Glutamine supplementation will be dosed at 0.5 g/kg satisfactory body weight (SBW)/day divided every 8 hours, starting 6 hours post-operatively and continued for 5 days. The dose of 0.5 g/kg SBW/day was effective in clinical studies using enteral glutamine in critically ill and/or burn injured and major trauma patients. The glutamine supplementation or placebo will be delivered via naso- or oro-gastric feeding tube after confirmation of placement by chest X-ray. For participants who are extubated prior to 5 days, enteral glutamine will be given by mouth for the duration of the 5 day period. Glutamine and placebo will be mixed in orange juice to maintain blinding.