Incretins and enteral nutrition

In contrast to parenteral nutrition, enteral nutrition induces the secretion of gastro-intestinal hormones including incretines. Glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) potentiate insulin production but also inhibit glucagon secretion. GIP and GLP-1 secretion depends upon nutriment absorption and especially lipids that highly stimulate their production. However, their action is not limited to insulin secretion. GIP and GLP-1 also improve sensitivity to insulin. By stimulating adipocytal lipogenesis, GIP appears to be a real entero-adipocytal integrative system that improves anabolism. GIP and GLP-1 inhibit acid gastric secretion, slow down transit by altering intestinal motility, and improve mesentric vascularisation and digestive trophicity. GLP-1, the hormone of ileal break, slows down gastric emptying, which decreases carbohydrate absorption, limiting their impact on blood glucose level. If considering the properties of the hormones which secretion is mediated by incretins, enteral nutrition may improve blood glucose balance. Improvement also occurs when enteral nutrition is associated with parenteral nutrition. Favourable impact of enteral nutrition on intestinal inflammation, vascularisation, and healing process may be related to these hormonal effects, most probably enhanced when nutrition is administered for prolonged periods. Finally, enteral nutrition impact may also depend on its site of administration.