Probiotic Study in Alcohol Recovery
September 10, 2026 updated by: Kim-Marie Gehrke, Loughborough University
Effects of Probiotic Supplementation in Alcohol Use Disorder: A Randomised, Placebo-Controlled Pilot Trial
Alcohol Use Disorder (AUD) is a common condition that can affect physical and mental health. Current treatments do not work for everyone, and new approaches are needed.
The primary aim of this study is to assess whether taking a specific probiotic supplement (a type of "good bacteria") is a feasible approach for people with AUD - that is, whether it is practical, acceptable, and well-tolerated within this population. As a secondary aim, the study also explores whether the probiotic may help improve psychological, biological, and cognitive wellbeing.
Participants are randomly assigned to receive either a probiotic supplement or a placebo (a capsule with no active ingredients) for four weeks. Neither the participants nor the researchers know which treatment is given during the study.
The aim is to understand whether probiotics could be a feasible and helpful additional approach to support people with AUD.
Study Overview
Status
Completed
Conditions
Intervention / Treatment
Study Type
Interventional
Enrollment (Actual)
38
Phase
- Not Applicable
Contacts and Locations
This section provides the contact details for those conducting the study, and information on where this study is being conducted.
Study Locations
-
-
-
Loughborough, United Kingdom
- Loughborough University
-
-
Participation Criteria
Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
No
Description
Inclusion Criteria:
- A self-reported history of heavy drinking
- At least one heavy drinking episode (≥8 units) in the last 28 days
Exclusion Criteria:
- Participants being under 18 years of age
- Supplementation of probiotics or prebiotics within the past 4 weeks
- Antibiotic use within the past 4 weeks
- Major psychiatric conditions diagnosed e.g., bipolar disorder, schizophrenia
- Current pregnancy or breastfeeding
- Having had a heavy drinking episode (≥8 units) in the last 12 hours
Study Plan
This section provides details of the study plan, including how the study is designed and what the study is measuring.
How is the study designed?
Design Details
- Primary Purpose: Treatment
- Allocation: Randomized
- Interventional Model: Parallel Assignment
- Masking: Quadruple
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Active Comparator: Probiotic Group
Capsules contain the active ingredient (live bacteria)
|
A probiotic is randomly administered to patients with alcohol use disorder
|
|
Placebo Comparator: Placebo Group
Capsules look identical to the probiotic but contain no live bacteria
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A placebo is randomly administered to patients with alcohol use disorder
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Recruitment Rate, Defined as the Proportion of Screened Participants Meeting Eligibility Criteria and Enrolling
Time Frame: From enrollment to the end of treatment at 4 weeks
|
Recruitment rate will be calculated as the number of participants enrolled divided by the total number of participants assessed for eligibility, expressed as a percentage.
|
From enrollment to the end of treatment at 4 weeks
|
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Retention Rate, Defined as the Proportion of Enrolled Participants Completing the 4-Week Intervention
Time Frame: From enrollment to the end of treatment at 4 weeks
|
Retention rate will be calculated as the number of participants completing the 4-week intervention divided by the total number enrolled, expressed as a percentage, and will be reported overall and by study arm.
|
From enrollment to the end of treatment at 4 weeks
|
|
Intervention Adherence, Assessed by Capsule Count
Time Frame: From enrollment to the end of treatment at 4 weeks
|
Adherence will be calculated as the number of capsules consumed relative to the 28 capsules prescribed across the 4-week intervention period, based on participant-reported capsule counts, and expressed as a percentage of the total prescribed dose.
|
From enrollment to the end of treatment at 4 weeks
|
|
Participant Acceptability, Assessed by Verbal Feedback
Time Frame: From enrollment to the end of treatment at 4 weeks
|
Acceptability of the intervention will be assessed via verbal feedback requested from the participants at the end of the 4-week intervention period, covering participants' experience of intervention components including capsule-taking and stool sample collection procedures.
|
From enrollment to the end of treatment at 4 weeks
|
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
38 participants with Alcohol Use Disorder assessed for Working Memory by n-back task
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Working memory will be assessed using a computerized N-back task (1-back, 2-back, 3-back conditions).
Participants respond when a stimulus matches one presented previously (1-3 trials earlier).
The task includes 50 trials per condition with 10 target stimuli.
Each stimulus is presented for 1000 ms.
Performance will be measured based on the number of commission errors (count) and number of correct responses (count), with higher correct responses indicating better working memory performance and higher commission errors indicating poorer performance.
|
From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Gut Microbiome Composition by 16S rRNA Gene Sequencing
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Gut health will be assessed using 16S ribosomal RNA (rRNA) gene sequencing of stool samples collected and analysed in the laboratory.
Microbial composition will be characterised using standard bioinformatics pipelines.
Outcomes will include alpha diversity (within-sample diversity; e.g., Shannon diversity index) and beta diversity (between-sample differences in microbial composition).
Performance will be measured as diversity indices (unitless values) and distance metrics for beta diversity, with higher alpha diversity generally indicating greater microbial diversity and gut health.
|
From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Alcohol Craving by Penn Alcohol Craving Scale
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Alcohol craving will be assessed using the Penn Alcohol Craving Scale (PACS), a 5-item self-report questionnaire measuring frequency, intensity, and duration of alcohol cravings over the past week.
Each item is rated on a scale from 0 to 6, yielding a total score ranging from 0 to 30.
Performance will be measured as the total PACS score (range 0-30), with higher scores indicating greater alcohol craving severity.
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From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Response Inhibition by Go/No-Go task
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Response inhibition will be assessed using a computerized Go/No-Go task.
Participants are required to respond to "go" stimuli and withhold responses to "no-go" stimuli.
Performance will be measured as the number of commission errors (responses during no-go trials; count) and the number of correct responses (correct responses to go trials; count), with higher commission errors indicating poorer response inhibition and higher correct responses indicating better task performance.
|
From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Depression, Anxiety, and Stress by Depression Anxiety Stress Scales-12
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Mental health symptoms will be assessed using the Depression Anxiety Stress Scales-12 (DASS-12), a 12-item self-report questionnaire measuring symptoms of depression, anxiety, and stress.
Each item is rated on a 4-point Likert scale (0-3), yielding a total score ranging from 0 to 36.
Performance will be measured as the total DASS-12 score (range 0-36), with higher scores indicating greater psychological distress.
|
From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Drinking Behaviour by Loughborough Alcohol Drinking Questionnaire
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Drinking behaviour will be assessed using the Loughborough Alcohol Drinking Questionnaire (LoAD-Q), a 33-item self-report questionnaire measuring three dimensions: emotional drinking, external drinking, and restrained drinking. Each item is rated on a 5-point Likert scale (1 = never to 5 = very often). Subscale scores are calculated by summing item responses within each dimension. The emotional drinking subscale (13 items) has a score range of 13 to 65, the external drinking subscale (10 items) ranges from 10 to 50, and the restrained drinking subscale (10 items) ranges from 10 to 50. Performance will be measured as subscale total scores, with higher scores indicating greater levels of emotional, external, and restrained drinking behaviour, respectively. |
From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Attention by Visual Search task
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Attention will be assessed using a computerized visual search task in which participants identify target stimuli among distractors.
Performance will be measured as reaction time (milliseconds) and accuracy (percentage of correct responses, %) across trials, with lower reaction times indicating better attentional performance and higher accuracy indicating better task performance.
|
From enrollment to the end of the treatment at 4 weeks
|
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38 participants with Alcohol Use Disorder assessed for Cognitive Bias by Rough Estimation Task
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Cognitive bias will be assessed using the Rough Estimation Task (REsT), where participants read a list of alcohol-related, semantically related, and unrelated words and estimate the proportion of alcohol-related words.
Performance will be measured as the percentage (%) of words estimated as alcohol-related, with overestimation (>33%) indicating cognitive bias.
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From enrollment to the end of the treatment at 4 weeks
|
Other Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
38 participants with Alcohol Use Disorder assessed for Inflammation by Salivary Interleukin-6 (IL-6) using Enzyme-Linked Immunosorbent Assay (ELISA)
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Inflammation will be assessed using salivary interleukin-6 (IL-6) measured via enzyme-linked immunosorbent assay (ELISA) using commercially available kits according to manufacturer protocols.
Performance will be measured as IL-6 concentration in picograms per millilitre (pg/mL), with higher values indicating greater systemic inflammation.
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From enrollment to the end of the treatment at 4 weeks
|
|
38 participants with Alcohol Use Disorder assessed for Disordered Eating by Eating Disorder Examination Questionnaire Short Form
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Disordered eating behaviours will be assessed using the Eating Disorder Examination Questionnaire Short Form (EDE-QS), a 12-item self-report questionnaire measuring eating disorder psychopathology over the past 7 days.
Each item is rated on a 4-point scale (0-3), yielding a total score ranging from 0 to 36.
Performance will be measured as the total EDE-QS score (range 0-36), with higher scores indicating greater severity of disordered eating behaviours.
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From enrollment to the end of the treatment at 4 weeks
|
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38 participants with Alcohol Use Disorder assessed for Physiological Stress by Salivary Cortisol using Enzyme-Linked Immunosorbent Assay (ELISA)
Time Frame: From enrollment to the end of the treatment at 4 weeks
|
Physiological stress will be assessed using salivary cortisol measured via enzyme-linked immunosorbent assay (ELISA) using commercially available kits according to manufacturer protocols.
Performance will be measured as cortisol concentration in nanomoles per litre (nmol/L), with higher values indicating greater physiological stress.
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From enrollment to the end of the treatment at 4 weeks
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Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Sponsor
Study record dates
These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.
Study Major Dates
Study Start (Actual)
December 15, 2025
Primary Completion (Actual)
April 17, 2026
Study Completion (Actual)
May 17, 2026
Study Registration Dates
First Submitted
March 19, 2026
First Submitted That Met QC Criteria
March 27, 2026
First Posted (Actual)
April 3, 2026
Study Record Updates
Last Update Posted (Actual)
September 15, 2026
Last Update Submitted That Met QC Criteria
September 10, 2026
Last Verified
September 1, 2026
More Information
Terms related to this study
Additional Relevant MeSH Terms
Other Study ID Numbers
- 22834
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
UNDECIDED
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
No
Studies a U.S. FDA-regulated device product
No
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