Dietary Intervention Trial Design in Patients With an Ileoanal Pouch: Lessons From a Randomized, Double-Blind, Placebo-Controlled Feeding Study.

Purpose: The aims of this study were to assess the effects of a whole diet strategy, a Monash Pouch Diet (MPD), on pouch-related symptoms, inflammation, quality of life, and stool characteristics in a cohort of patients with symptomatic pouches and a history of pouchitis compared with a typical Australian pouch diet. Methods: In this randomized, double-blind, placebo-controlled dietary feeding trial, patients with ileoanal pouches received either a Monash Pouch diet or a typical Australian diet for 7 weeks. Clinical scores (Pouch Disease Activity Index, PDAI), pouch symptoms, tolerability, fecal calprotectin, and quality of life were measured pre- and post-intervention. The primary outcome consisted of the proportion of patients achieving symptomatic remission (clinical PDAI ≤ 2). Results: All patients on the MPD experienced worsening symptoms, and the trial was terminated early. The majority of the participants reported partial adherence (50%-80%) and poor tolerability (median: 40 mm). Quality of life outcomes were highly variable across dietary arms, and fecal indices showed no consistent trends related to diet. Conclusion: This double-blinded, placebo-controlled, dietary feeding trial failed to determine the effect of the Monash Pouch Diet on pouchitis but suggests that the design of dietary trials for pouch patients requires careful consideration.