The Effect of Vitamin C Supplementation on Gut Microbiota Composition and Function in Healthy Adults

The aim of this dietary intervention study is to explore how vitamin C affects the bacteria that live in our gut. Vitamins are essential nutrients found in fruits and vegetables. Our bodies cannot make them on their own, but we need them to function correctly. Vitamins play various roles, including supporting the immune system and assisting with energy production. Some vitamins in our diet can reach the large intestine, where they may be used by gut bacteria to promote their growth. In this study, we aim to investigate how our gut bacteria interact with vitamin C and how this interaction affects their growth and activity. For this study, participants will follow their habitual diet for one-week (run-in period), followed by two consecutive two-week supplementation periods in which they will first take a moderate dose (200 mg/day) and then a high-dose (1000 mg/day) of vitamin C. A final one-week period follow up period will involve a return to their habitual diet. Faecal, blood and urine samples will be collected at the start and end of each supplementation period to explore changes in gut microbiota composition, activity and markers of inflammation.

NCT Number	NCT07388121
Lead Sponsor	University of Glasgow Collaborators: Professor Konstantinos Gerasimidis, University of Glasgow
Conditions	Short Chain Fatty Acids Concentration in Stools, Gut Microbiota Diversity and Composition
Enrollment	23 participants
Start Date	2025-11-01
Primary Completion	2026-07-01 (estimated)
Study Completion	2026-07-01 (estimated)
Updated on ClinicalTrials.gov	2026-02-04