[Lack of stimulation of nitrogen retention and plasma protein synthesis due to increased intake of branched-chain amino acids].

In a randomised study the influence of 3 different amino acids (AA) solutions on nitrogen balance, plasma protein synthesis, and plasma and urine AA pattern was investigated in postoperative (p.o.) cancer patients. The patients in group I received a balanced AA solution designed especially for p.o. patients with 10 percent branched chain amino acids (BCAA), those in group II a solution with 60 percent BCAA and those in group III a solution with 67 percent alanine. All patients received the same amount of nitrogen (0.16 g/kg BW/day) and energy (2.p.o. day: 80 kJ/kg BW/day; 3.-5. p.o. day: 160 kJ/kg BW/day) with a 3:1 ratio of carbohydrate to fat calories. No difference was observed between the three groups for mean daily nitrogen balances, however, the cumulative nitrogen balance of group I (-4.5 +/- 3.6 g) was significantly (p less than 0.05) improved compared to group II (-12.2 +/- 4.2 g). The p.o. decreased concentrations of short-life plasma proteins (prealbumin, transferrin, retinol-binding protein) increased until the end of the study period without any statistic differences between the three groups. On the 2nd p.o. day especially the gluconeogenetic AA were decreased in all patients, but were nearly normal in all patients on the 5th p.o. day. In conclusion the increased administration of BCAA neither improved nitrogen retention nor plasma protein synthesis and does not seem advantageous in the postoperative total parenteral nutrition.