Objective To investigate the effects of enteral nutrition added with glutamine on the incidences of gastrointestinal complications,intestinal mucosal barrier function and inflammatory responses in patients with acute severe traumatic brain injury (sTBI).Methods A prospective case control study was made on 107 patients with sTBI hospitalized from January 2016 to June 2017.The patients were divided into experimental group added with glutamine (n =54) and control group without glutamine (n =53) according to the random number table.The general data of the patients were recorded.After treatment,the incidences of gastrointestinal complications in both groups were compared.The serum levels of intestinal mucosal barrier function indices,namely,diamine oxidase (DAO),Dlactate acid,and intestinal fat acid binding protein (I-FABP) were evaluated by enzymology spectrophotometer method.Meanwhile,the serum levels of C-reactive protein (CRP),tumor necrosis factor-α (TNF-α),and interleukin-6 (IL-6) were also tested with enzyme-linked immunosorbent assay (ELISA).Glasgow coma scale (GCS),acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ),and hospital stay in both groups were compared.Results The two group were comparable with respect to gender,age,injury reasons,body mass index,preoperative GCS,preoperative APACHE Ⅱ,injury type and injury time (P ＞ 0.05).The experimental group had lower incidences of stress ulcer,gastric retention and diarrhea compared with the control group 14 days after treatment (P ＜ 0.05).Within 14 days after treatment,the serum levels of DAO,D-lactate acid and I-FABP were significantly decreased in the experimental group at days 7 and 14 after treatment (P ＜ 0.05).The serum levels of CRP,TNF-α and IL-6 in the experimental group were significantly decreased after treatment (P ＜ 0.05).The experimental group had better prognosis compared with the control group (P ＜ 0.05),with higher GCS scores [(9.3 ± 0.7) points vs.(8.2 ± 0.7) points],lower APACHE Ⅱ scores [(15.3 ± 1.1) points vs.(17.7 ± 1.2) points] at day 14,and shorter hospital stay [(19.1 ± 2.2) days vs.(25.3 ± 2.4) days] (P ＜ 0.01).Conclusions Enteral nutrition added with glutamine can effectively reduce the incidence of gastrointestinal complications,as well as alleviate the intestinal mucosal barrier function damage and the inflammatory responses at early stage after sTBI,which possibly improves prognosis.