Colon-delivered riboflavin and the gut microbiome in older adults

The Benefit of Colon-delivered Riboflavin (Riboflavin-cd) vs. Conventional Riboflavin on Gut Microbiota Composition and Metabolic Output in Healthy Aging Subjects - a Pilot Proof of Concept Study

This test will see if riboflavin released in the colon changes gut bacteria and improves bowel complaints in adults aged 50–70.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 90 (estimated)
• Ages: 50 Years to 70 Years
• Sex: All
• Sponsor: dsm-firmenich Switzerland AG (industry)
• Locations: 1 site (Berlin, State of Berlin)
• Trial ID: NCT07093463 on ClinicalTrials.gov

What this trial studies

This interventional study will compare three oral preparations given to participants aged 50–70: colon-targeted riboflavin, conventional riboflavin, and an inert placebo. Participants with self-reported moderate bowel complaints and stable body weight will receive one of the products and undergo measurements of gut microbiota composition, microbial metabolic activity, and gut symptom scores. Outcomes likely include stool sampling for microbiome analysis, metabolic readouts, and validated symptom questionnaires over the treatment period. The goal is to determine whether local delivery of vitamin B2 to the colon produces different microbial and clinical effects than standard systemic vitamin formulations or placebo.

Who should consider this trial

Good fit: Ideal candidates are generally healthy men and menopausal women aged 50–70 with a BMI of 18.5–29.9, stable weight, and self-reported moderate bowel complaints as measured by the GSRS.

Not a fit: People outside the 50–70 age range, those without moderate bowel complaints, or those with significant medical or gastrointestinal disease are unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, colon-delivered riboflavin could shift gut microbial composition and help relieve moderate bowel symptoms in older adults.

How similar studies have performed: Previous small studies and laboratory work suggest B‑vitamins can have prebiotic-like effects, but clinical benefits specifically from colon-targeted vitamin delivery remain largely unproven.

Eligibility criteria

Inclusion Criteria:

1. Individuals providing written informed consent for participation in the study and data processing
2. Female and males between 50 and 70 years of age
3. For females only: Menopausal as marked by at least 1 year since the last menstrual bleeding
4. Individuals with a BMI between 18.5 - 29.9 Kg/m2
5. Individuals with stable body weight (≤5% change) over the past 3 months prior to V1
6. Individuals with self-reported moderate bowel complaints in at least last 3 months prior to V1
7. Individuals with GSRS score suggestive of moderate bowel complaints, as assessed at V1, for the average condition over the 4 last weeks (all GSRS items have to be answered at V1): • indigestion score 3-5 or constipation score 3-5 or diarrhoea score 3-5
8. Individuals with a general good health, as determined by questioning, clinical examination and vital signs (blood pressure, pulse rate) by the investigator at V1
9. Individuals willing to avoid consuming gut microbiome modulating dietary supplements, prebiotic, probiotic, synbiotic or fibre-rich supplements during the entire study duration
10. Individuals willing to maintain current level of physical activity throughout the entire study duration
11. If individuals are taking chronic medications (e.g., antihypertensive medications), they must be willing and expected to maintain the same dosage throughout the study

Exclusion Criteria:

1. Individuals who are hypersensitive/intolerant to any of the components of the Investigational product or the standardised diet addition (inulin)
2. Individuals who have taken systemic antibiotics within the previous 3 months prior to Baseline (V2) or are expected to be taking any during the study
3. Individuals who consumed microbiome modulating dietary supplements, prebiotic, probiotic, or fibre-rich supplements within 4 weeks prior to the baseline (V2)
4. Individuals who are currently regularly using systemic steroids, proton pump inhibitors, H2 blocker, antacids (however, sporadic use during the study if needed is allowed, but not within 8 hours before each visit), metformin if started less than 6 months prior to V1, or immunosuppressant medication.
5. Individuals who have a history of drug abuse in the previous 5 years and/or alcohol abuse at the time of enrolment (\>11 units/week for women; \>17 units/week for men; unit: approx. 125 mL of wine or similar / approx. 30 mL of spirits

   / approx. 280 mL beer or similar); Is currently in treatment for alcohol/substance abuse; Has been diagnosed with alcohol/substance abuse disorder)
6. Individuals who are a smoker or vaper
7. Individuals who are vegetarian or vegan
8. Individuals who have made any major dietary changes in the past 3 months prior to Baseline (V2)
9. Individuals who have planned major changes in the lifestyle (i.e., diet, dieting, exercise level, significant travel) during the duration of the study.
10. Individuals who have a currently present active eating disorder
11. Individuals with self-reported food allergy / intolerance (e.g., lactose, gluten, fructose), as determined by the study investigator
12. Clinical significance for any of screening laboratory test results from the blood draw at V1, as per investigator's judgement
13. Individuals with a self-reported fibre-rich regular diet, as per investigator's judgement
14. Individuals who have a (self-reported) gastrointestinal disorder/disease (e.g., chronic/recurrent diarrhoea, inflammatory bowel disorder, irritable bowel syndrome, diverticulosis, stomach or duodenal ulcers, bile acid malabsorption) or previous gastrointestinal surgery (such as bariatric surgery, colon specific surgical interventions etc.), which in the opinion of the investigator would impact the study outcomes
15. Individuals with GSRS assessed at V1 for the average condition over the 4 last weeks prior to V1 for any score (abdominal pain, reflux score, indigestion, constipation, diarrhoea) \>5 (all GSRS items have to be answered at V1)
16. Individuals who have severe or uncontrolled conditions such as type 2 diabetes (FBG ≥ 150 mg/dl from blood draw at V1), psychiatric disorder, respiratory or cardiac illness or any other condition which in the opinion of the investigator would impact the study outcomes
17. Individuals who have a history of any gastrointestinal cancer
18. Individuals who are severely immunocompromised
19. Individuals with alarm features in the past 3 months prior to V1 such as unintentional weight loss (≤5% change), fever, anorectal problems, blood in stool, vomiting
20. 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 requirements
21. If Individuals have been in a recent experimental study, this must have been completed not less than 30 days prior to this study

Where this trial is running

Berlin, State of Berlin

• analyze & realize GmbH — Berlin, State of Berlin, Germany (RECRUITING)

Study contacts

• Study coordinator: Veronika Bobb, Dr.

Conditions: Microbiome Dysbiosis, Gut Health, elderly, microbiome, colon delivered b-vitamins, riboflavin