Malnutrition is an important cause of mortality and morbidity in critically ill patients. Moreover, malnutrition leads to increased apoptosis leading to secondary immune deficiency. Nutritional support is therefore an important aspect of patient care in critically ill patients. Although total parenteral nutrition (TPN) provides sufficient energy and protein requirement to critically ill patients, it increases the risk of infection by inducing apoptosis in the intestinal epithelial cells resulting in the loss of mucosal epithelial barrier function. However, early parenteral nutritional support inhibits autophagy in critically ill patients, leading to suppression of natural immunity, infection development, and increased organ dysfunction. Autophagy is an important repair process in the recovery of organ dysfunction caused by critical disease. Therefore, the absence of parenteral nutritional support in the acute phase of critical disease stimulates autophagy and accelerates recovery. Even though it is thought that fasting-activated autophagy may have positive effects on critical illness, early trophic/hypocaloric enteral nutrition support should be initiated in patients at high risk of malnutrition.

Keywords: Apoptosis, autophagy, enteral nutrition, inflammation, malnutrition