Background
Artificial nutrition support has evolved into a primary therapeutic intervention to prevent metabolic deterioration and loss of lean body mass with the aim to improve the outcome of critically ill patients. Apart from the timing of initiation and the targeted amount of macronutrients, the route of delivery is viewed as an important determinant of the effect of the nutritional intervention. Using the enteral route is considered to be more physiologic, providing nutritional and various non-nutritional benefits including maintenance of structural and functional gut integrity as well as preserving intestinal microbial diversity [1–3]. The disadvantage of enteral nutrition (EN) is related to a potential lower nutritional adequacy particularly in the acute disease phase and in the presence of gastrointestinal dysfunction [4, 5]. In contrast, parenteral nutrition (PN) may better secure the intended nutritional intake but is associated with more infectious complications, most likely due to hyper alimentation and hyperglycemia, as consistently shown in earlier meta-analyses [6–9]. These clinical data have translated into widespread consensus among current international guideline recommendations [10–13] and expert opinions [14, 15] that the enteral route is preferred in critically ill patients without a contraindication to EN.