Enteral and parenteral nutrition refer to several methods to deliver life-sustaining nutrition to patients who cannot or will not feed themselves sufficiently. Enteral nutrition delivers nutrients through a feeding tube to the stomach or small intestine. Parenteral nutrition delivers a nutrient solution directly into the bloodstream through a vein.

Enteral feeding is usually preferred whenever possible for patients who require nutritional support. For instance, enteral nutrition is often used for patients who are not capable of eating (e.g., due to coma, confusion, swallowing difficulties) but whose digestive tracts are intact. Enteral nutrition is associated with fewer complications than parenteral nutrition. Complications may include diarrhea, backflow of food into the lungs (aspiration) and infection.

Unlike parenteral nutrition, which bypasses the digestive system, enteral nutrition allows the stomach and/or intestines to process food normally. A tube is inserted through the nose (less commonly the mouth) and into the stomach or small intestine. In some cases, the tube may be inserted through a small, surgically created opening in the abdomen or by endoscopy. Enteral feeding is usually temporary, with the goal of gradually transitioning the patient to an oral diet.

Parenteral nutrition is typically reserved for a patient whose digestive tract is not working properly or when it must be temporarily kept free of food. For instance, patients develop short bowel syndrome following major bowel surgery may be fed through a catheter inserted into a major or peripheral vein. Some physicians may recommend parenteral nutrition for certain patients with inflammatory bowel disease (usually Crohn’s disease). In some cases, both enteral and parenteral nutrition may be used.