 Acute inflammation induced by surgery and sepsis is complicated by the development of iron-restricted anemia due to the up-regulation of hepcidin. Excess hepcidin causes intracellular sequestration of iron, decreasing its availability for erythropoiesis. Hepcidin might be a potential target to reduce transfusion requirements in surgical and sepsis patients. Vitamin D supplementation might constitute a novel strategy to modulate the hepcidin-ferroportin-iron axis. Up to now, there are no data regarding the possibility that by using vitamin D supplementation in surgical and septic shock patients, the physicians could ameliorate anemia and, hence, reduce transfusion requirements. Aim: to conduct a randomised controlled trial to determine the impact of high-dose vitamin D enteral supplementation on serum hepcidin levels and transfusion requirements after major abdominal surgery and in septic shock patients. 