Background: We investigated the effects of pectin, a soluble dietary fiber, on the morphological parameters of the small intestine. In addition, we tested the effects of butyrate enemas on dextran sulfate sodium (DSS)-induced experimental colitis.
Methods: Male Wistar rats were fed an elemental diet containing 2.5% pectin for 14 days, and several parameters were then determined. DSS-induced colitis was evoked by the oral administration of water containing 3% DSS for 10 days. The butyrate enema (3 mL of 100 mmol/L butyrate per day) was begun 7 days before the DSS treatment. Interleukin (IL)-8 secretion in the human intestinal epithelial cell line HT-29 was determined by enzyme-linked immunosorbent assay (ELISA).
Results: Pectin feeding induced a significant increase in the villus height and crypt depth in the small intestine. These effects correlated with a significant increase in plasma enteroglucagon levels. Pretreatment with a butyrate enema significantly blocked the development of DSS-induced experimental colitis. In the in vitro experiment, sodium butyrate dose-dependently inhibited tumor necrosis factor (TNF)-alpha-induced IL-8 secretion in HT-29 cells.
Conclusions: A trophic effect due to dietary fiber was directly observed. The generation of short-chain fatty acids and the induction of enteroglucagon release might play an important role in this process. Butyrate, one of the major metabolites of dietary fiber, exerted a potent anti-inflammatory effect both in vivo and in vitro. Dietary fiber may therefore play important roles in the regulation of normal and pathological conditions in the intestine.