Randomized, controlled study evaluating effects of branched chain amino acids and alpha-ketoisocaproate on protein metabolism after surgery

Abstract

Abstract The effect of nutritional supplementation with branched chain amino acids or the ketoacid α-ketoisocaproate on protein metabolism after surgery was studied in 24 patients with gastrointestinal cancer. They were randomized to receive one of three nutritional regimens. All patients received a balanced amino acid solution and group 1 (n = 8) received no further supplements, group 2 (n = 8) received supplementation with α-ketoisocaproate (17 g day−1) and group 3 (n = 8) received a branched chain solution including leucine, isoleucine and valine, corresponding to 3·3 g nitrogen day−1. Plasma albumin, prealbumin, fibronectin and serum urea concentrations, nitrogen balance and 3-methylhistidine release from the leg and its excretion in the urine were measured. Albumin and prealbumin concentrations fell after surgery in all groups, and fibronectin levels fell in group 2 (P < 0·001). In group 2 there was also a significant increase in serum urea concentration after operation (P < 0·05). Cumulative nitrogen balance after 3 days was −5·6 g (group 1), −3·8 g.(group 2) and −1·7 g (group 3). The release of 3-methylhistidine (nmol 100 g−1 min−1) from the leg after operation, following an overnight fast, was −0·42 (group 1), −0·51 (group 2) and -0·66 (group 3). During infusion the release was −0·56, −0·99 and −0·81, respectively. A balanced amino acid solution with an adequate energy supply has an optimal nitrogen-sparing effect. Branched chain amino acids or α-ketoisocaproate did not improve nitrogen balance or reduce protein degradation.