[Elemental, semi-elemental, polymeric diets. Choice, indications, rational use].

In this review paper the main properties of elemental, semi-elemental and polymeric diets utilized in enteral nutrition are compared. The theoretical value of elemental diets (they do not require digestion) is upset by their effects on secretion. Semi-elemental diets are not hyperosmolar and are easily absorbed. Polymeric formulas acan be given in almost all indications of enteral nutrition, and in view of the high cost of elemental and semi-elemental diets, the latter should be reserved to elective indications, notably antigenic arrest of the digestive tract and major nitrogen malabsorption.