Synbiotic to improve gut barrier and microbiota in middle-aged and older adults with excess weight

The Effect of a Synbiotic on Intestinal Barrier Function and Microbiota Modulation in Middle-aged to Elderly Individuals With Excessive Body Weight: a Randomized, Double-blind, Placebo-controlled Study

This study will test whether a synbiotic (two probiotic strains plus a prebiotic) can improve gut barrier function, shift gut bacteria, and reduce gastrointestinal discomfort in people aged 50–70 with BMI 25–35 and mild bowel symptoms.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 90 (estimated)
• Ages: 50 Years to 70 Years
• Sex: All
• Sponsor: Novonesis (Industry-sponsored)
• Locations: 1 site (Cork, Blackpool)
• Trial ID: NCT07453823 on ClinicalTrials.gov

What this trial studies

This is a randomized, double-blind, placebo-controlled intervention with an 8-week daily synbiotic or placebo period followed by a 2-week follow-up. Participants complete a run-in diary to confirm symptom levels and bowel frequency before randomization. Outcomes include measures of intestinal permeability and integrity, changes in gut microbiota composition, and patient-reported gastrointestinal symptoms. The trial enrolls middle-aged to elderly adults with overweight and mild-to-moderate GI complaints and low bowel frequency.

Who should consider this trial

Good fit: Adults aged 50–70 with BMI 25.0–35.0 kg/m² who report mild-to-moderate GI complaints (GSRS-IBS score 20–45) and low bowel frequency during the run-in period are ideal candidates.

Not a fit: People outside the 50–70 age or BMI 25–35 range, those without the specified symptom profile or bowel-frequency criteria, or those with significant gastrointestinal disease or recent interfering treatments are unlikely to benefit.

Why it matters

Potential benefit: If successful, the synbiotic could reduce gastrointestinal discomfort and improve markers of gut barrier integrity and microbial balance in the target group.

How similar studies have performed: Previous synbiotic and probiotic studies have shown mixed but sometimes promising effects on microbiota composition and modest improvements in permeability or symptoms in selected populations.

Eligibility criteria

Inclusion Criteria:

1. Be able to give informed consent.
2. Be between 50 to 70 years of age (inclusive).
3. BMI ranging from 25.0 and 35.0 kg/m²
4. Willing to maintain current level of physical activity and diet during the participation in the study.
5. Experience ≤3 bowel movements per week within the month prior to screening
6. Participants reported subclinical mild to moderate gastrointestinal complaints as defined by GSRS-IBS score 20-45 at screening.
7. Willing to consume the study product daily for the duration of the study.
8. Willing to eat the same meal the evening before visiting site (visit 2 to visit 5).

Participants are eligible for randomization if they fulfill the following two criteria based on the diary recordings during the run-in period prior to visit 2 9. Average GSRS-IBS composite symptom score between 20-45 during the two-week run-in period Record ≤6 bowel movements in the daily diary during the two-week run-in period

Exclusion Criteria:

1. Has a history of drug and/or alcohol abuse.
2. Has food allergies, or other issues with foods, that would preclude intake of the study products.
3. Smoking, chewable tobacco and/or vaping and/or use of other nicotine products.
4. Has any significant acute or chronic coexisting health conditions that would prevent them from fulfilling the study requirements, put the Participant at risk or would confound the interpretation of the study results as judged by the investigator on the basis of medical history and routine laboratory test results. Excluded health conditions include:

   1. diagnosis of GI disease (e.g. gastric or duodenal ulcers, inflammatory bowel disease, colon cancer) or irritable bowel syndrome (IBS)
   2. GI surgery that might have an effect on gastrointestinal tract function except cholecystectomy and appendectomy in the past 5 years or any major bowel resection at any time.
   3. history of CVD
   4. uncontrolled hypertension
5. Currently or recently taking a medication that the investigator believes would interfere with the objectives of the study or pose a safety risk or confound the interpretation of the study results. Prohibited medications include:

   1. systemic antimicrobial medication (including suppositories) within 4 weeks prior to visit 1
   2. OTC medications, for digestive symptoms such as PPIs, anti-spasmodics, laxatives, anti-diarrheic drugs within 2 weeks prior to visit 1

10\. Individuals who, in the opinion of the investigator, are considered to be poor attendees or unlikely for any reason to be able to comply with the study.

11\. Participants may not be participating in other clinical studies. If the participant has previously taken part in an experimental study, the Investigator must ensure sufficient time has elapsed before entry to this study to ensure the integrity of the results.

c. immunosuppressant drugs within the 4 weeks prior to the visit 1 d. systemic steroids within the 4 weeks prior to the visit 1 6. Regular oral non-steroidal anti-inflammatory (NSAIDs) within 1 week prior to visit 1 (topical NSAIDS allowed, Low-dose prophylactic aspirin use is acceptable if stable for 3 months prior to screening.) 7. Current or recent (in the past 4 weeks prior to visit 1) use of prohibited nutritional and non-nutritional supplements, that the investigator believes would interfere with the objectives of the study or pose a safety risk or confound the interpretation of the study results, including:

a. Herbal supplements for digestive symptoms b. Large doses of vitamins and minerals, unless in stable dose c. Probiotic supplements d. Iron supplements 8. Current or recent (in the past 2-weeks) use of prohibited foods including yoghurts containing probiotics.

9\. Planned major changes in lifestyle \[i.e., diet (e.g. start of fibre-enriched diet), dieting, exercise level, travelling\] during the duration of the study.

Where this trial is running

Cork, Blackpool

• Atlantia Clinical Trials Ltd — Cork, Blackpool, Ireland (Recruiting)

Study contacts

• Principal investigator: Timothy G Dinan, Professor — Atlantia Clinical Trials Ltd
• Study coordinator: Sara Engel, PhD

Conditions Gastrointestinal Microbiome; Gastrointestinal Symptoms; Synbiotic