Objectives: Three series of studies investigated whether 1) glutamine deficiency occurs in tumor-bearing rats, 2) glutamine supplementation improves protein metabolism during chemotherapy in tumor-bearing rats, and 3) oral glutamine supplement improves systemic immune and gut-barrier function in patients with esophageal cancer receiving radiochemotherapy.
Methods: In the animal studies, AH109A hepatoma cells or Yoshida sarcoma cells were inoculated into male Donryu rats to induce tumors. Glutamine production was measured by U-14C-glutamine infusion and the conversion of arginine to glutamine was measured by infusion of U-14C-arginine. The effect of glutamine on protein metabolism was investigated by 1-14C-leucine infusion. In the clinical study, 13 patients with esophageal cancer were randomized into two groups, control and glutamine supplemented (30 g/d), for 4 wk.
Results: Glutamine levels in plasma and skeletal muscle were decreased in tumor-bearing rats, although glutamine production and the conversion of arginine to glutamine were increased. Glutamine-supplemented total parenteral nutrition reduced whole-body protein breakdown rate during chemotherapy in tumor-bearing rats. Oral supplementation of glutamine to the patients with esophageal cancer enhanced lymphocyte mitogenic function and reduced permeability of the gut during radiochemotherapy.
Conclusions: Glutamine depletion in host tissues occurs in tumor-bearing rats. Glutamine supplementation can attenuate loss of protein in the muscle in tumor-bearing animals and protect immune and gut-barrier function during radiochemotherapy in patients with advanced cancer.