An interventional study of Probiotics and placebo in Cognitive Ability, General, Immune System Function and Emotions, sponsored by University of Utah. Completed at 2 sites in United States. Open to participants aged 12 Years to 20 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-04.
Sponsored by University of Utah · Not applicable, Interventional, and Other
Stress is a normal human reaction to changes surrounding our reality, resulting in physical, emotional, and intellectual responses. Children and adolescents often experience high levels of stress. Age and gender may affect a child's ability to manage stress. Children and adolescents experiencing stress could be at an increased risk of poor cognitive, social, and emotional functioning. Probiotics are living microorganisms that could positively affect microbiota, support functions of numerous organs and systems, and overall human health. Most probiotics belong to the Lactobacillus genus. Probiotics can potentially support mental health, psychological function, and immune defenses.
The purpose of this exploratory clinical trial is to investigate whether supplementation of the diets of adolescents experiencing moderate stress with the probiotic dietary supplement a blend of two probiotic Lactobacillus plantarum and one Lactobacillus brevis strains will support their emotions (e.g., psychological well-being, social relationship, stress levels, and self-efficacy), cognitive (e.g., attention, episodic and working memory) and immune functions (e.g., salivary IgA and salivary cytokine productions). This study is intended only to evaluate the dietary supplement's effect on the body's structure or function. Our investigation is not intended to mitigate, cure, treat, or prevent disease.
Children and adolescents often experience high levels of stress. Age and gender may affect the ability of a child to manage stress. Children and adolescents experiencing stress could be at an increased risk of poor cognitive, social, and emotional functioning, and may have altered immune responses due to stress.
Probiotics are living microorganisms that could positively affect microbiota, support functions of numerous organs and systems, and overall human health. Most probiotics belong to the Lactobacillus genus. It has been suggested that probiotics potentially can support mental health, psychological function, and immune defenses. Recent studies confirmed that the use of pre- and probiotics improves the psychological scores of people predisposed to mood disorders. A supplementation of the diet of healthy volunteers with a probiotic for four weeks resulted in a significant reduction of subjects' rumination and aggressive thoughts. Lactobacillus plantarum DR7 reduces signs of stress and improves immune functions in adults. Consumption of this probiotic for 12 weeks reduced signs of stress and improved the psychological scores of participants. The levels of inflammatory cytokines are higher in people with anxiety. The use of Lactobacillus plantarum DR7 reduced levels of inflammatory cytokines (e.g., IFNgamma).
The purpose of this exploratory clinical trial is to investigate whether supplementation of the diets of adolescents experiencing moderate stress with the probiotic dietary supplement a blend of two Lactobacillus plantarum and one Lactobacillus brevis probiotic strains will support participants emotions (e.g., psychological well-being, social relationship, stress levels, and self-efficacy), cognitive (e.g., attention, episodic and working memory) and immune functions (e.g., salivary IgA and salivary cytokine productions). This study is intended only to evaluate the dietary supplement's effect on the body's structure or function. Our investigation is not intended to mitigate, cure, treat, or prevent disease.
The study will be an exploratory single-blind, randomized clinical trial of a dietary supplement containing 2 billion CFU of a probiotic strains: two Lactobacillus plantarum and one Lactobacillus brevis probiotic strains. Stains are present in the mixture at a ratio of 2:1:1. All strains are currently used as dietary supplements in the United States.
Participants for this trial will be selected based on the following criteria: participants age 12-20 years old, BMI percentile >5% and \<97% with moderate stress levels (Perceived Stress Scale (PPS) score 14-26), receiving or not receiving cognitive behavioral therapy, and not on selective serotonin reuptake inhibitors (SSRIs). Investigators planned to enroll 120 participants, with 60 participants in the dietary supplement (Probiotics) arm. The probiotics arm will receive caps with the probiotic blend, and control participants will receive caps containing a placebo for the same period. Participants will be asked to consume the caps with dinner meals for 12 consecutive weeks. If the probiotic was not taken during dinner, then it should be taken within 2 hours after dinner or with the next meal.
The investigators have used the NIH Toolbox for Assessment of Neurological and Behavioral Function, which has been designed for scientists interested in evaluating the emotional and cognitive functions of clinical study participants. NIH Toolbox was validated across the entire age range.
The Investigators used the following NIH Toolbox domains to assess participants' progress:
Biomarkers of immune function were investigated: salivary cytokine levels IL1beta, IL6, IL8, IFNgamma, and TNFα, and IL10, and immunoglobulin - secretory IgA.
4. Salivary AM and PM cortisol levels were measured All biomarkers were measured at baseline, 8 weeks, and 12 weeks of probiotics/placebo use by participants.
University of Utah is the lead sponsor of 969 studies on the registry; 178 are open to participants now.
Of its 107 completed or terminated interventional studies of FDA-regulated products, 62 (58%) have results posted.
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Exclusion Criteria:
Participants received the probiotics blend containing two Lactobacillus plantarum and one Lactobacillus brevis strains for 12 weeks. The probiotic blend contained 2 billion CFU bacteria. Stains are present in the mixture at a ratio of 2:1:1. Participants were taking them daily with meals, (preferably with a dinner meal) for 12 consecutive weeks. If the probiotic was not taken during dinner, it should be taken within 2 hours after dinner or with the next meal
Dietary Supplement: Probiotics
The participants started taking placebo capsules the day after the first visit, after collecting the AM saliva sample, and continued taking them daily (preferably with a dinner meal) for 12 consecutive weeks. If the capsule was not taken during dinner, it should be taken within 2 hours after dinner or with the next meal
Dietary Supplement: placebo
The participants started taking capsules the day after the first visit, after collecting the AM saliva sample, and continued taking them daily (preferably with a dinner meal) for 12 consecutive weeks. If the probiotic was not taken during dinner, it should be taken within 2 hours after dinner or with the next meal
The participants started taking placebo capsules the day after the first visit, after collecting the AM saliva sample, and continued taking them daily (preferably with a dinner meal) for 12 consecutive weeks. If the probiotic was not taken during dinner, it should be taken within 2 hours after dinner or with the next meal
Emotinal status and cognitive functions of participants
The NIH Toolbox was used to assess participants' emotional and cognitive functions. The Emotion Domain consisted of instruments evaluating psychological well-being, social relationships, stress, self-efficacy, and negative affect. Additionally, PROMIS CAT Emotional Support, Psychological Stress Experiences, and Sleep Disturbance tests were administered. The Cognition Domain test consisted of attention, episodic and working memories, language, and processing speed.
Time frame: From enrollment (week 0), 8 weeks and 12 weeks (end of study)
Changes in the immune functions of participants
Biomarkers of immune function were analyzed. 1. Salivary cytokine levels: IL1beta, IL6, IL8, IFNgamma, and TNFα, and Th2 (IL10) cytokines, 2. Salivary immunoglobulin sIgA. Collected samples were stored in a -80°C freezer until shipped for analysis to Salimetrics. Saliva samples were analyzed in duplicates by Salimetrics.
Time frame: From enrollment (week 0), 8 weeks and 12 weeks (end of study)
Evaluation of AM and PM cortisol levels
Salivary samples for cortisol analysis were collected by participants 1-2 days before the in-person appointment and stored in the household freezers. AM samples were collected before 8 AM, and PM samples were collected 2 hours before bedtime. Levels of cortisol were analyzed by Salimetrics
Time frame: From enrollment (week 0), 8 weeks and 12 weeks (end of study)
Plan to share: No
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