Anti-inflammatory Activities of Vitamin C Supplementation on the Gut Barrier Function in Adults With Obesity

NCT ID: NCT07151105

Last Updated: 2025-10-24

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 34 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-10-01
• Study Completion Date: 2026-12-30

Brief Summary

This study is testing whether taking vitamin C every day can help improve gut health and reduce inflammation in adults with obesity. Poor gut health-sometimes called "leaky gut"-can allow harmful substances from bacteria to enter the bloodstream, which may lead to inflammation and increase the risk of heart disease and liver problems.

Participants will complete two study periods, each lasting two weeks, with a two-week break in between. In one period, they will take vitamin C; in the other, a placebo. During each period, researchers will collect blood, urine, and stool samples, ask participants to track their diet and activity, and perform a test to measure gut permeability.

There are minimal risks, such as discomfort from blood draws or temporary stomach upset from a sugar drink. While participants may not directly benefit, their involvement will help researchers learn whether vitamin C is a safe and effective way to improve gut health in people with obesity.

Detailed Description

This clinical study aims to evaluate the impact of vitamin C supplementation on gut barrier function and systemic inflammation in adults with obesity. The research builds on preclinical findings that suggest vitamin C plays a critical role in maintaining gut integrity and reducing inflammation. Approximately 40% of Americans have suboptimal vitamin C status, with even higher prevalence among individuals with obesity.

The primary hypothesis is that improving vitamin C status through dietary supplementation will reduce intestinal permeability and metabolic endotoxemia. A secondary hypothesis is that vitamin C will also reduce biomarkers of intestinal inflammation and promote favorable changes in gut microbiota composition, including increased production of short-chain fatty acids (SCFAs), which are essential for intestinal health.

This randomized, double-blind, placebo-controlled crossover trial will enroll 34 obese adults (BMI 30-40 kg/m², aged 18-50 years). Participants will complete two 2-week intervention periods separated by a 2-week washout. In one period, they will receive vitamin C (500 mg capsules taken twice daily); in the other, a placebo. During both periods, participants will follow a low-vitamin C diet to minimize variability in circulating vitamin C levels.

Assessments will occur on Days 0, 7, and 14 of each intervention period and include: Anthropometric measurements; Resting blood pressure; Fasting blood samples; and 3-day food records. On Day 14 of each period, participants will: Provide a stool sample and Complete a gut permeability test using a non-digestible sugar probe solution followed by a 24-hour urine collection. After the first intervention period, participants will undergo a 2-week washout before repeating the procedures with the alternate supplement.

Primary Outcome: Intestinal permeability

Secondary Outcomes: Biomarkers of endotoxemia; Gut microbiota composition; Intestinal and circulating inflammation biomarkers; Plasma vitamin C concentrations; Fecal short-chain fatty acids.

Conditions

Adequate Vitamin C Status; Inadequate Vitamin C Status

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: TRIPLE

Study Groups

Inadequate Vitamin C Status

Placebo + Low Vitamin C Diet

Group Type: PLACEBO_COMPARATOR

Placebo + Low Vitamin C Diet

Intervention Type: DIETARY_SUPPLEMENT

Participants will receive a placebo while following a low vitamin C diet to achieve inadequate vitamin C status in a blinded manner. This will be compared to participants receiving a vitamin C supplement while following a low vitamin C diet that is expected to maintain adequate vitamin C status.

Adequate Vitamin C Status

Vitamin C Supplement + Low Vitamin C Diet

Group Type: EXPERIMENTAL

Vitamin C Supplement + Low Vitamin C Diet

Intervention Type: DIETARY_SUPPLEMENT

Participants will receive a vitamin C supplement (1000 mg/d) while following a low vitamin C diet to achieve adequate vitamin C status in a blinded manner. This will be compared to participants receiving a placebo while following a low vitamin C diet that is expected to maintain inadequate vitamin C status.

Interventions

Vitamin C Supplement + Low Vitamin C Diet

Participants will receive a vitamin C supplement (1000 mg/d) while following a low vitamin C diet to achieve adequate vitamin C status in a blinded manner. This will be compared to participants receiving a placebo while following a low vitamin C diet that is expected to maintain inadequate vitamin C status.

Intervention Type: DIETARY_SUPPLEMENT

Placebo + Low Vitamin C Diet

Participants will receive a placebo while following a low vitamin C diet to achieve inadequate vitamin C status in a blinded manner. This will be compared to participants receiving a vitamin C supplement while following a low vitamin C diet that is expected to maintain adequate vitamin C status.

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

• English speaking
• Men and women between 18-50 years of age
• BMI 30-40 kg/m²
• Resting blood pressure <140/90 mm Hg
• No use of multivitamin/vitamin C supplement within past 1-month
• Non-vegetarian/non-vegan
• Willingness to follow a diet low in fruits and vegetables for two, 2-week periods

Exclusion Criteria

• Current smoker or vaper, including tobacco, cannabis, or nicotine products
• Alcohol consumption >2 drinks/day
• Use of antibiotics within past 1-month
• Use of probiotic supplements within past 1-month
• Use of anti-inflammatory drugs within past 1-month
• Individuals with unmanaged or poorly controlled diabetes, dyslipidemia, hypertension
• Known history of bleeding disorders, hemochromatosis, or kidney stones
• For Women: Pregnancy, lactation, or change in birth control within the past 3-months
• Use of certain medications that may interact with vitamin C, including blood thinners, some antiviral drugs (e.g., indinavir), and certain antipsychotic medications (e.g., fluphenazine).

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 50 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Ohio State University

OTHER

Sponsor Role: lead

Responsible Party

Richard Bruno

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Richard Bruno, PhD, RD

Role: PRINCIPAL_INVESTIGATOR

Ohio State University

Locations

The Ohio State University

Columbus, Ohio, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Study Coordinator

Role: CONTACT

NutritionClinicalTrials@osu.edu

614-292-4751

References

Traber MG, Buettner GR, Bruno RS. The relationship between vitamin C status, the gut-liver axis, and metabolic syndrome. Redox Biol. 2019 Feb;21:101091. doi: 10.1016/j.redox.2018.101091. Epub 2018 Dec 26.

Reference Type: BACKGROUND

PMID: 30640128 (View on PubMed)

Other Identifiers

STUDY20251283

Identifier Type: -

Identifier Source: org_study_id