Increased Ureagenesis and Impaired Nitrogen Use during Infusion of a Synthetic Amino Acid Formula: A Controlled Trial

In a controlled trial conducted to assess the biologic value of High Nitrogen Vivonex, we compared this“elemental”diet with predigested protein — Product MJ7041 — and with solid food during eight-day balance periods. Each formula was evaluated in three patients with malabsorption and one without it, by measuring apparent absorption of nitrogen and energy, nitrogen balance, and blood and urinary urea nitrogen. Overall energy and nitrogen absorption in the patients with malabsorption was better with either special diet than with solid food; net intestinal uptake of Vivonex tended to be higher but not consistently so in all patients. However, nitrogen balance differed consistently during the three diets; with solid food and MJ7041, retention of absorbed nitrogen was respectively, nine and 16 times greater than with Vivonex. Moreover, institution of each Vivonex period led to a prompt increase in urea nitrogen — a trend quickly reversed by the alternative diets. Although the mechanism for the impairment of nitrogen use caused by High Nitrogen Vivonex is unknown, its low biologic value and tendency to cause azotemia should be kept in mind. (N Engl J Med. 1982; 306:1013–8.) THE group of liquid diets termed“elemental”has been widely used in the nutritional support of undernourished patients with intestinal disease.^{1 2 3 4 5 6 7} Generally, the solutions are low in fat and contain nitrogen in the form of hydrolyzed naturally occurring proteins or synthetic amino acids. Unlike comparable parenteral solutions, the elemental diets contain sufficient amounts of known essential and recommended nutrients. The formulas therefore require no supplemental trace elements or essential fatty acids and thus should produce growth of new protein-containing tissues and weight gain. We were therefore surprised when balance studies conducted in a patient with malabsorption during infusion of the. . .