Objective: We aimed to compare the effectiveness of enteral, parenteral and combined enteral-parenteral glutamine supplementations in nutrition of the critical care patients.Material and Method: This is a single-center, prospective, randomized clinical trial. During the 5-day study period, all patients received standard enteral nutrition product and were divided into three groups, including parenteral glutamine (Group I), enteral glutamine (Group II) and enteral+parenteral glutamine (Group III) supplementations. Blood biochemistry, rates of infections, length of stay in intensive care unit and duration of mechanical ventilation were evaluated.Results: Sixty patients were included in this study. There was no statistically significant difference for biochemical values between the different feeding groups. Frequency of infections were ranged as Group II>Group III>Group I and mortality as Group II=III>Group I. Length of stay in intensive care unit and duration of mechanical ventilation were significantly longer in Group II than the others.Conclusion: Although mortality was not significantly different between groups, parenteral glutamine administration causes less stay of intensive care unit and mechanical ventilation days. Further studies are needed with larger randomized controlled groups
