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During the congress, E-Posters will be accessible to all participants on the congress website 24/7, as well as in the E-poster stations in the congress center.
Preparing your E-Poster
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E-Poster Submission Deadline
Please prepare and upload your E-Poster no later than March 14, 2026 11.59PM CET. After this date, you will no longer be able to prepare and upload your E-poster and it will not be displayed and accessible on the congress website.
Please follow the instructions below to input your abstract title.
Abstract titles should be brief and reflect the content of the abstract.
Vitamin C is a small, water-soluble molecule that is renally cleared; therefore, an inverse or no association between kidney function and plasma vitamin C would be expected. However, in multiple cohorts of kidney transplant recipients (KTR), we observed a positive association between eGFR and plasma vitamin C. We hypothesize that reduced kidney function increases circulating benzoic acid, a commonly used food preservative. Benzoic acid can react with vitamin C to produce the toxic molecule benzene. Animal experiments suggest that this reaction could occur in vivo, and if so, benzene exposure might contribute to uremic symptoms and malignancy risk in CKD. For the first time in a human model, we aim to evaluate the possibility of this reaction in vivo by assessing whether reducing dietary benzoate increases plasma vitamin C and decreases benzene exposure in KTR.
In this randomized crossover trial, we will include adult KTRs (≥18 years), who are at least one year post-transplant. We will evaluate two 12-week intervention periods in random order: (A) a benzoic acid-free diet; and (B) a usual diet. The benzoic acid-free diet will be developed with the nutrition team using published templates (e.g., for orofacial granulomatosis) and tailored to maintain stable total vitamin C intake. No washout period is planned, and assessments will occur within 24 hours after each period. The primary outcome will be plasma vitamin C concentration, and the secondary outcome will be urinary trans-trans-muconic acid (ttMA) as a benzene-exposure biomarker. We plan to include 78 participants, which will provide 80% power (α=0.05) to detect a within-person difference of 7 μmol/L in plasma vitamin C (SD for repeated measures 21.7). We will perform an intention-to-treat analysis using linear mixed-effects models, which will include participant as a random intercept and fixed effects for treatment, period, and sequence.
The study is powered to detect a clinically meaningful increase in plasma vitamin C after the removal of benzoic acid intake. We expect that a benzoic acid-free diet will raise plasma vitamin C levels and lower ttMA, with effect sizes influenced by kidney function. Adherence metrics, dietary consistency, and biomarker variability will be reported to provide context for treatment effects.
This randomized crossover trial will provide the first prospective human test of a benzoate–ascorbate–benzene pathway in KTR. If benzoate restriction raises plasma vitamin C while reducing benzene exposure, the results will support immediately actionable dietary guidance for patients with reduced kidney function, inform preservative policies relevant to CKD/KTR populations, and refine the debate on vitamin C supplementation after transplantation.
