Mechanisms of enteral nutrient-enhanced intestinal adaptation.

The role of enteral nutrients in maintaining small intestinal structure and function is well established. Evidence that enteral nutrients induce intestinal adaptation include the structural and functional gradient along the length of the healthy intestine, the atrophy and functional compromise induced by fasting and parenteral nutrition, and the enhanced adaptive capacity of the distal intestine following partial enterectomy. Key mechanisms contributing to enteral nutrient-induced intestinal adaptation include nonspecific luminal stimulation and that provided by specific nutrients, "functional workload" induced by polymeric nutrients, potential stimulation of pancreaticobiliary secretions, secretion of humoral mediators, and induction of intestinal hyperemia.