BackgroundThe purpose of this study is to investigate the effects of intraoperative infusion of branched-chain amino acids (BCAA) in patients undergoing gastrointestinal tumor surgery.MethodsSixty-one patients with gastrointestinal tumors undergoing gastrointestinal surgery were enrolled and randomly assigned to receive an intraoperative infusion of 3-compound BCAA solution (N = 20), amino acids (AA) solution (N = 21), or normal saline (NS) (N = 20). Nasopharyngeal temperature, blood glucose (BG), plasma insulin, and blood free fatty acids (FFA) concentrations were measured at 30 min before and 10 min after induction (T0,T1), 30 min and 2 h after skin incision (T2,T3), and 1 h after tracheal extubation (T4). Intensity of shivering and pain was accessed at 1 h after extubation.ResultsThe temperature in the BCAA and AA group was significantly higher than that in the NS group at T4 (P = 0.014 and 0.033). The incidence of shivering in the BCAA and AA group was significantly lower than in the NS group (P = 0.027 and 0.012). BG increased in AA group at T3 and T4 (P = 0.001 and 0.045). The plasma insulin concentration increased in the BCAA and AA group from T1 to T3. The plasma FFA concentrations in the BCAA group were lower than in the AA and NS group from T2 to T4.ConclusionsIntraoperative BCAA and AA infusion alleviated postoperative hypothermia and shivering. BCAA infusion also inhibited fat mobilization, without adversely affecting blood glucose.Trial registrationChiCTR-TRC-14004668Electronic supplementary materialThe online version of this article (doi:10.1186/s12957-015-0751-y) contains supplementary material, which is available to authorized users.