Gut feeling: probiotic may ease stress and anxiety
NCT ID NCT07216729
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study tested whether a daily probiotic supplement (Lactobacillus reuteri) could lower stress, anxiety, and depressive symptoms in 150 adults aged 18-45 who reported feeling stressed. Participants took either the probiotic or a placebo for several weeks and completed surveys about their mood. The goal was to see if the probiotic helped them feel less stressed in the moment and over time.
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Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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150 people
The number who actually took part.
- Started
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Feb 2023
- Finished
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Jun 2024
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 45 years
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * 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 Exclusion Criteria: * 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
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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University of Colorado Boulder, Muenzinger Psychology Building
Boulder, Colorado, 80309, United States
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