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Healthy ParticipantsNCT07840066

Probiotics in Wellbeing

A study testing Probiotic Supplementation (Lactobacillus plantarum) in people with Healthy Participants, run by University of Reading at 1 site in United Kingdom.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This study will investigate whether taking a probiotic supplement every day for 12 weeks can reduce low-level inflammation and improve wellbeing in generally healthy adults. Forty adults will be randomly assigned to receive either a probiotic capsule or a placebo capsule that looks the same but does not contain… Read more about this study

Who is it for?
Ages 18 to 60 yearsHealthy volunteers can take part
Conditions the study is for
Healthy Participants
What is being tested?
Probiotic Supplementation (Lactobacillus plantarum)
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
40 participants
Where
1 siteUnited Kingdom
Study dates
1 Sep 2026to Sep 2027
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 60 years
  • All sexes
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • Generally healthy adults
  • Aged 18 to 60 years
  • Body mass index (BMI) 18.5 to 30 kg/m²

Who cannot join

  • Antibiotic use within the previous 3 months
  • Chronic gastrointestinal disorders
  • Chronic immune disorders
  • Current probiotic or prebiotic use
  • Current use of immunomodulatory medication
  • Pregnancy or lactation
  • Relevant allergies

Trial locations and contacts

1 site in 1 country.

United Kingdom1 site
  • The University of Reading

    Reading, Berkshire, RG66DX

Other trials in United Kingdom

About this study

Official title: A Randomised Controlled Trial Investigating the Probiotic-mediated Suppression of Inflammatory Cytokines as a Mechanism for Improving Wellbeing

This study will investigate whether taking a probiotic supplement every day for 12 weeks can reduce low-level inflammation and improve wellbeing in generally healthy adults.

Forty adults will be randomly assigned to receive either a probiotic capsule or a placebo capsule that looks the same but does not contain probiotic bacteria. Neither the participants nor the researchers involved in the study will know which treatment each participant receives until the study is completed.

Read more

Participants will attend a study visit before starting the supplement and another visit after 12 weeks, with a remote check midway through the study. Blood samples will be collected to measure markers of inflammation and stress. Stool samples will be collected to assess the gut microbiota and substances produced by gut bacteria. Urine samples will also be collected to measure metabolites, which are small molecules produced by normal processes in the body and by interactions between the body, diet and gut microbiota. Participants will also complete questionnaires about wellbeing, mood, anxiety, quality of life and memory.

The main aim of the study is to determine whether the probiotic reduces a combined measure of several markers of inflammation compared with placebo. The study will also explore whether changes in inflammation are associated with changes in wellbeing and memory, and whether these effects are accompanied by changes in the gut microbiota or in metabolic profiles measured in stool and urine.

The results will help researchers understand how probiotics may influence communication between the gut, immune system and brain, and will provide information to help design a larger clinical trial.

Read the detailed description

The gut microbiota can influence host immune function through interactions with the intestinal barrier, microbial metabolites and systemic immune signalling. In turn, systemic inflammatory mediators have been associated with mood, wellbeing and cognitive function. This study will investigate a proposed gut-immune-brain pathway in which modulation of the gut environment by a probiotic intervention may alter systemic inflammatory signalling and thereby influence psychological wellbeing and cognitive function.

This is a 12-week, randomised, double-blind, placebo-controlled, parallel-arm pilot study in 40 generally healthy adults. Following baseline assessments, participants will be randomly allocated to receive either a daily multi-strain probiotic supplement or a matched placebo for 12 weeks. Assessments will take place at baseline and at the end of the 12-week intervention, with a remote adherence and tolerability check approximately halfway through the intervention.

The primary objective is to determine whether probiotic supplementation reduces systemic pro-inflammatory activity compared with placebo. The primary endpoint is the change from baseline to week 12 in a pre-specified pro-inflammatory composite comprising IL-6, TNF-α, IL-1β, IL-8, IFN-γ and high-sensitivity C-reactive protein (hsCRP). Each marker will be standardised relative to its baseline variability and combined into a direction-consistent composite in which higher values indicate greater inflammatory activity.

Secondary assessments will include the anti-inflammatory cytokine IL-10, serum cortisol and validated questionnaires assessing quality of life, depressive symptoms, anxiety, wellbeing and prospective and retrospective memory.

Exploratory mechanistic outcomes will include faecal short-chain fatty acids and related organic acids measured by gas chromatography-mass spectrometry, quantification of selected major bacterial groups using fluorescence in situ hybridisation coupled with flow cytometry, and descriptive 16S rRNA gene sequencing to characterise gut microbial community features. Urine samples collected at baseline and week 12 will undergo nuclear magnetic resonance (NMR) spectroscopy-based metabolomic profiling to assess changes in urinary metabolites associated with the intervention. These analyses will provide an additional measure of host-microbial metabolic activity and will be explored in relation to changes in the gut microbiota, inflammatory markers and wellbeing outcomes.

The study will additionally examine whether within-person reductions in the pro-inflammatory composite are associated with improvements in wellbeing and cognitive measures, whether this relationship differs between the probiotic and placebo groups, and whether baseline inflammatory status modifies the response to the intervention. Exploratory mediation analyses will investigate whether changes in inflammatory activity may partly account for any observed effect of the intervention on wellbeing.

By integrating measures of gut microbial composition and activity, faecal and urinary metabolite profiles, systemic immune signalling and psychological outcomes within a controlled intervention study, the trial aims to improve mechanistic understanding of communication along the gut-immune-brain axis and to provide effect-size and feasibility data for a future larger randomised controlled trial.

Being tested
Probiotic Supplementation (Lactobacillus plantarum), Daily oral administration of one matched placebo capsule for 12 weeks. The placebo contains potato starch in place of the probiotic bacterial mass and is matched to the active intervention.

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Probiotic Supplementation (Lactobacillus plantarum)Dietary supplement

    Also called Optibac Every Day Probiotic

    Daily oral administration of one capsule of a multi-strain probiotic supplement (Optibac "Every Day") for 12 weeks. Each daily dose provides 5 × 10⁹ CFU and contains Lactobacillus rhamnosus Rosell-11 (R0011), Lactobacillus acidophilus/helveticus Rosell-52 (R0052), Bifidobacterium longum Rosell-175 (R0175), Bifidobacterium breve Rosell-70 (R0070), Bifidobacterium bifidum Rosell-71 (R0071), and Lactococcus lactis Rosell-1058 (R1058), together with fructooligosaccharides (FOS). Participants will take one capsule daily with water for 12 weeks, beginning the day after baseline sampling.

  • Daily oral administration of one matched placebo capsule for 12 weeks. The placebo contains potato starch in place of the probiotic bacterial mass and is matched to the active intervention.Dietary supplement

    Daily oral administration of one matched placebo capsule for 12 weeks. The placebo contains potato starch in place of the probiotic bacterial mass and is matched to the active intervention in capsule shell, appearance and fill weight. Participants will take one capsule daily with water for 12 weeks, beginning the day after baseline sampling.

Study groups in NCT07840066
Study groupRoleWhat they receive
Vegan capsules filled with potato starch only.Placebo comparatorDaily oral administration of one matched placebo capsule for 12 weeks. The placebo contains potato starch in place of the probiotic bacterial mass and is matched to the active intervention in capsule shell, appearance and fill weight. Participants will take one capsule daily with water for 12 weeks, beginning the day after baseline sampling.
Receives: Dietary Supplement: Daily oral administration of one matched placebo capsule for 12 weeks. The placebo contains potato starch in place of the probiotic bacterial mass and is matched to the active intervention.
Probiotic supplementExperimentalDaily oral administration of one capsule of a multi-strain probiotic supplement (Optibac "Every Day") for 12 weeks. Each daily dose provides 5 × 10⁹ CFU and contains Lactobacillus rhamnosus Rosell-11 (R0011), Lactobacillus acidophilus/helveticus Rosell-52 (R0052), Bifidobacterium longum Rosell-175 (R0175), Bifidobacterium breve Rosell-70 (R0070), Bifidobacterium bifidum Rosell-71 (R0071), and Lactococcus lactis Rosell-1058 (R1058), together with fructooligosaccharides (FOS). Participants will take one capsule daily with water for 12 weeks, beginning the day after baseline sampling.
Receives: Dietary Supplement: Probiotic Supplementation (Lactobacillus plantarum)

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change in standardised pro-inflammatory biomarker composite

    Change from baseline to Week 12 in a pre-specified pro-inflammatory composite comprising IL-6, TNF-α, IL-1β, IL-8, IFN-γ and high-sensitivity C-reactive protein (hsCRP). Each biomarker will be standardised relative to its baseline distribution and the composite calculated as the mean of direction-consistent z-scores. This is a study-defined continuous composite rather than a bounded clinical scale; therefore, it has no fixed theoretical minimum or maximum. Higher composite values indicate greater systemic inflammatory activity, and a negative change from baseline indicates a reduction in inflammatory activity. The between-group change will be compared between the probiotic and placebo groups.

    Measured: Baseline and Week 12

Secondary outcomes (8)
  1. Change in plasma IL-10 concentration

    Change from baseline to Week 12 in plasma interleukin-10 (IL-10), an anti-inflammatory cytokine. IL-10 will be assessed as a secondary marker of anti-inflammatory immune activity.

    Measured: Baseline and Week 12

  2. Change in serum cortisol concentration

    Change from baseline to Week 12 in serum cortisol concentration as a secondary measure related to physiological stress responses.

    Measured: Baseline and Week 12

  3. Change in 12-Item Short Form Health Survey Mental Component Summary score

    Change from baseline to Week 12 in mental health-related quality of life assessed using the 12-Item Short Form Health Survey, Version 1 (SF-12v1) Mental Component Summary (MCS). MCS scores range from 0 to 100, with higher scores indicating better mental health-related quality of life. Change will be calculated as Week 12 minus baseline; a positive change indicates improvement.

    Measured: Baseline and Week 12

  4. Change in 12-Item Short Form Health Survey Physical Component Summary score

    Change from baseline to Week 12 in physical health-related quality of life assessed using the 12-Item Short Form Health Survey, Version 1 (SF-12v1) Physical Component Summary (PCS). PCS scores range from 0 to 100, with higher scores indicating better physical health-related quality of life. Change will be calculated as Week 12 minus baseline; a positive change indicates improvement.

    Measured: Baseline and Week 12

  5. Change in Patient Health Questionnaire-9 total score

    Change from baseline to Week 12 in depressive symptom severity assessed using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 total score ranges from 0 to 27, with higher scores indicating greater depressive symptom severity. Change is calculated as Week 12 minus baseline; a negative change indicates improvement.

    Measured: Baseline and Week 12

  6. Change in Generalized Anxiety Disorder-7 total score

    Change from baseline to Week 12 in anxiety symptom severity assessed using the Generalized Anxiety Disorder-7 (GAD-7). The GAD-7 total score ranges from 0 to 21, with higher scores indicating greater anxiety symptom severity. Change is calculated as Week 12 minus baseline; a negative change indicates improvement.

    Measured: Baseline and Week 12

  7. Change in World Health Organization-Five Well-Being Index score

    Change from baseline to Week 12 in psychological wellbeing assessed using the World Health Organization-Five Well-Being Index (WHO-5). The raw WHO-5 score ranges from 0 to 25, with higher scores indicating better mental wellbeing. Change is calculated as Week 12 minus baseline; a positive change indicates improvement.

    Measured: Baseline and Week 12

  8. Change in Prospective and Retrospective Memory Questionnaire total score

    Change from baseline to Week 12 in self-reported everyday memory failures assessed using the 16-item Prospective and Retrospective Memory Questionnaire (PRMQ). The total PRMQ score ranges from 16 to 80, with higher scores indicating more frequent self-reported memory failures and therefore a worse outcome. Change is calculated as Week 12 minus baseline; a negative change indicates improvement.

    Measured: Baseline and Week 12

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted24 Sep 2026
  2. Study start1 Sep 2026
  3. Primary completion1 Aug 2027 (estimated)
  4. Study completionSep 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Basic science
Allocation
Randomised
Intervention model
Parallel groups
Model description
Two-arm, randomised, double-blind, placebo-controlled, parallel-group study. Participants will be allocated 1:1 to receive either a daily multi-strain probiotic supplement or matched placebo for 12 weeks.
Masking
Triple blind
Who is masked
Participant, Investigator, Outcomes assessor
Enrolment
40 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07840066
Sponsor's protocol ID
26/20
Other IDs
UKRI775
Status last verified
Sep 2026
First submitted
14 Sep 2026
Last updated
24 Sep 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Undecided

Questions about this trial

What is this clinical trial studying?

A study testing Probiotic Supplementation (Lactobacillus plantarum) in people with Healthy Participants, run by University of Reading at 1 site in United Kingdom.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 24 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in standardised pro-inflammatory biomarker composite (time frame: Baseline and Week 12). It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Sep 2026.

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