The history of enteral feeding goes back about 3500 years to the ancient Greeks and Egyptians, who infused nutrient solutions into the rectum to treat various bowel disorders. Over the centuries, experimentation and research have contributed to a greater understanding of nutrient requirements; methods to more accurately access the gastrointestinal tract; development of new materials to use in equipment, tubes, and containers; and the digestion, absorption, and use of macro- and micronutrients. It is notable that while advances were made in one area, progress was being made in another. For example, while enteral access and feeding techniques were being developed, essential amino acids were identified. When new information came together, rapid changes opened up the applications for enteral feeding in new directions, sometimes in unexpected ways such as diets designed for the space program, leading to the use of elemental diets as a therapeutic modality.