Probiotic Research: Open-label Functional Intervention and Longitudinal Evaluation in Healthy Adults

Overview

This study is a pre-post, open-label cohort study designed to investigate how a food-grade probiotic supplement affects biological measurements and wellbeing in healthy adults. Participants will take one capsule daily for either 1 month or 6 months. During the study, participants will complete online cognitive tasks and provide blood and stool samples collected during home visits by trained staff. The samples will be analysed to explore changes in gut bacteria and other biological markers. This study aims to understand whether the supplement is well tolerated and whether measurable biological changes occur. The study does not involve any experimental drugs or invasive procedures beyond blood sampling and stool collection, and participants will not be asked to change any current prescribed medications or treatments; with eligibility exclusions applying for recent antibiotics or immunosuppressants. The supplement is being studied for research purposes only and is not intended to diagnose, treat, or prevent disease. Participants will be invited to participate in a follow-up visit to assess long-term effects.

Interventions

• Dietary supplement Probiotic Supplementation (Lactobacillus plantarum)
  This probiotic is a proprietary food-grade supplement that is not yet commercially available or CE-marked.

Primary outcome measures

• Changes in metagenome of stool samples [Time frame: From enrolment to the end of treatment at 4 or 24 weeks respectively. Optionally, a follow-up measure may be offered 24 weeks after the end of treatment.]

Secondary outcome measures (6)

• Change in blood multiome [Time frame: From enrolment to the end of treatment at 4 or 24 weeks respectively. Optionally, a follow-up measure may be offered 24 weeks after the end of treatment.]
• Changes in cognition [Time frame: Assessed weekly from enrolment and to end of treatment at 4 or 24 weeks respectively.]
• Change in daytime sleepiness [Time frame: Assessed at enrolment and at end of treatment at 4 or 24 weeks respectively.]
• Change in sleep quality [Time frame: Assessed at enrolment and at end of treatment at 4 or 24 weeks respectively.]
• Change in self-reported wellbeing and mood [Time frame: Assessed at enrolment and at end of treatment at 4 or 24 weeks respectively.]
• Adverse event monitoring [Time frame: Assessed from enrolment until end of treatment at 4 or 24 weeks respectively.]

Eligibility criteria

Inclusion criteria

• Aged 18 years or older at the time of providing informed consent.
• In generally good health, with no known medical conditions that could interfere with the aims of the study or participant safety, as judged by self-report and screening questionnaire.
• No history of significant psychiatric or neurological illness
• Ability to complete study specific tasks, including:
• Daily oral intake of a probiotic capsule
• Self-collection of stool samples
• Completion of online questionnaires and simple cognitive tasks
• Able to read, understand, and communicate in English, in order to give informed consent and follow study instructions.
• Access to the internet and a suitable device (e.g., smartphone, tablet, or computer) for completing online aspects of the study.

Exclusion criteria

• Participants will be excluded from the study if any of the following criteria apply:
• Use of any systemic antibiotic or systemic immunosuppressive medication within the past 8 weeks, including but not limited to:
• β-lactam antibiotics, macrolides, tetracyclines, fluoroquinolones, aminoglycosides, glycopeptides, sulfonamides, antimycobacterial agents, systemic antifungals or antivirals
• Use of any systemic immunosuppressants within the past 16 weeks, including, but not limited to:
• Systemic corticosteroids, conventional immunosuppressants, biologic immunomodulators, targeted synthetic immunosuppressants, cytotoxic chemotherapy, or transplant-related immunosuppression.
• A longer exclusion window is applied for systemic immunosuppressive therapies due to their prolonged and potentially lasting effects on immune function and gut microbial composition compared with systemic antibiotics.
• Participants who commence systemic antibiotics or immunosuppressive therapy after enrolment will not be withdrawn from safety monitoring but will stop the supplement and will not continue the intervention phase of the study. With participant consent, data collected may still be used.
• Major gastrointestinal disease or surgery:
• Any history of significant gastrointestinal disease or surgery that may alter gut microbiome composition, immune function, or nutrient absorption, including but not limited to inflammatory bowel disease (Crohn's disease, ulcerative colitis, indeterminate colitis); coeliac disease or other chronic malabsorptive disorders; chronic liver, biliary, or pancreatic disease; moderate-to-severe or unstable irritable bowel syndrome; gastrointestinal malignancy; chronic gastrointestinal motility disorders; recurrent Clostridioides difficile infection; or any major gastrointestinal surgery such as bowel resection, bariatric surgery, colectomy, ileostomy or colostomy. Prior appendectomy or cholecystectomy alone is not exclusionary.
• Current pregnancy or development of pregnancy, breastfeeding
• Known allergy to probiotic or compounding ingredients:
• Vitamin D3
• Isomaltooligosaccharide
• Yeast extract

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Basic science

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07457242 · PROFILE

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗