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Protocols

Category: Protocols (Poster Session)

Protocols (Poster Session)

(P42-04-26) Regulation of Gut Barrier Function by Inadequate Vitamin C Status in Adults With Obesity: Protocol of a Randomized, Double-Blind, Placebo-Controlled Crossover Trial

Monday, July 27, 2026
9:30 AM - 10:30 AM ET
Location: Poster Board D-4
Disclosure(s):
Jillian T. Pierson, M.S, R.D: No relevant financial relationship(s) with ineligible companies to disclose.


Objectives: Adults with obesity often have low vitamin C status and increased intestinal permeability, which may contribute to metabolic inflammation and endotoxin exposure. Vitamin C supports antioxidant defense and epithelial integrity, but its gut health-promoting activities in humans have not been examined. Here, we describe the protocol, rationale, methodology, and expected outcomes of a planned randomized, double-blind, placebo-controlled crossover study. We will test the hypothesis that inadequate vitamin C status impairs intestinal permeability and increases metabolic endotoxemia-associated inflammation in adults with obesity.

Methods: Thirty-four adults with obesity (body mass index 30–45 kg/m²) will complete two two-week intervention periods of vitamin C (500 mg twice daily) and placebo in a randomized, double-blind crossover trial, separated by a 2-week washout. Data will be collected at baseline and on days 7 and 14 of each period. Participants will follow a low–vitamin C diet to minimize dietary variability. Adherence will be assessed by capsule counts and corroborated by measures of plasma vitamin C. The primary outcome is intestinal permeability assessed from the urinary excretion of non-digestible sugar probes ingested at the end of each study arm. Secondary outcomes include plasma markers of endotoxin exposure and inflammation (lipopolysaccharide-binding protein, soluble CD14, C-reactive protein, interleukin-6, tumor necrosis factor-α), inflammatory gene expression in peripheral blood mononuclear cells (toll-like receptor 4 pathway targets), and fecal concentrations of short-chain fatty acids, myeloperoxidase, and calprotectin. Data will be analyzed using paired t-tests for crossover comparisons or linear mixed models for repeated measures.

Results: To date, 15 participants (6 men, 9 women) have been enrolled and randomized; 4 completed, 3 were lost to follow-up, and 8 are in progress. No serious adverse events have been reported.

Conclusions: This trial will provide novel evidence on whether gut barrier function and endotoxemia-associated inflammation is regulated in a vitamin C-dependent manner and will inform feasibility and design considerations for longer-duration interventions.

Funding Sources: No external funding