Comparison of body protein metabolism during total parenteral nutrition using glucose or glucose and fat as the energy source

Body protein metabolism and plasma amino acids in cirrhosis of the liver. The effect of varying the branched chain amino acid content of intravenous amino acid solutions

Body protein metabolism and plasma amino acids were measured in 37 patients with stable cirrhosis of the liver to assess the effect of disease severity (Child's classification). Thirty two patients underwent a second series of measurements while nutrition was administered intravenously as one of five different infusions. Four infusions were formulations of amino acids with dextrose of varying branched chain amino acid content (100%, 53%, 35% and 16% branched chain to total amino acids). The fifth infusion was dextrose alone. No differences were detected in body protein synthesis and breakdown between patients on the basis of disease severity although some small differences were noted in the plasma amino acids. Infusion of dextrose alone and the 16% BCAA solution led to negative protein balance and a lowering of the plasma branched chain amino acid concentrations. Improved protein balance was observed with 35% BCAA, this solution also lowered the levels of methionine and aromatic amino acids. In those patients given 53% BCAA protein balance was achieved and the plasma branched chain amino acids elevated. Protein balance also occurred with 100% BCAA, in association with marked increases in underlying protein synthesis and breakdown and with this infusion there were marked elevations in the plasma branched chain amino acids and depression of the other plasma amino acids. The increase in protein breakdown with this last formulation was unexpected and may be harmful. On the basis of these findings it is suggested that the composition of the 53% and 35% solutions may be optimal to protein metabolism and manipulation of plasma amino acids in this group of patients.

Effect of branched chain amino acid infusions on body protein metabolism in cirrhosis of liver

Thirty seven patients with established cirrhosis of the liver were subjected to measurement of body protein metabolism using L-(1-14C) labelled leucine as a tracer. The effects of disease severity and those of solutions containing 0%, 16%, 35%, 53%, and 100% branched chain amino acids were evaluated. Significant increases in protein synthesis were noted with solutions containing 35%, 53%, and 100% branched chain amino acids, but in patients receiving 100% branched chain amino acids without additional essential amino acid supplement the increase in synthesis was matched by a significant increase in protein breakdown. Protein balance was thus improved only in patients receiving 35% and 53% branched chain amino acids. It was concluded that the high increase in protein breakdown in patients receiving 100% branched chain amino acids was undesirable, and such a solution should not be recommended for clinical use.