Effects of Continuous Yogurt Intake on Immunomodulatory Function and Subjective Health Status in Healthy U.S. Adults

Randomized, Double-Blind, Controlled Study on the Effects of Continuous Yogurt Intake on Immunomodulatory Function and Subjective Health Status in Healthy U.S. Adults

This study evaluates the effects of daily consumption of a yogurt on immune function and subjective health status in healthy adults in the United States. Participants are randomly assigned to receive either the active yogurt or a placebo once daily for 8 weeks. The study assesses immune function using salivary immunoglobulin A and other immune-related biomarkers. The study also evaluates cold-like symptoms, quality of life, gastrointestinal symptoms, stress, and sleep-related outcomes.

Study Overview

• Status: Not yet recruiting
• Conditions: Immune Function
• Intervention / Treatment: Dietary supplement: Yogurt drink; Dietary supplement: Acidified lactic beverage

• Study Type: Interventional
• Enrollment (Estimated): 118
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Atlantia Clinical Trials

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Be able to give written informed consent.
• Be between 18-65 years, inclusive.
• Be in general good health, as determined by the in investigator.
• Willing to consume study product daily for the duration of the study.
• Has a body mass index (BMI) ≤39.9 kg/m2
• Willing to refrain from consuming alcohol for the 24 hours prior to each study visit.
• Willing to maintain current lifestyle habits, including dietary and caffeine and alcohol intake, for the duration of the study.

Exclusion Criteria:

• Participants who are pregnant or wish to become pregnant during the study or who are lactating and/or currently breastfeeding.
• Participants currently of biological childbearing potential, but not using a continuous effective method of contraception.
• Has a history of drug and/or alcohol abuse at the time of enrolment.
• Drinks more than nationally recommended units of alcohol per day/week.
• Has milk allergy or other food allergies or other issues with foods that would preclude intake of the SP.
• Has an excessive smoking habit.
• Has any significant acute or chronic coexisting health conditions that would prevent them from fulfilling the study requirements, put the participant at risk or would confound the interpretation of the study results as judged by the investigator on the basis of medical history and laboratory test results.
• Dental or intraoral treatment.
• Visited a hospital or clinic for allergic rhinitis (pollinosis) within the past year or those who plan to take prescription drugs to treat or prevent allergic rhinitis during the study period.
• Current or recent (in the past 4 weeks) use of a medication that the investigator believes would interfere with the objectives of the study or pose a safety risk or confound the interpretation of the study results.
• Current or recent (in the past 4-weeks) use of prohibited nutritional or non-nutritional dietary supplements that the investigator believes would interfere with the objectives of the study or pose a safety risk or confound the interpretation of the study results.
• Current or recent (in the past 2 weeks) use of yogurt (other than the study product)
• Participants who have donated blood in the previous 8-weeks.
• Individuals who, in the opinion of the investigator, are considered to be poor attendees or unlikely for any reason to be able to comply with the study.
• Participants may not be participating in other clinical studies. If the participant has previously taken part in an experimental study, the Investigator must ensure sufficient time has elapsed before entry to this study to ensure the integrity of the results.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Active study product; Participants receive 120 g of the yogurt drink once daily for 8 weeks.	Dietary supplement: Yogurt drink; Participants receive 120 g of the yogurt drink once daily for 8 weeks.
Placebo Comparator: Placebo study product; Participants receive 120 g of the acidified lactic beverage once daily for 8 weeks.	Dietary supplement: Acidified lactic beverage; Participants receive 120 g of the acidified lactic beverage once daily for 8 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Salivary IgA flow rate	Saliva is collected by allowing naturally secreted saliva to passively drool into a sterile collection tube or vial without chewing or making oral movements. The time required to collect the specified volume of saliva is recorded. The salivary IgA flow rate is calculated by multiplying the salivary IgA level by the slivary flow rate.	Baseline (Week 0) and Endpoint (Week 8)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cold-like symptoms and absenteeism	The Jackson Cold Scale (self-reported) is used to assess symptom frequency, symptom severity, symptom duration, frequency of absenteeism from school/work, and duration of absenteeism from school/work. The Jackson Cold Scale (JCS) is an assessment covering the past 24 hours of eight upper respiratory tract infection (URTI) symptoms using a four-point response range (0=absent, 1=mild, 2=moderate, and 3=severe). The total score is calculated by summing the eight symptom scores (sneezing, headache, malaise, chilliness, nasal discharge, nasal obstruction, sore throat and cough). Participants will complete this questionnaire for each day during the intervention period starting Day 0	from baseline to Week 8
Salivary IgA flow rate (baseline to 4 weeks)	Saliva is collected by allowing naturally secreted saliva to passively drool into a sterile collection tube or vial without chewing or making oral movements.	Baseline (Week 0), Midpoint (Week 4)
Salivary IgA level	Saliva is collected by allowing naturally secreted saliva to passively drool into a sterile collection tube or vial without chewing or making oral movements. IgA concentration in saliva is measured using ELISA.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Expression intensity and frequency of immune cell activation markers	CD3, CD19, CD56, CD14, CD11c, CD123, CD304, CD4, CD8, CD16, CD45RO, CCR7, CD69, CD86, HLA-DR	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Concentration of Inflammatory Cytokines in Blood	GCSF, GM-CS, GRO alpha/beta/gamma, GRO alpha (CXCL1), IL-1 alpha, IL-2, IL-3, IL-5, IL-6, IL-7, IL-8 (CXCL8), IL-10, IL-13, IL-15 IFN-gamma, MCP-1 (CCL2), MCP-2 (CCL8), MCP-3 (MARC/CCL7), MIG (CXCL9), RANTES (CCL5), TGF beta 1, TNF alpha, TNF beta (TNFSF1B)	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Gastrointestinal symptoms (GSRS - total score)	The Gastrointestinal Symptom Rating Scale (GSRS) is a self-administered questionnaire used to assess the severity and frequency of gastrointestinal symptoms over the previous 7-days. The GSRS consists of a self-administered questionnaire with 15 items, which are divided into five subscales representing different symptom groups: Reflux, Abdominal Pain, Indigestion, Diarrhoea and Constipation. Each item on the GSRS is rated on a 7-point Likert scale, where 1 indicates the absence of symptoms and 7 indicates very severe symptoms. The scores for each subscale are calculated separately or can be summed for a total score, and higher scores indicate greater severity of symptoms. In this study, GSRS total score is used.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Quality of Life (SF-36 RAND - General Health and Energy/Fatigue Domain Scores)	The 36-Item Short Form Survey developed by RAND (SF-36 RAND) is a self-reported outcome measure instrument on health that is often used and well-researched. The SF-36 RAND taps eight health concepts: physical functioning, bodily pain, role limitations due to physical health problems, role limitations due to personal or emotional problems, emotional well-being, social functioning, energy/fatigue, and general health perceptions. The form asks participants to reply to questions according to how they feel in general and how they have felt over the past 4 weeks. The items use Likert-type scales, some with five or six points and others with two or three points, with scores ranging from 0 to 100. Higher scores indicate higher quality of life. In this study, two domain scores, General Health and Energy/Fatigue, are used.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
DASS-21- Stress Score	DASS-21 is a self-reported scale designed to measure the emotional states of depression, anxiety and stress over the previous 7-days. Each of the three DASS-21 scales contains 7 items, divided into subscale. The depression scale assesses dysphoria, hopelessness, devaluation of life, self-deprecation, lack of interest / involvement, anhedonia and inertia. The anxiety scale assesses autonomic arousal, skeletal muscle effects, situational anxiety, and subjective experience of anxious affect. The stress scale is sensitive to levels of chronic nonspecific arousal. It assesses difficulty relaxing, nervous arousal, and being easily upset / agitated, irritable / over-reactive and impatient. Scores for depression, anxiety and stress are calculated by summing the scores for the relevant items. The total score for stress will be assessed as part of the secondary objectives of this study.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Sleep Disturbance 8A (SD 8A)	The PROMIS Sleep Disturbance instruments assess self-reported perceptions of sleep quality, sleep depth, and restoration associated with sleep. This includes perceived difficulties and concerns with getting to sleep or staying asleep, as well as perceptions of the adequacy of and satisfaction with sleep. Sleep Disturbance does not focus on symptoms of specific sleep disorders, nor does it provide subjective estimates of sleep quantities (total amount of sleep, time to fall asleep, amount of wakefulness during sleep). The Sleep Disturbance short form is universal rather than disease specific. It assesses sleep disturbance over the past seven days. Each item is rated on a 5-point scale.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)
Sleep related impairment 8A (SRI 8A)	The PROMIS Sleep-Related Impairment focuses on self-reported perceptions of alertness, sleepiness, and tiredness during usual waking hours, and the perceived functional impairments during wakefulness associated with sleep problems or impaired alertness. Though Sleep-Related Impairment does not directly assess cognitive, effective, or performance impairment, it does measure waking alertness, sleepiness, and function within the context of overall sleep-wake function. The Sleep-Related Impairment short form is universal rather than disease-specific. It assesses sleep-related impairment over the past seven days. Each item is rated on a 5-point scale.	Baseline (Week 0), Midpoint (Week 4) and Endpoint (Week 8)

Collaborators and Investigators

• Sponsor: Meiji Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Estimated): September 14, 2026
• Primary Completion (Estimated): June 28, 2027
• Study Completion (Estimated): June 28, 2027

Study Registration Dates

• First Submitted: August 25, 2026
• First Submitted That Met QC Criteria: August 28, 2026
• First Posted (Actual): September 2, 2026

Study Record Updates

• Last Update Posted (Actual): September 2, 2026
• Last Update Submitted That Met QC Criteria: August 28, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Probiotics; Immune Function; Healthy Adults; Yogurt
• Other Study ID Numbers: AFCRO-198

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No