Objective To investigate the effects of enteral nutrition support with different doses of glutamine on nutritional status and gastrointestinal function in elderly critically ill patients.Methods Totally 90 critically ill patients were randomly divided into three group:the control group without glutamine (group A),enteral nutrition with low glutamine [0.3 g/(kg· d)] (group B),and high glutamine [0.6 g/(kg· d)] groups (group C).Fasting blood samples were collected on days 1,7,and 14 after the initiation of study,and then the indicators including serum diamine oxidase,glutamine,transferin (TF),prealbumin (PA),hemoglobin (HGB),albunin,and nitrogen balance were determined.In addition,the gastrointestinal complications including bloating,diarrhea,and gastric retention were recorded.Results On the 7th and 14th days,the serum glutamine levels in groups B and C were (1 886.8 ±420.5),(2 228.6 ±440.2) μg/L;(1 889.6 ± 436.1),(2 174.3 ± 440.8) μg/L,respectively,which were significantly higher than those in group A [(1 612.0 ±493.5),(1 869.7 ±559.8) μg/L] (P =0.027,P =0.008).The serum diamine oxidase levels were also significantly lower in group B [(2 310 ± 1 271),(1 602.5 ± 1 137.9) U/L] and group C [(2 076.3 ±567),(1 586.3 ±530.9) U/L] than in group A [(3 250 ±923),(2 476 ±862) U/L] (P =0.000,P =0.000).The serum TF and PA levels were significantly increased on the 7th day (P =0.023,P =0.047),and the HGB was significantly higher on 14th day (P =0.003),The number of patients who had undergone successful implementation of enteral nutrition were 4 and 3 in groups B and C,and the number of patients who had achieved the target volume of enterral nutrition was 25 and 27 in groups B and C,which were significantly larger than those in group A (12 and 13,respectively) (P =0.008,P =0.000).The gastrointestinal complication was also significantly decreased after the administration of enterral nutrition with glutamine.Conclusions Enteral nutrition with glutamine can improve intestinal mueosa barrier and nutritional status in elderly critically ill patients.Thus,it helps to reduce gastrointestinal complications and transition time of total enteral nutrition.