Effects Of Glutamine Supplementation Research Articles

Glutamine prevents high-fat diet-induced hepatic lipid accumulation in mice by modulating lipolysis and oxidative stress

Metabolic-associated fatty liver disease (MAFLD) is related to metabolic dysfunction and is characterized by excess fat storage in the liver. Several studies have indicated that glutamine could be closely associated with lipid metabolism disturbances because of its important role in intermediary metabolism. However, the effect of glutamine supplementation on MAFLD progression remains unclear. Here, we used a high-fat diet (HFD)-induced MAFLD C57BL/6 mouse model, and glutamine was supplied in the drinking water at different time points for MAFLD prevention and reversal studies. A MAFLD prevention study was performed by feeding mice an HFD concomitant with 4% glutamine treatment for 24 weeks, whereas the MAFLD reversal study was performed based on 4% glutamine treatment for 13 weeks after feeding mice an HFD for 10 weeks. In the prevention study, glutamine treatment ameliorated serum lipid storage, hepatic lipid injury, and oxidative stress in HFD-induced obese mice, although glutamine supplementation did not affect body weight, glucose homeostasis, energy expenditure, and mitochondrial function. In the MAFLD reversal study, there were no noticeable changes in the basic physiological phenotype and hepatic lipid metabolism. In summary, glutamine might prevent, but not reverse, HFD-induced MAFLD in mice, suggesting that a cautious attitude is required regarding its use for MAFLD treatment.

The Effects of Glutamine Supplementation on Liver Inflammatory Response and Protein Metabolism in Muscle of Lipopolysaccharide-Challenged Broilers

The aim of our present study was to investigate the effects of Gln supplementation on liver inflammatory responses as well as protein synthesis and degradation in the muscle of LPS-challenged broilers. A total of 120 one-day-old male broiler chickens (Arbor Acres Plus) were randomly arranged in a 2 × 2 factorial design with five replicates per treatment and six broilers per replicate, containing two main factors: immune challenge (injected with LPS in a dose of 0 or 500 µg/kg of body weight) and dietary treatments (supplemented with 1.22% alanine or 1% Gln). After feeding with an alanine or Gln diet for 15 days, broilers were administrated an LPS or a saline injection at 16 and 21 days. The results showed that Gln supplementation alleviated the increased mRNA expressions of interleukin-6, interleukin-1β, and tumor necrosis factor-α induced by LPS in liver. Moreover, the increased activity of aspartate aminotransferase combined with the decreased expression of glutaminase in muscle were observed following Gln addition. In addition, in comparison with the saline treatment, LPS challenge altered the signaling molecules’ mRNA expressions associated with protein synthesis and degradation. However, Gln supplementation reversed the negative effects on protein synthesis and degradation in muscle of LPS-challenged broilers. Taken together, Gln supplementation had beneficial effects: alleviating inflammatory responses, promoting protein synthesis, and inhibiting protein degradation of LPS-challenged broilers.

Effect of glutamine supplementation in elderly people with emphasis on sarcopenia, immunity and hypertrophy: a concise systematic review

Currently, the aging of the population is no longer a forgotten subject for health professionals in Brazil. This is due to the decrease in the birth rate in the country and the improvement in quality of life, this first factor was boosted after the ease of access to information on contraceptive methods and their distribution by the health system. As a result, the Nutrition area has been studying more diligently ways to provide elderly people with methods that contribute to a more comfortable, healthy, and long-lasting life. The nutritionist is essential to identify the deficits and disharmonization of the body of the elderly caused naturally over the years in people's lives, such as loss of muscle mass, and lack of nutrients, among others. Given this scenario, this work will be focused on showing that the use of oral Glutamine supplementation contributes to the gain of muscle mass in the elderly since this natural amino acid present mainly in the muscle tissue of the human body is greatly reduced due to loss of mass skin and body weight gain caused by the slow metabolism found in older people. In this way, supplementation along with a well-designed nutritional table and an exercise routine will promote less chance of injury to the elderly due to a lack of nutrients and greater physical resistance. To reinforce and prove this study, we will use the literature review method distributed in topics.

Effects of Glutamine Supplementation on the Gut Health and Immune Function of Athletes

Effects of Glutamine Supplementation on the Gut Health and Immune Function of Athletes

The effects of glutamine supplementation on markers of apoptosis and autophagy in sickle cell disease peripheral blood mononuclear cells

ObjectivesL-Glutamine was FDA-approved for sickle cell disease (SCD) in 2017, yet the mechanism(s)-of-action are poorly understood. This study investigates the potential activation of autophagy as a previously unexplored mechanism-of-benefit. DesignProspective, open-label, 8-week, phase-2 trial of oral L-glutamine (10 g TID) in patients with SCD at risk for pulmonary hypertension identified by Doppler-echocardiography by an elevated tricuspid-regurgitant-jet-velocity (TRV)≥ 2.5 m/s. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples taken from SCD patients at baseline, two, four, six and eight weeks of glutamine therapy, and from controls at baseline; BAX (pro-apoptotic marker) and LC3-II/LC3-I (autophagy marker) were measured via western blot analysis to assess apoptosis and autophagy respectively. SettingComprehensive SCD Center in Oakland, California. ResultsPatients with SCD (n = 8) had a mean age of 44 ± 16, 50% were male; 63% Hb-SS, and mean TRV= 3.1 ± 0.7 m/s. Controls’ mean age (n = 5) was 32 ± 12% and 57% were male; all were Hb-AA with a mean TRV= 1.8 ± 0.6. At baseline, SCD-PBMCs had 2-times higher levels of BAX and LC3-I versus controls (both p = 0.03). Levels of BAX expression increased by 300% after 8-weeks of glutamine supplementation (p = 0.005); LC3-I protein levels decreased while LC3-II levels increased by 70%, giving a significant increase in the LC3-II/LC3-I ratio (p = 0.02). ConclusionPBMCs from glutamine-supplemented SCD patients have upregulated apoptotic and autophagy proteins. The parallel increase in BAX and the LC3-II / LC3-I ratio with glutamine supplementation suggest a possible role of autophagic cell death. The increase in apoptotic markers provide insight into a possible mechanism used by peripheral PBMCs during glutamine supplementation in patients with SCD.

Glutamine supplementation improves contractile function of regenerating soleus muscles from rats.

This study evaluated the effects of glutamine supplementation immediately after freezing injury on morphological and contractile function of regenerating soleus muscles from rats. Young male Wistar rats were subjected to cryolesion of soleus muscles, and immediately after received a daily supplementation of glutamine (1g/kg/day). The muscles were evaluated on post-injury days 3 and 10. Glutamine-supplemented injured muscles had a lower number of CD11b positive immune cells and higher mRNA levels of IL-4 compared to those from the cryolesioned muscles analyzed on post-injury day 3. The mRNA and protein expression levels of the myogenic transcription factor MyoD were also higher in glutamine-supplemented injured muscles than in injured muscles examined on post-cryolesion day 3. In addition, glutamine-supplemented injured muscles had a higher size of their regenerating myofibers, attenuated decline in maximum tetanic strength and improved fatigue resistance compared to those from injured muscles evaluated on post-cryolesion day 10. No effect was observed in uninjured muscles supplemented with glutamine. Our results suggest that glutamine supplementation improves the resolution of inflammation, as well as the size and functional recovery of regenerating myofibers from soleus muscles by accelerating the up-regulation of IL-4 and MyoD expression. Future non-pharmacological rehabilitation studies are warranted to investigate the effect of glutamine supplementation on the outcome of injured skeletal muscles.

Effect of Glutamine Supplementation on Muscular Damage Biomarkers in Professional Basketball Players.

Scientific evidence supports the role of L-glutamine in improving immune function. This could suggest a possible role of L-glutamine in recovery after intense exercise. To this end, the present report aimed to study if oral L-glutamine supplementation could attenuate muscle damage in a group of players of a mainly eccentric sport discipline such as basketball. Participants (n = 12) were supplemented with 6 g/day of glutamine (G group) or placebo (P group) for 40 days in a crossover study design (20 days with glutamine + 20 days with placebo and vice versa). Blood samples were obtained at the beginning and at the end of each period and markers from exercise-induced muscle damage were determined. The glutamine supplemented group displayed significantly low values of aspartate transaminase, creatine kinase and myoglobin in blood, suggesting less muscle damage compared to the placebo. In addition, adrenocorticotropic hormone levels were lower in the glutamine supplemented group than in the placebo. As a result, the circulating cortisol levels did not increase at the end of the study in the glutamine supplemented group. Altogether, the results indicate that glutamine could help attenuate exercise-induced muscle damage in sport disciplines with predominantly eccentric actions.

Effect of glutamine supplementation on cardiometabolic risk factors and inflammatory markers: a systematic review and meta-analysis

BackgroundEvidence exists that glutamine plays multiple roles in glucose metabolism, insulin sensitivity, and anti-inflammatory effects. This systematic review and meta-analysis of controlled trials aimed to assess the effect of glutamine supplementation on cardio-metabolic risk factors and inflammatory markers.MethodsThe processes of systematic reviews and meta-analyses were performed according to the PRISMA checklist. PubMed, Web of Sciences, Cochrane library, and Scopus databases were search for relevant studies without time or language restrictions up to December 30, 2020. All randomized clinical trials which assessed the effect of glutamine supplementation on “glycemic indices”, “level of triglyceride, “and “inflammatory markers” were included in the study. The effect of glutamine supplementation on cardio-metabolic risk factors and inflammatory markers was assessed using a standardized mean difference (SMD) and 95% confidence interval (CI). Heterogeneity between among studies was assessed using Cochran Q-statistic and I-square. Random/fixed-effects meta-analysis method was used to estimate the pooled SMD. The risk of bias for the included trials was evaluated using the Cochrane quality assessment tool.ResultsIn total, 12 studies that assessed the effect of glutamine supplementation on cardio-metabolic risk factors were included in the study. Meta-analysis showed that glutamine supplementation significantly decreased significantly serum levels of FPG [SMD: − 0.73, 95% CI − 1.35, − 0.11, I2: 84.1%] and CRP [SMD: − 0.58, 95% CI − 0.1, − 0.17, I2: 0%]. The effect of glutamine supplementation on other cardiometabolic risk factors was not statistically significant (P > 0.05).ConclusionOur findings showed that glutamine supplementation might have a positive effect on FPG and CRP; both of which are crucial as cardio-metabolic risk factors. However, supplementation had no significant effect on other cardio-metabolic risk factors.

Effects of glutamine supplementation on critically ill patients: Focus on efficacy and safety. An overview of systematic reviews.

The aim of this overview of systematic reviews was to synthesize, appraise, and present all systematic review (SR) evidence on the clinical efficacy of glutamine administration to severely ill patients. Medline, Scopus, the Cochrane Library, and Prospero were searched up to March 2020. Systematic reviews and meta-analyses of randomized controlled trials published in English, comparing immunomodulating diets-containing exclusively glutamine-with standard diets for critically ill adult patients were selected. Data were collected from each selected systematic review and all available primary studies. The primary outcome was overall mortality; secondary outcomes were rate of infectious complications, hospital and intensive care unit (ICU) length of stay (LOS). Seventeen SRs were eligible for inclusion. Of the SRs, 16 included meta-analyses with moderate degree of overlap (corrected covered area=10%). These included 117 randomized controlled trials with 9933 patients. Glutamine supplementation was not associated with overall mortality and ICU LOS. However, it may reduce the rate of infectious complications overall (N=3666, risk ratio, 0.82; 95% confidence interval [CI], 0.73-0.92; I2=33%: low quality of evidence). LOS was limited with the supplementation of glutamine (N=4353 weighted mean difference, -2.90; 95% CI, -3.66 to -2.15; I2=81%: very low quality of evidence), but this effect was diminished when only studies with low risk for bias were synthesized. Glutamine could demonstrate a beneficial role in critical care patients of diminishing the rate of infectious complications and hospital and ICU LOS. However, future studies with better quality would confirm this finding.

The Effect of Glutamine Supplementation on Ileum Histopathology of Rats with Acute and Chronic EPEC-Induced Diarrhea

BACKGROUND: Glutamine is a non-essential amino acid as the main fuel in the gastrointestinal mucosa. By its various gastrointestinal functions, glutamine is thought to increase the protection of the intestinal mucosa against local or systemic injury from diarrhea. 
 AIM: This study aims to determine the relationship between glutamine supplementation and ileum histopathology in rats with acute and chronic diarrhea induced by EPEC.
 MATERIAL AND METHODS: The research was conducted in an experimental laboratory with a randomized posttest-only control group design. A total of 30 Rattus novergicus strain Wistar were divided into 5 groups. The treatment group was induced to have diarrhea using EPEC at a dose of 108 CFU/ml, after each group diagnosed by acute and chronic diarrhea, followed by glutamine supplementation at a dose of 810 mg/200 g for 14 days. The intestinal histopathology of each group was assessed and their levels of inflammation classified based on the Barthel-Mandja inflammatory score.
 RESULT: The result showed that significant differences in inflammation levels between the negative control group, acute diarrhea group, chronic diarrhea group, acute diarrhea group with glutamine, and chronic diarrhea group with glutamine were found (p<0.05). The highest level of inflammation was found in the acute diarrhea group.
 CONCLUSION: This study concluded that glutamine supplementation has an effect on the ileum histopathology of rats with acute and chronic diarrhea.
 Keywords: Enteropathogenic E. Coli, Glutamine, gastrointestinal tract, pathology, ileum.

The effect of glutamine on Dehydroepiandrosterone-induced polycystic ovary syndrome rats

BackgroundPrevious studies have shown that chronic inflammation and oxidative stress may play an important role in the pathophysiology of polycystic ovary syndrome (PCOS), and glutamine (Gln) have showed the anti-inflammatory and antioxidant properties. So the aim of this study is to investigate the effect of glutamine supplementation on PCOS rats.MethodsFemale Sprague–Dawley rats were randomly assigned into four groups (n = 10 /group), control group, PCOS group, PCOS+ 0.5 g/kg Gln group and PCOS+ 1.0 g/kg Gln group. All the PCOS rats were administrated with 6 mg/100 g dehydroepiandrosterone (DHEA) for 20 consecutive days, all the PCOS+Gln groups were intraperitoneal injected glutamine twice in the next morning after the last DHEA injection. All the samples were collected 12 h after the last administration. Ovarian histological examinations were analyzed and the concentration of serum hormone, inflammatory and oxidative stress factors were measured.ResultsThere was no obvious ovarian histological change among the PCOS group and PCOS+Gln groups. All the detected inflammation factors [C-reactive protein, interleukin (IL)-6, IL-18, tumor necrosis factor] showed significantly higher in all the PCOS groups compared to the control group (P < 0.01), and were significantly decreased with the supplementation of 0.5 g/kg glutamine (P < 0.01). Concentrations of superoxide dismutase were significantly lower in all the PCOS groups (P < 0.01) compared to the control group, and increased significantly with the supplementation of 0.5 g/kg glutamine (P < 0.01). Serum concentrations of malondialdehyde, nitric oxide synthase and nitric oxide were significantly higher in PCOS group (P < 0.01) compared with the control group, and significantly decreased to the comparative levels of control group with supplementation of 0.5 g/kg glutamine (P < 0.01).ConclusionThere is low-grade inflammation and oxidative stress in DHEA-induced PCOS rats. The supplementation of 0.5 g/kg glutamine could effectively ameliorate the inflammation and oxidative stress conditions of PCOS.

Effect of glutamine supplement on chemo-radiation induced mucositis in head and neck cancer patients: a prospective study

Background: Radiotherapy is one of the primary modalities of cancer treatment but may associated with short and long-term toxicities. Oral mucositis is frequently encountered in head and neck cancer resulting in unplanned treatment breaks. Few studies emphasized that use of oral glutamine may significantly reduce oral mucositis and other acute toxicities. This study aims to assess the effects of glutamine on oral mucositis in head and neck cancer patients receiving chemo-radiation.Methods: It is a prospective study carried out in sixty-four head and neck cancer patients attending radiotherapy department for chemo-radiation from January 2018 to May 2019. Patients were randomly assigned into two arms containing 32 subjects in each. All the patients in arm-A were taking oral glutamine supplement of 15 mg once daily, two hours prior to radiation and arm-B serve as the control group. Dose of radiation fixed at 66 Gy in 33 fractions over a period of 7 weeks along with an infusion of weekly cisplatin (40 mg/m2). Patients were evaluated regarding onset, severity and the recovery period of mucositis.Results: Oral mucositis appeared at around 5th week in arm-A and 3rd week in arm-B (p&lt;0.0001). Number of patients with mucositis is significantly less in arm-A (75%, 24 out of 32) as compared to arm-B (96.8%) (p=0.0310). The time required for healing of mucositis is significantly less than 1 week in arm-A compared to ~2 weeks in the arm-B (p&lt;0.0001).Conclusions: Oral glutamine when given prior to radiation results in delayed onset of oral mucositis with decreased severity and an early healing period.

Effects of glutamine supplementation on performance, mucosal enzymes and intestinal characteristics in broilers

Effects of glutamine supplementation on performance, mucosal enzymes and intestinal characteristics in broilers

Effect Of Glutamine Supplementation On The Cryopreserved Sperm Of South American Catfish

Effect Of Glutamine Supplementation On The Cryopreserved Sperm Of South American Catfish

The Role of Glutamine in the Complex Interaction between Gut Microbiota and Health: A Narrative Review.

The scientific literature has demonstrated that glutamine is one of the main beneficial amino acids. It plays an important role in gut microbiota and immunity. This paper provides a critical overview of experimental studies (in vitro, in vivo, and clinical) investigating the efficacy of glutamine and its effect on gut microbiota. As a result of this review, we have summarized that glutamine could affect gut microbiota via different mechanisms including the reduction in the ratio of Firmicutes to Bacteroidetes, with the activation of NF-κB and PI3K-Akt pathways, reducing the intestinal colonization (Eimeria lesions) and bacterial overgrowth or bacterial translocation, increasing the production of secretory immunoglobulin A (SIgA) and immunoglobulin A+ (IgA+) cells in the intestinal lumen, and decreasing asparagine levels. The potential applications of glutamine on gut microbiota include, but are not limited to, the management of obesity, bacterial translocation and community, cytokines profiles, and the management of side effects during post-chemotherapy and constipation periods. Further studies and reviews are needed regarding the effects of glutamine supplementation on other conditions in humans.

The Effect of Glutamine Supplementation on Microbial Invasion in Surgical Infants Requiring Parenteral Nutrition: Results of a Randomized Controlled Trial.

To determine whether parenteral plus enteral glutamine supplementation influences microbial invasion in surgical infants who require parenteral nutrition (PN). An prospective double-blind randomized controlled trial studying surgical infants receiving PN for at least 5days for congenital or acquired intestinal anomalies (2009-2012) was used. Infants were randomized to receive either glutamine supplementation (parenteral plus enteral; total 400mg/kg/d) or isonitrogenous control. The primary end point was microbial invasion evaluated after 5days of supplementation and defined as: (i) positive conventional blood culture, (ii) evidence of microbial DNA in blood (polymerase chain reaction), (iii) plasma endotoxin level ≥50 pg/mL, or (iv) plasma level of lipopolysaccharide binding protein ≥50 ng/mL. Data are given as median (range) and compared by logistic regression. Sixty infants were randomized and reached the primary end point. Twenty-five patients had intestinal obstruction, 19 had abdominal wall defects, and 13 had necrotizing enterocolitis. Thirty-six infants showed evidence of microbial invasion during the study, and 17 of these were not detected by conventional blood culture. There was no significant difference between the 2 groups in the primary outcome; evidence of microbial invasion after 5days was found in 9/31 (control group) and 8/29 (glutamine group) (odds ratio 0.83 [0.24-2.86; P=0.77]). More than half of surgical infants requiring PN showed evidence of microbial invasion. Approximately half of this was not detectable by conventional blood cultures. Parenteral plus enteral glutamine supplementation had no effect on incidence of microbial invasion.

Effect of Glutamine Supplementation and Leech Therapy on Blood Lactate Level and Pain Index in a Single Bout Exhaustive Exercise in Young Athletes

Background: Glutamine supplementation for recovery is common in sports. Leech therapy has also been used as complementary medicine in traditional Iranian medicine. Objectives: The purpose of this study was to investigate the effect of glutamine intake and leech therapy on blood lactate level and pain index in a single bout exhaustive exercise in athletes. Methods: Thirty-two male athletes (22.2 ± 2.06 years) were selected and randomly divided into four groups (n = 8) of control, glutamine (0.6 g/kg body weight), leech therapy (2 leeches), and combined leech therapy + glutamine. The subjects participated in an exhaustive test. The levels of lactate and muscle pain perception were measured before, immediately after, and a half and an hour after the test. The significance level was considered P ≤ 0.05. Results: In all groups, lactate increased immediately after the activity, the highest increase was observed in the control, leech therapy, glutamine, and glutamine + leech therapy groups, respectively. Also, the most reduction in lactate level was observed in 1 hour and a half hour after the activity, which was related to the glutamine + leech therapy group. The highest reduction in the pain was observed at 1 hour and a half hour after the activity, which was related to the glutamine + leech group. Conclusions: The results showed that glutamine supplementation prior to a single bout exhaustive exercise followed by leech therapy led to a decrease in the lactate level and pain index during the recovery period compared to the other three groups, suggesting that this method may be effective. However, more research is needed to prove the benefits of this method to reduce the lactate and pain subsequent exhaustive exercise.

Neuroprotective effect of glutamine supplementation by inhibiting oxidative stress and promoting autophagy responses after traumatic brain injury in rats

Objective To investigate the effects and mechanisms of glutamine(Gln) supplementation on oxidative stress, autophagy response and neurobehavioral outcome after traumatic brain injury (TBI) in rats. Methods TBI animal models were established using Feeney's method. Eighty SD rats were randomly divided into 4 groups: sham operation group (group Sham), Sham + glutamine supplementation group (group Sham+ GLN), traumatic brain injury group (group TBI), and TBI + glutamine supplementation group (group TBI+ GLN). We measured rat behavioral outcomes by modified neurologic severity score (mNSS) tests at day 1, 3, 7 and 14 after TBI. The apoptosis neurons in TBI cerebral cortex were determined by TUNEL staining. The expression of reactive oxygen species (ROS) was tested by ROS kits. Oxidative stress and autophagy related cytokines (HO-1, NQO1, Nrf2, LC3-Ⅱ and Beclin-1) were tested with Western blotting. Results Compared with the TBI group, the neurological function was improved[(9.79±0.43)vs.(8.43±0.30), F=6.775, P=0.010] and the apoptosis rate decreased(19.88% ±1.60% vs. 15.35% ±1.28%, P=0.013) in the TBI+ GLN group after 7-day treatment. Compared with the Sham group, the protein expression of ROS increased(P=0.000), and the expression of anti-oxidative stress factors (HO-1, NQO1) and Nrf2 pathway significantly decreased in the TBI group. After glutamine supplementation was given, the expression of ROS decreased and the expressions of HO-1 and NQO1 increased. The Nrf2 pathway and autophagy response also were activated with the expressions of Nrf2, LC3-Ⅱ and Beclin-1 increasing. Conclusion Glutamine supplementation can markedly reduce neuron apoptosis and improve neurological outcomes after TBI, thus has the protective effect on nerves by inhibiting TBI-induced oxidative stress response, activating Nrf2 pathway and autophagy response. Key words: Traumatic brain injury; Glutamine; Oxidative stress; Nrf2 pathway; Autophagy

Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition.

Glutamine is a conditionally essential amino acid widely used in sports nutrition, especially because of its immunomodulatory role. Notwithstanding, glutamine plays several other biological functions, such as cell proliferation, energy production, glycogenesis, ammonia buffering, maintenance of the acid-base balance, among others. Thus, this amino acid began to be investigated in sports nutrition beyond its effect on the immune system, attributing to glutamine various properties, such as an anti-fatigue role. Considering that the ergogenic potential of this amino acid is still not completely known, this review aimed to address the main properties by which glutamine could delay fatigue, as well as the effects of glutamine supplementation, alone or associated with other nutrients, on fatigue markers and performance in the context of physical exercise. PubMed database was selected to examine the literature, using the keywords combination “glutamine” and “fatigue”. Fifty-five studies met the inclusion criteria and were evaluated in this integrative literature review. Most of the studies evaluated observed that glutamine supplementation improved some fatigue markers, such as increased glycogen synthesis and reduced ammonia accumulation, but this intervention did not increase physical performance. Thus, despite improving some fatigue parameters, glutamine supplementation seems to have limited effects on performance.

The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials

This systematic review and meta-analysis of available evidence was conducted to obtain a conclusive result on the effects of glutamine supplementation on athletes. Systematic review and meta-analysis. Data related to body mass, lean body mass, body fat percentage, Vo2 max, lymphocytes, leukocytes and neutrophil counts were extracted to determine the effects of GLN on performance outcomes. The literature search was conducted across the databases Pubmed, Scopus, ISI Web of Science, SID (Scientific Information Database) and Cochrane Central Register of Controlled Trials, covering a period up to January 2017. Clinical trials evaluating glutamine supplementation outcomes on athletes aged over 18 were included. A total of 47 studies were included in the systematic review, and 25 trials matched the inclusion criteria for the meta-analysis. According to the meta-analysis, glutamine has a significant effect on weight reduction (WMD=-1.36 [95% CI:-2.55 to-0.16], p=0.02). Moreover, neutrophil numbers were reduced following glutamine intake at doses greater than 200mg/kg body weight (WMD=-605.77 [95% CI:-1200.0 to 52.1]; P=0.03). Also, supplementation by glutamine dipeptide resulted in higher blood glucose after exercise (WMD=0.51 [95% CI: 0.18, 0.83] mmol/l; P=0.002). There was no association between glutamine ingestion and other outcomes investigated. According to this meta-analysis, generally, glutamine supplementation has no effect on athletics immune system, aerobic performance, and body composition. However, the current study showed that glutamine resulted in greater weight reduction. In addition, the present study suggests that the efficacy of glutamine supplementation on neutrophil numbers could be affected by supplement type and dose.