Nutrition and metabolic support in the 21st century.

New approaches to nutritional support are necessary to test therapies that may potentially enhance outcomes. Such approaches include the move to rely on the enteral route for nutrient delivery, the ability to reduce exogenous calories in our nutritional support systems, the need to utilize nutrients for their pharmacological effects, the ability to use growth factors to enhance nutrient efficacy, and the ability to institute nutritional supplementation before elective operations, thus practicing preventative nutrition. Testing these approaches in the years to come should allow us to identify modalities that will permit us to move away from nutritional therapy as a supportive modality and use it as a primary or secondary method of patient care.