Enteral Nutrition in Acute Pancreatitis

The purpose of this prospective randomised clinical trial is to compare beneficial and harmful effects of the use enteral nutrition versus a nil-by-mouth and intravenous fluid replacement principle of treatment in patients with moderate to severe acute pancreatitis (AP). The hypothesis: * enteral nutrition is no significantly better compared with the nil-by-mouth principle regarding mortality, incidence of local and systemic complications, length of hospital stay, and intensity of the inflammatory response in patients with moderate to severe AP * enteral nutrition has the same safety as nil-by-mouth principle in patients with moderate to severe AP