Effect of dietary inulin supplementation on inflammation of pouch mucosa in patients with an ileal pouch-anal anastomosis.

Inflammation is a constant finding in the ileal reservoir of patients with an ileal pouch-anal anastomosis and is associated with decreased fecal concentrations of the short chain fatty acid butyrate, increased fecal pH, changes in fecal flora, and increased concentrations of secondary bile acids. In healthy subjects, inulin, a dietary fiber, is fermented to short chain fatty acids and leads to a lower pH and potentially beneficial changes in fecal flora. The aim of the present study was to investigate the effect of enteral supplementation of inulin on inflammation of the ileal reservoir. Twenty patients received 24 g of inulin or placebo daily during three weeks in a randomized, double-blind, crossover design. Stools were analyzed after each test period for pH, short chain fatty acids, microflora, and bile acids. Inflammation was assessed endoscopically, histologically, and clinically. Compared with placebo, three weeks of dietary supplementation with 24 g of inulin increased butyrate concentrations, lowered pH, decreased numbers of Bacteroides fragilis, and diminished concentrations of secondary bile acids in feces. This was endoscopically and histologically accompanied by a reduction of inflammation of the mucosa of the ileal reservoir. Enteral inulin supplementation leads to a decrease of inflammation-associated factors and to a reduction of inflammation of pouch mucosa.