The Effects of Probiotic Supplementation on State and Trait Stress, Anxiety, and Depression Symptoms in Stressed Adults

NCT07216729 | Completed

• 1 other identifier: 22-0234
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this randomized controlled trial is to learn if supplementation with the probiotic Lactobacillus reuteri DSM 17938 can reduce levels of trait and state perceived stress, anxiety, and depressive symptoms compared to a placebo in a population of stressed adults ages 18-45. This study also investigates several evidence-based moderators of treatment effects, evaluates whether the probiotic caused side effects, and evaluates whether effects endured at 1-month post-supplementation.

Conditions

Anxiety Symptoms; Perceived Stress; Depressive Symptoms

Keywords

Lactobacillus reuteri DSM 17938; Perceived stress; Anxiety; Depression; Probiotic; Randomized controlled trial

Outcome Measures

Primary Outcomes (2)

• Change from baseline in mean trait perceived stress as assessed by PSS-10

  Perceived stress scale-10 (PSS-10) administered via REDCap. Possible score range of 0 to 40, with 0-13 considered low stress, 14-26 moderate stress, and 27-40 high stress.

  Baseline and the end of treatment at 46 days

• State perceived stress as assessed by adapted PSS-4 using ecological momentary assessment

  Perceived stress scale-4 (PSS-4) administered via REDCap and adapted for state measurement. The investigators adapted this measure for state stress by asking participants to rate the intensity of perceived stress they were experiencing in the moment, as opposed to the frequency with which they experienced perceived stress over the past month. Possible score range of 0 to 16, with higher scores indicating higher levels of state stress.

  Five times per day (hourly, 12-7pm, sent via text with a 15 minute response window) during the last 5 days of supplementation, days 42 to 46, when the investigators expect participants to have reached maximum benefit

Secondary Outcomes (4)

• Change from baseline in mean trait anxiety symptoms as assessed by GAD-7

  Baseline and the end of treatment at 46 days

• State anxiety symptoms as assessed with the SUDS using ecological momentary assessment

  Five times per day (hourly, 12-7pm, sent via text with a 15 minute response window) during the last 5 days of supplementation, days 42 to 46, when the investigators expect participants to have reached maximum benefit

• Change from baseline in mean trait depressive symptoms as assessed by the PHQ-8

  Baseline and the end of treatment at 46 days

• State depressive symptoms as assessed by SUDS using ecological momentary assessment

  Five times per day (hourly, 12-7pm, sent via text with a 15 minute response window) during the last 5 days of supplementation, days 42 to 46, when the investigators expect participants to have reached maximum benefit

Other Outcomes (1)

• Side effects as assessed on the final day of supplementation using the GASE

  End of treatment at day 46

Study Arms (2)

Probiotic

EXPERIMENTAL

5 drops daily (100 million colony-forming units) for 46 days of Lactobacillus reuteri DSM 17938 in sunflower oil, medium chain triglyceride oil, and silicon dioxide.

Dietary Supplement: Lactobacillus reuteri DSM 17938

Placebo

PLACEBO COMPARATOR

5 drops daily for 46 days of a placebo consisting of the inactive ingredients from the probiotic supplement, specifically sunflower oil, medium chain triglyceride oil, and silicon dioxide.

Other: Placebo

Interventions

Lactobacillus reuteri DSM 17938 DIETARY_SUPPLEMENT

5 drops (100 million CFUs) daily for 46 days of L. reuteri DSM 17938 in sunflower oil, medium chain triglyceride oil, and silicon dioxide.

Probiotic

Placebo OTHER

5 drops daily for 46 days of placebo consisting of inactive ingredients from probiotic supplement, specifically sunflower oil, medium chain triglyceride oil, and silicon dioxide.

Placebo

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• age 18 - 45
• scoring 14+ on the perceived stress scale-10 indicating medium stress or higher
• ability to provide informed consent
• willingness not to take probiotic supplements (pills, tablets, oils, etc.) other than the product provided in the clinical study until all study procedures are completed
• own a smartphone and are willing to receive study materials and complete study procedures by text

You may not qualify if:

• a history of gastrointestinal discomfort or surgery, urinary incontinence, cancer, toxic shock syndrome, frequent diarrhea, vital signs outside of the acceptable range (i.e., blood pressure \>160/100, oral temperature \>100°F, pulse \>100), heart disease, heart attack, lung/respiratory disease, any pulmonary, cardiovascular, gastrointestinal, hepatic or renal functional abnormality (i.e. a medical diagnosis related to lungs, heart, stomach/intestines, liver, or kidneys), HIV, Hepatitis B, Hepatitis C, bipolar disorder, psychosis, or confirmed or suspected immunosuppression or immunodeficiency
• current (past month) alcohol or substance abuse or dependence (score of 2+ on the UNCOPE)
• consistent (e.g., 5x/week or greater) probiotic supplementation within the last month, including probiotic food products such as yogurt
• receiving antibiotics within the last month
• receiving medications that interfere with gut motility (opiates, loperamide, stool softeners)
• use of systemic antibiotics, antifungals, antivirals, or antiparasitics (intravenous, intramuscular, or oral)
• use of oral, intravenous, intramuscular, nasal or inhaled corticosteroids
• use of cytokines or cytokine inhibitors
• use of methotrexate or immunosuppressive cytotoxic agents
• receiving immunosuppressive drugs/medications or treatment including antineoplastic therapy, post-transplantation immunosuppressive therapy, and/or radiation therapy
• participation in conflicting interventional research protocol
• unstable dietary history as defined by major changes in diet during the previous month, where the subject has eliminated or significantly increased a major food group in their diet
• female who is pregnant or lactating or reports expecting to get pregnant during the course of the study
• currently involved in the criminal justice system as a prisoner or ward of the state

Sponsors & Collaborators

• University of Colorado, Boulder: lead

Study Sites (1)

University of Colorado Boulder, Muenzinger Psychology Building

Boulder, Colorado, 80309, United States

Location

Related Links

• Prior pre-registration on Open Science Framework, initially submitted prior to starting data collection

MeSH Terms

Conditions

Anxiety Disorders; Depression

Condition Hierarchy (Ancestors)

Mental Disorders; Behavioral Symptoms; Behavior

Study Officials

• Lauren B Finkelstein, MA

  University of Colorado, Boulder

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: SUPPORTIVE CARE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: October 10, 2025
• First Posted: October 15, 2025
• Study Start: February 20, 2023
• Primary Completion: May 6, 2024
• Study Completion: June 1, 2024
• Last Updated: November 18, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ANALYTIC CODE
• Time Frame: Beginning late summer/early fall of 2024 with no end date
• Access Criteria: Faculty advisor who oversaw the initial trial is supervising another graduate student to use the data to address research questions outlined in the IRB-approved protocol, in addition to some secondary analyses.

Locations

US (1)