Polémique : l'utilisation des mélanges semi-élémentaires en nutrition entérale

Semi-elemental enteral nutrition mixtures are defined, by comparison with polymeric mixtures, by their content of small peptides and/or hydrolyzed protein (vs. intact protein), and a high proportion of medium-chain triglycerides (instead of long-chain triglycerides). The easier digestion is presumed to favor intestinal absorption and improve the efficacy of enteral nutrition in clinical settings when protein hydrolysis is impaired: exocrine pancreatic insufficiency, acute pancreatitis, enteral nutrition administered into a jejunum, duodeno-pancreatectomy, interruption of biliary flow, short bowel syndrome. Even though a few small randomized trials suggest satisfactory tolerance of semi-elemental mixtures in acute pancreatitis, and improved nitrogen bioavailability in jejunal nutrition or in short bowel syndrome, hard evidence and controlled trials are scarce. The use of semi-elemental mixtures with low long-chain triglycerides to reduce lymph secretion is warranted in chylothorax or chylous ascites. There is, however, no strong evidence for an improved trophic or anti-inflammatory effect of semi-elemental, vs. polymeric mixtures in chronic inflammatory bowel disease. The higher osmolarity of semi-elemental mixtures exposes to a higher risk of poor gastrointestinal tolerance, and the nature of nitrogen supply, to a risk of impaired net protein accretion. In summary, although semi-elemental mixtures emerged over 30 years ago, there is no decisive proof of their superiority over polymeric mixtures, so the prescription of semi-elemental mixtures should probably be restricted to specific clinical settings such as chylous ascites, and in some cases of severe malabsorption, or as a second line treatment when polymeric mixtures fail. Yet such indications only rely on expert opinions, rather than strong evidence.