly reduced nasal congestion (P=0.04) and rhinorrhea (P=0.005), 
suggesting potential therapeutic benefits. Given the overlap in immunomodulatory mechanisms 
between postbiotics and probiotics, postbiotics may theoretically improve AR symptoms, reduce 
recurrence rates, and enhance upper respiratory mucosal defenses through multiple pathways, 
particularly the gut microbiota–immune axis. 
Based on this background, this study aims to conduct a randomized, double-blind, placebo-
controlled intervention trial among university students with persistent AR symptoms to evaluate the 
effects of yeast postbiotics on AR symptoms and related immune and microbial indicators. The goal 
is to provide scientific evidence supporting the use of postbiotics in the prevention and management 
of allergic diseases. 
2 Objectives 
(1) To evaluate the effects of yeast postbiotics on improving symptoms of persistent AR. 
(2) To explore the potential mechanisms by which yeast postbiotics alleviate persistent AR 
symptoms through modulation of the gut microbiota. 
3 Design and Methods 
3.1 Participants 
This study aims to recruit current students at Lanzhou University who have been diagnosed 
with persistent AR or who present persistent AR-like symptoms as research subjects 
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) 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 is a randomized, double-blind, placebo-controlled human intervention trial. All enrolled 
participants will be stratified based on sex and AR diagnosis status, and then randomly assigned to 
either the yeast postbiotics group or the control group. During the intervention period, participants 
in the postbiotics group will take two capsules of yeast postbiotics daily after meals, while the 
control group will receive two matching placebo capsules. The total duration of the trial is 15 weeks, 
including 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 receive yeast postbiotic capsules, each containing 
250 mg of yeast postbiotics, maltodextrin, and a small amount of silicon dioxide. The placebo group 

will receive capsules identical in form, taste, appearance, and packaging, composed only of 
maltodextrin and silicon dioxide. All participants will take two capsules once daily with warm water 
after meals. 
3.4 Safety Assessment of Yeast Postbiotics 
The yeast postbiotics used in this study are provided by Angel Yeast Co., Ltd., and have passed 
a series of toxicological safety assessments, including: acute oral toxicity test, bacterial reverse 
mutation test (Ames test), mammalian erythrocyte micronucleus test, Chromosomal aberration test 
in mouse spermatogonia or spermatocytes, and 28-day repeated oral toxicity test. All results 
confirmed no toxicity or mutagenic risks at the given dosages. Yeast and its derivatives have a long 
history of safe use in food fermentation and nutritional supplementation, with their safety verified 
by both population consumption and regulatory evaluations. Therefore, the intervention is 
considered highly safe. Nevertheless, adverse events (AEs) will be monitored continuously 
throughout the study, and any serious adverse events will be reported and managed according to 
ethical requirements. 
3.5 Randomization, Blinding, and Unblinding 
Stratified randomization will be performed using the blockrand package in R, with fixed block 
sizes and two stratification factors: sex (male/female) and confirmed AR diagnosis (yes/no, based 
on self-reported clinical history). Participants will be randomly assigned in a 1:1 ratio to the 
intervention or control group within each stratum. The randomization sequence will be sealed in 
opaque envelopes for allocation concealment. After signing informed consent and passing the 
screening, participants will be assigned ID codes and allocated accordingly. 
Double-blinding will be applied to both participants and investigators. Only the study designer 
will have access to the group allocation. Intervention products and sample labels will be coded to 
prevent unblinding. If a participant experiences serious adverse effects related to the intervention, 
unblinding will be performed and the participant withdrawn. 
3.6 Sample Size Estimation and Statistical Analysis 
The sample size was calculated using the standard formula for randomized controlled trials： 
𝑁= 2(𝑍1−𝛼+ 𝑍1−𝛽)2𝜎2
𝑑2
 
Based on the Total Nasal Symptom Score (TNSS) as the primary outcome and parameters α = 

0.05, β = 0.1, σ = 1.70, and d = 1.30, the calculated sample size is 36 per group (72 total). 
Considering a 10% dropout rate, at least 80 participants will be enrolled. 
Statistical analysis will be conducted using SAS 9.4. Continuous variables will be expressed 
as mean ± standard deviation (SD); ordinal variables as rates. group comparisons will use:t-test or 
Kruskal-Wallis test for continuous variables and Chi-square test or Fisher's exact test for categorical 
variables. A P-value < 0.05 will be considered statistically significant. 
For repeated measures across multiple time points (Weeks 0, 2, 4, and 12), such as TNSS and 
inflammatory markers, linear mixed-effects models (LMMs) will be constructed to assess the effects 
of time, group, and their interaction. 
3.7 Outcome Measures 
3.7.1 Primary Outcome 
TNSS: Evaluates four nasal symptoms—itching, sneezing, runny nose, and congestion—each 
scored 0 to 3. Total score: 0–12, with higher scores indicating greater severity. 
3.7.2 Secondary Outcomes 
(1) Visual Analogue Scale (VAS): A 0–10 cm line, where 0 = no symptoms and 10 = worst 
symptoms. Used for assessing subjective severity and frequency of AR symptoms. 
(2) Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ): 28 items across 7 domains 
(daily activity, sleep, nasal/ocular symptoms, emotional status). Each scored 0–6. Higher scores 
indicate lower quality of life. 
(3) Serum Specific IgE (sIgE): Detected using FEIA (e.g., ImmunoCAP). Levels ≥0.35 kU/L 
indicate sensitization. 
(4) Secretory IgA (sIgA): Measured in fecal and saliva samples via ELISA to reflect mucosal 
immunity. 
(5) Inflammatory Cytokines: IFN-γ, IL-4, IL-10, IL-6, TNF-α measured by high-sensitivity 
ELISA. IFN-γ/IL-4 ratio used to infer Th1/Th2 balance. 
(6) Gut Microbiota Composition: Assessed via 16S rRNA gene sequencing from fecal samples 
to evaluate α/β diversity and dominant genera. 
(7) Serum Biochemical Indicators: CRP, ALT/AST, BUN/Cr measured by automated 
biochemistry analyzers to monitor systemic inflammation, liver, and kidney function. 

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. IRB25041501). 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 80 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, VAS, and dietary 
intake assessment. 
(2) Anthropometric Measurements: Height, weight, body fat percentage. 
(3) Blood Sampling: Used to measure immune indicators, inflammatory cytokines, and sIgE. 
(4) Saliva Sampling: Used to measure secretory sIgA levels. 
(5) Fecal Sampling: Used to measure secretory sIgA levels and perform 16S rRNA sequencing 
analysis of the gut microbiota. 
4.3 Randomization 
This study adopts a stratified randomization method, in which participants are randomly 
assigned to either the yeast postbiotics group or the placebo group. Stratification factors include:(1) 
Sex (male/female); (2) Diagnosis of AR (yes/no, based on self-reported clinical history), ensuring 
balance and comparability between the two groups. 
4.4 Intervention 
Participants in the yeast postbiotics group will take two capsules of yeast postbiotics daily. 
Participants in the placebo group will take two placebo capsules daily, which are identical in 
formulation, taste, appearance, and packaging to the intervention capsules but only contain 
maltodextrin and a small amount of silicon dioxide. After group assignment, each participant will 
receive one bottle of the intervention product (90 capsules/bottle). At the 4-week follow-up, 
remaining capsules will be counted and a second bottle (90 capsules) will be distributed. Throughout 
the study period, all participants are instructed to avoid any additional intake of probiotics, 
prebiotics, or synbiotics, and to maintain their usual dietary and physical activity habits. To ensure 
ethical fairness, participants in the placebo group will be offered yeast postbiotic capsules after the 
intervention as post-trial nutritional support. 

4.5 Follow-up 
4.5.1 Follow-up Components: 
(1) Scheduled follow-ups: All participants will undergo four scheduled follow-up visits at week 
0, week 2, week 4, and week 12 of the intervention. The visits at week 0, week 4, and week 12 
include: ① Questionnaire assessments: TNSS (Total Nasal Symptom Score), VAS (Visual Analog 
Scale), RQLQ (Rhinoconjunctivitis Quality of Life Questionnaire), and dietary survey. ② Physical 
measurements: height, weight, body fat percentage. ③ Sample collection: blood, urine, saliva, and 
fecal samples. ④ Adverse events: All reported adverse events will be verified and graded by the 
study investigator. 
At week 2, only saliva samples will be collected. 
(2) Daily follow-up: After randomization, all participants will be assigned to three management 
groups, each overseen by two investigators for daily follow-up. Starting from the first day of 
intervention, participants must complete an electronic questionnaire daily to record:① TNSS 
score.② Medication adherence (number of capsules taken, dosage, and time of intake).③ Any 
adverse events.All participants will receive training before the trial on how to complete the 
questionnaire accurately to ensure consistent and reliable scoring. 
(3) Adherence Monitoring: Each participant is required to take daily photos of their capsule 
intake and upload them to the study system or designated group. During each scheduled follow-up, 
investigators will count remaining capsules to calculate the compliance rate. If any participant 
misses doses or stops the intervention, investigators will conduct follow-up to determine whether 
the participant should be withdrawn from the study. 
4.5.2 Data Collection Procedures: 
(1) Basic Information Survey, Physical Measurements, and Sample Collection: All participants 
will undergo physical measurements, sample collection, and basic information surveys in the 
morning under fasting conditions before the intervention, and at weeks 4 and 12 of the intervention. 
① Basic Information Survey: A structured questionnaire will be administered face-to-face to 
collect basic demographic and lifestyle data, including name, gender, age, physical activity, smoking 
and alcohol consumption, medical history, family history, allergen exposure, and allergy-related 
history (such as AR-related conditions). 
② Physical Measurements: Standardized procedures will be used to measure height, weight, 

waist circumference, hip circumference, and blood pressure. Body Mass Index (BMI) will be 
calculated as weight (kg) divided by height squared (m²), with values recorded to two decimal places. 
③ Sample Collection: 
Blood samples: 10 mL of venous blood will be collected by a qualified nurse. Participants must 
fast for 10–12 hours before blood collection. After collection, samples will stand at room 
temperature for 3–5 minutes, followed by centrifugation at 3000 rpm for 10 minutes. The plasma 
will be separated and transferred into labeled EP tubes and stored at −80°C for future analysis. 
Fecal samples: Participants will use sterile cryotubes to collect stool from the central portion 
to avoid contamination with urine or diarrhea. Samples must be delivered to −80°C storage within 
1 hour. 
Midstream urine samples: Participants will collect midstream urine in a clean container, then 
transfer it into EP tubes and store it at −80°C. 
Saliva samples: After rinsing the mouth with water and resting for 5–10 minutes, participants 
will discard the initial saliva. The subsequent saliva will be collected in a clean cup and transferred 
into EP tubes, then frozen at −80°C. 
(2) Dietary Intake: A 3-day consecutive dietary recall will be conducted before the intervention, 
and again at weeks 4 and 12. Participants will be required to record their complete dietary intake 
over three consecutive days (including two weekdays and one weekend day), covering all foods and 
beverages consumed (e.g., breakfast, lunch, dinner, fruits, snacks, and additional meals). Detailed 
entries must include the food name, ingredients, preparation methods, and portion sizes. For 
packaged snacks and drinks, the brand name should also be indicated. Prior to data collection, 
participants will receive standardized training, including a food atlas to assist with accurate portion 
size estimation. Investigators will collect and review the completed dietary records daily. If any 
information is missing or unclear, researchers will promptly contact the participant for clarification 
or supplementation to ensure the accuracy and completeness of the dietary survey. 
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: TNSS, VAS 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 
Participation in this study does not offer you direct benefits, but we hope that the information 
obtained from your participation will provide important theoretical evidence for developing 
appropriate dietary recommendations for postbiotics. 
The collection of your blood samples will be performed under strict aseptic conditions, and 
drawing a small amount of blood will not harm your health. However, there may be minor risks 
associated with sample collection, such as brief pain, localized bruising, or mild dizziness in a small 
number of individuals. 
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 Effects and Mechanisms of Yeast Postbiotics 
on Persistent Allergic Rhinitis Symptoms”. 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 
Allergic rhinitis (AR) is a chronic, non-infectious inflammatory disease of the nasal mucosa 
mediated by immunoglobulin E (IgE) in atopic individuals after exposure to allergens. Typical 
clinical symptoms include paroxysmal sneezing, clear nasal discharge, nasal itching, and nasal 
congestion, often accompanied by itchy eyes, tearing, sleep disturbances, and reduced quality of 
life. AR is one of the most common chronic nasal diseases, affecting approximately 10%–20% of 
the global population, and has been identified by the World Health Organization as a significant 
public health issue. 
Postbiotics are functional substances composed of inactivated microorganisms and their 
metabolic products, such as short-chain fatty acids and cell wall components (e.g., β-glucan, 
peptidoglycan). They possess various biological activities, including immunomodulatory, 
antioxidant, and anti-inflammatory effects. Compared with probiotics, postbiotics offer advantages 
such as greater stability, no risks associated with live bacteria, and better controllability in 
production. Previous studies have shown that β-glucan derived from yeast-based postbiotics can 
regulate the Th1/Th2 balance, downregulate IL-4 and IgE expression, and enhance Treg cell 

function. These effects have demonstrated the potential to alleviate inflammatory responses in 
allergic diseases such as asthma and food allergies in animal models. However, research on 
postbiotic interventions for AR remains limited. 
Based on this background, this study aims to conduct a randomized, double-blind, placebo-
controlled intervention trial among college students with persistent AR symptoms to evaluate the 
effects of yeast postbiotics on AR symptoms and related immunological and microbiota indicators. 
The goal is to provide scientific evidence supporting the use of postbiotics in the prevention and 
treatment of allergic diseases. 
Study Procedures 
If you agree to participate in this study, you will be assigned a participant number and randomly 
allocated to either the yeast postbiotic group or the control group. The study will last for 15 weeks, 
consisting of a 1-week run-in period, a 12-week intervention period, and a 2-week follow-up period. 
During the intervention, participants in the intervention group will take two yeast postbiotic capsules 
daily after meals, while the control group will take an equivalent amount of placebo. At baseline, 
week 4, and week 12, you will undergo nutritional surveys, physical activity assessments, physical 
examinations, and collection of biological samples (blood, urine, saliva, and feces). Saliva samples 
will also be collected at week 2 of the intervention. Two weeks after the intervention ends, a 
questionnaire will be used to follow up on changes in AR symptoms. A trained nurse will collect 10 
mL of venous blood from your arm. Urine, saliva, and stool samples are to be self-collected 
according to the researchers' instructions and submitted promptly to research staff. Your samples 
will be used solely for this study. 
Potential Benefits 
There are no direct benefits to you from participating in this study. However, you will receive 
free health assessments and intervention products. Your participation will help researchers provide 
scientific evidence for nutritional interventions in AR and similar 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 Postbiotics 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: _________________