How vitamin C affects gut bacteria and their activity in healthy adults
The Effect of Vitamin C Supplementation on Gut Microbiota Composition and Metabolic Activity in Healthy Adults
This study will test whether taking a moderate (200 mg) then a high (1000 mg) daily dose of vitamin C changes gut bacteria composition and short-chain fatty acid levels in healthy adults.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 23 (estimated) |
| Ages | 18 Years to 65 Years |
| Sex | All |
| Sponsor | University of Glasgow Academic / other |
| Locations | 1 site (Glasgow) |
| Trial ID | NCT07388121 on ClinicalTrials.gov |
What this trial studies
This sequential dietary intervention recruits 23 healthy adults in Glasgow who will follow their habitual diet for one week, then take 200 mg/day vitamin C for two weeks followed immediately by 1000 mg/day for two weeks, with a final one-week follow-up. Stool, blood, and urine samples will be collected at four visits to measure gut microbiota composition and short-chain fatty acid (SCFA) production as primary outcomes, with exploratory measures of systemic inflammation and gut barrier integrity. Participants will be instructed to maintain their usual diet and lifestyle and there is no washout period between dosing phases. All visits take place at the New Lister Building, University of Glasgow.
Who should consider this trial
Good fit: Healthy adults aged 18–65 with BMI 18.5–35 kg/m2 who live near Glasgow and are willing to provide stool, blood, and urine samples and avoid other supplements before and during the study.
Not a fit: People who are smokers, pregnant or breastfeeding, have recent antibiotic use, chronic illnesses, major gastrointestinal surgery, or cannot stop probiotics/vitamins are unlikely to benefit or be eligible.
Why it matters
Potential benefit: If successful, this could identify vitamin C doses that boost beneficial gut bacteria and increase health-related stool SCFAs, helping to inform dietary guidance.
How similar studies have performed: Some small human and animal studies suggest dietary vitamins can alter gut microbes, but dose-response data specifically for vitamin C in healthy adults are limited and this approach is relatively novel.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Healthy individuals aged 18-65 years with a BMI between 18.5-35 Kg/m2 * Self-reported good health with no chronic conditions requiring regular medical care * Willing to provide blood, urine, and stool samples at multiple time points Exclusion Criteria: * Aged \<18 or \>65 years * Smoking * Chronic illness requiring regular medication or GP visits * Current or recent medication affecting gut transit or digestion * Major gastrointestinal surgery * Pregnant or breastfeeding * Regular use of pre/probiotics, vitamins, or minerals (unless willing to discontinue 2-4 weeks prior) * Antibiotics in past 3 months * Weight change \>±2 kg in past month * Participation in other research likely to interfere with this study
Where this trial is running
Glasgow
- New Lister Building, Glasgow Royal Infirmary, 10-16 Alexandra Parade, G31 2ER — Glasgow, United Kingdom (Recruiting)
Study contacts
- Principal investigator: Athanasios Koutsos, PhD — Human Nutrition, School of Medicine, College of Medical, Veterinary, and Life Sciences, University of Glasgow
- Study coordinator: Raihana Halim
- Email: 2859495H@student.gla.ac.uk
- Phone: 07857 725347
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.