Branched chain amino acid enriched elemental diets support hepatic protein synthesis in injured rats

Recent evidence has suggested that intravenous administration of amino acid formulas enriched with branched chain amino acids can reduce nitrogen loss after injury and support protein synthesis. However, the use of a comparable enteral product to feed injured animals has received little attention. In this study we report the results of a new experimental amino acid formula that contains 44% branched chain amino acids as a component of a complete elemental diet to spare body protein and affect protein kinetics in injured and infected rats. After non-sterile, bilateral hindlimb fractures, rats received one of two isovolemic, isocaloric diets that differed only in the amino acid formula. One of the diets contained 15.4% branched chain amino acids while the other contained 44%. During the three day feeding period, changes in body weight, cumulative nitrogen balance and serum transferrin concentrations were similar between the two groups. However, rates of plasma leucine oxidation were increased 174% (p<0.05) by the branched chain amino acid enriched feeding. In addition, liver protein synthesis was also significantly increased with the new amino acid formula. The enhancement of protein synthesis, especially in the liver, suggests that enteral administration of a new amino acid formula enriched with branched chain amino acids results in significant metabolic differences and may offer a potential benefit in supporting protein synthesis necessary for recovery.