Micronized L-Glutamine 5000 mg Powder [Discontinued] by Natural Factors

EFFECTIVE

• Sickle cell disease. A specific oral glutamine powder (Endari, Emmaus Medical, Inc) is approved by the US Food and Drug Administration (FDA) to reduce acute complications of sickle cell disease. Details: Clinical research in adults and children 5 years of age and older shows that taking glutamine 5-15 grams (0.3 grams/kg body weight) orally twice daily for 48 weeks, either with or without hydroxyurea, delays the median time to first crisis by 30 days, and reduces the incidence of acute chest syndrome by 15%, number of hospitalizations by 33%, and the number of hospitalized days by 40%, when compared with placebo (96519,99414).

POSSIBLY EFFECTIVE

• Burns. Oral glutamine seems to improve healing in patients with severe burns and may also reduce the risk for burn wound infections; however, it is unclear if glutamine improves hospitalization length or mortality. Details: Some clinical research shows that administering enteral nutrition supplemented with glutamine 0.35-0.5 grams/kg daily for 12-14 days, beginning within 24-48 hours of hospitalization for severe burn injury (excluding inhalation injury), decreases the length of hospital stay by 6-9 days and may shorten wound healing when compared to control enteral nutrition (52307,52337). A clinical study in adults with moderate to severe burns (including inhalation injury) shows that administering enteral nutrition supplemented with intravenous alanyl glutamine 0.5 grams/kg daily, beginning within 24 hours of burn injury and continued for 14 days, may improve burn-induced organ damage, particularly intestinal mucosal injury, but does not improve mortality or length of hospitalization, when compared with standard nutritional support (108027). Another study in the same population shows that administering enteral nutrition supplemented with glutamine 4.3 grams every 4 hours, beginning within 24 hours of burn injury, decreases the risk of mortality by 83% and the risk of Pseudomonas wound infections; however, it does not decrease the duration of hospitalization (52311). A meta-analysis of these trials and one additional trial shows that administering glutamine enterally reduces the risk of Gram-negative bacterial wound infections by 73% and reduces the risk of mortality by 87% when compared to a control group. However, there was no difference in length of stay or overall wound infection rate (97363). Results were based on a small number of patients within each outcome evaluation. Intravenous glutamine has also been evaluated. One small clinical study shows that intravenous glutamine 0.57 grams/kg daily decreases the incidence of Gram-negative bacteremia by 35% when compared with control in patients with severe burns. However, it does not appear to decrease the incidence of Gram-positive bacteremia, the need to use antibiotics, or risk of mortality (52272).
• Critical illness (trauma). Oral and intravenous glutamine seem to reduce infectious complications in critically ill adults. However, glutamine does not seem to reduce mortality in this population. Details: Some studies show that glutamine reduces the risk of infectious complications in critically ill, multiple-trauma, or postoperative adult patients (5449,5450,7309,7731,8184,52288,52359). However, other studies show no benefit (52308,52360,97362). Meta-analyses of these and other clinical trials suggest that glutamine supplementation reduces the risk of nosocomial infections in critically ill patients by 15% to 18% and the risk of nosocomial infections in surgical patients by 30% to 41%. This benefit was seen only with parenteral glutamine; enteral glutamine does not appear to reduce the risk for nosocomial infection (91355,91358). The role of glutamine for reducing mortality in critically ill adults is conflicting. Some clinical trials suggest that glutamine-enriched enteral and parenteral nutrition reduces mortality in critically ill patients (52283,52289,52408). However, other studies show no benefit (52288,52308,52354,52359,97362). Meta-analyses of results from these and other clinical trials show that, overall, taking glutamine does not reduce the risk of mortality in critically ill patients (91355,91358). However, the dose and dosage form may affect outcomes. One meta-analysis shows that glutamine does not affect the risk of mortality when administered at doses up to 0.5 grams/kg daily, although doses greater than 0.5 grams/kg daily may INCREASE mortality by 18% (91355). Another meta-analysis shows that glutamine decreases short-term mortality in critically ill patients by 25% when administered parenterally, but not enterally (91358). Neither parenteral nor enteral glutamine appears to decrease the risk of long-term mortality in critically ill patients (91358). Research evaluating glutamine in critically ill children is limited. One clinical study in children ages 1-17 admitted to an intensive care unit (ICU) shows that enteral administration of glutamine along with zinc, selenium, and intravenous metoclopramide does not reduce nosocomial infections when compared with whey supplementation (86095).
• HIV/AIDS-related wasting. Oral glutamine seems to attenuate weight loss related to HIV/AIDS. Details: Very small clinical studies show that taking glutamine orally seems to enhance intestinal absorption of nutrients, decrease intestinal permeability, and increase weight gain in adults with HIV/AIDS when compared with placebo. Doses of 40 grams daily seem to produce the greatest effect (2337,2702). Lower doses of 14 grams daily might also be effective when used in combination with arginine and hydroxymethylbutyrate (a leucine metabolite) (7310).
• Postoperative recovery. Oral or intravenous glutamine seems to reduce the duration of hospitalization and improve postoperative nutritional status in adults. However, it does not seem to reduce postoperative mortality. Details: Although some conflicting evidence exists (52316), most clinical research shows that receiving free glutamine or glutamine-containing dipeptide intravenously decreases the duration of hospitalization after surgery, particularly after major abdominal surgery (2363,5448,7300,7732,52275,52341). A meta-analysis of this research and other studies shows that IV supplementation with glutamine-containing dipeptides reduces the length of hospital stay by 3 days when compared with no supplementation (96507). Other meta-analyses of clinical research also show that glutamine supplementation, as free glutamine or glutamine-containing dipeptides, reduces the risk of hospital-acquired infections by 30% in surgical intensive care unit (ICU) patients and by 41% in elective surgical patients (91355,91358). In cancer patients undergoing abdominal surgery, glutamine-supplemented parenteral nutrition seems to improve nutritional status and gastrointestinal function (100943). Glutamine-containing dipeptides also appear to help to preserve intestinal integrity (7299,7300,7732,52306). One small study has evaluated oral glutamine 10 grams, in combination with arginine 4.5 grams, in patients undergoing surgery for enterocutaneous fistulas. This study shows that taking this combination daily for 7 days prior to surgery reduces recurrence of fistulas by 35%, and also reduces postoperative infections (103837). Although glutamine seems to decrease length of stay and reduce infection rate, it does not appear to reduce the risk of mortality in either surgical ICU or elective surgical patients (91355,91358,96509,103834), including those receiving major abdominal surgery (5448,52316,91355,96507). Additionally, most research shows that glutamine supplementation does not reduce the incidence of infectious complications following abdominal surgery (52306,52316,52341,5448,7300,96507). The effects of glutamine on reducing infection rate might be related to patient population, modes of nutrition, or dose of glutamine. Taking a combination of glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.2 grams (Abound, Abbott) orally daily for 3 days before and 7 days after abdominal surgery does not reduce the incidence of wound infections or other complications (99413). Most of the research evaluating glutamine in surgical patients has been conducted in adults. Information in children is limited. Existing clinical research shows that glutamine-fortified parenteral nutrition does not improve intestinal permeability, nitrogen balance, duration of hospitalization, incidence of infectious complications, or risk of mortality in newborns and infants undergoing digestive-tract surgery (52338,96508).

POSSIBLY INEFFECTIVE

• Athletic performance. Oral glutamine does not seem to improve athletic performance. Details: Small studies in trained athletes or healthy adults show that taking glutamine orally does not seem to enhance performance or immune response during intense acute or prolonged exercise when compared with placebo (2341,2342,5455,5456).
• Crohn disease. Oral glutamine does not seem to improve symptoms of this condition. Details: Small clinical studies in adults and children with Crohn disease show that taking glutamine 7 grams three times daily or following a glutamine-enriched diet for 4 weeks does not seem to improve intestinal permeability or disease activity, and might even worsen disease activity, when compared with placebo or a low-glutamine diet (2338,6256).
• Cystinuria. Oral glutamine does not seem to improve cystinuria. Details: According to case reports, taking glutamine orally does not seem to reduce the excretion of cysteine in the urine in patients with homozygous cystinuria (2339).
• Low birth weight. Oral glutamine does not seem to reduce adverse consequences of low birth weight in infants. Details: Most clinical studies show that glutamine supplementation does not improve the time to full enteral feeding, infant growth rate, or length of hospital stay in low birth weight infants (52305,52312,52325,52342,52362,52410). One follow-up study also shows that neonatal glutamine supplementation is not associated with improvements in cognitive function, motor skills, or behavior outcomes by school age when corrected for neonatal infection rate (52342,97365).
• Muscular dystrophy. Oral glutamine does not seem to improve symptoms of Duchenne muscular dystrophy. Details: Clinical studies show that taking glutamine 0.5-0.6 grams/kg orally does not significantly improve muscle strength or whole body protein degradation in children with Duchenne muscular dystrophy when compared with placebo or a nonspecific amino acid mixture (46657,52363).
• Prematurity. Oral glutamine does not seem to reduce morbidity or mortality associated with prematurity. Details: A meta-analysis of clinical trials in preterm infants, including infants with low to very low birth weight, shows that use of enteral or parenteral glutamine does not reduce the risk of mortality or morbidities, such as necrotizing enterocolitis, when compared with control. However, limited evidence from a sub-group analysis suggests that enteral glutamine might modestly reduce the risk of invasive infection when compared with control (105015). These findings are limited by the selection bias and heterogeneity of the included trials.
• Radiation-induced diarrhea. Oral glutamine does not seem to improve diarrhea due to radiation therapy. Details: One meta-analysis of five randomized, controlled trials shows that taking oral glutamine during radiotherapy for pelvic cancers does not prevent or reduce the severity of diarrhea when compared with placebo (97367).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Antiretroviral-associated diarrhea. It is unclear if oral glutamine improves diarrhea caused by antiretroviral agents. Details: A small crossover clinical study in HIV patients shows that oral glutamine 30 grams daily for 10 days seems to reduce the severity of nelfinavir-associated diarrhea when compared with placebo (52313).
• Alcohol use disorder. Although there is interest in using oral glutamine for alcohol use disorder, there is insufficient reliable information about the clinical effects of glutamine for this condition.
• Attention deficit-hyperactivity disorder (ADHD). Although there is interest in using oral glutamine for ADHD, there is insufficient reliable information about the clinical effects of glutamine for this condition.
• Chemotherapy-induced diarrhea. It is unclear if oral glutamine improves diarrhea caused by chemotherapy. Details: Although preliminary clinical studies show that glutamine might reduce the occurrence of chemotherapy-induced diarrhea (7235,7285), a meta-analysis of this research and others shows no difference in the severity of diarrhea (7233,7295,96516). Despite results showing a significant 1-day reduction in the duration of diarrhea, this might not be considered clinically significant (96516).
• Chemotherapy-induced lymphocytopenia. It is unclear if oral glutamine reduces lymphocytopenia caused by chemotherapy. Details: One small clinical study in patients with esophageal cancer receiving chemo-radiotherapy shows that taking glutamine 30 grams daily for 28 days seems to prevent a reduction in lymphocytes when compared with placebo (2705). However, another small clinical trial in patients with leukemia or lymphoma receiving intensive chemotherapy shows that adding glutamine 26 grams to total parenteral nutrition (TPN), in place of other amino acids, does not affect duration of neutropenia when compared with receiving an isonitrogenous standard TPN (7295).
• Coronavirus disease 2019 (COVID-19). It is unclear if oral glutamine is beneficial in patients hospitalized with COVID-19 pneumonia. Details: A very small, nonblinded, non-randomized evaluation of otherwise healthy patients over 50 years of age who were hospitalized with mild COVID-19 pneumonia shows that taking glutamine 10 grams three times daily orally with meals is associated with a 1-day decrease in hospital stay (from 10 days to 9) when compared with patients not taking glutamine. In the latter group, 4 patients required transfer to the ICU, compared with no patients in the glutamine group (103839). A similar, non-randomized evaluation of adults hospitalized with COVID-19 pneumonia shows that adding the same dose of glutamine to other therapies for 5 days is associated with a 3-day decrease in hospital stay (from 14 days to 11) when compared with patients not taking glutamine. At the end of treatment, 0% of patients in the glutamine group required ICU services, compared with 54% of patients who did not receive glutamine. This study also shows that taking glutamine may increase appetite (108035). The validity of these findings is limited by short duration of treatment and use of non-standardized treatments.
• Cystic fibrosis. It is unclear if oral glutamine improves growth and development in children with cystic fibrosis. Details: A small clinical study in undernourished or stunted children with cystic fibrosis shows that taking glutamine 0.7 grams/kg daily orally for 4 weeks with or without recombinant human growth hormone (rhGH) does not promote protein gain when compared with rhGH alone (52321).
• Diabetic foot ulcers. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a specific nutritional supplement drink containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams (Abound, Abbott) twice daily for 16 weeks does not improve total wound closure or reduce the time to complete healing when compared with a control drink in patients with diabetic foot ulcers (96637). It is unclear if this effect is due to glutamine, other ingredients, or the combination.
• Diarrhea. It is unclear if oral glutamine improves diarrhea in children and infants. Details: One preliminary clinical study in 6-24 month-old otherwise healthy children with acute diarrhea shows that taking capsules prepared with a specific glutamine powder (Power Glutamine, Champion Nutrition) 0.3 grams/kg daily for 7 days reduces the duration of diarrhea by about one day when compared with placebo (52323). However, other clinical research in male infants 1-12 months old with acute diarrhea and dehydration shows that adding glutamine 90 mmol/L along with the standard World Health Organization oral rehydration salts (ORS) does not decrease the duration of diarrhea, stool output, or the volume of oral rehydration solution required to achieve and maintain hydration when compared with standard ORS alone (7298).
• Hematopoietic stem cell transplant (HSCT). It is unclear whether oral glutamine or glutamine added to parenteral nutrition improves morbidity and mortality in patients undergoing HSCT. Some research has suggested that intravenous glutamine may actually worsen outcomes. Details: Some research suggests that patients receiving glutamine-supplemented parenteral nutrition (PN) after HSCT primarily to treat hematologic malignancies have a diminished incidence of clinical infections, lower rates of microbial colonization, and decreased length of hospital stay when compared to control (2366,52381). However, not all patients seem to benefit. Some research shows that oral glutamine or PN with glutamine does not reduce the risk of mortality or infections in patients with hematologic malignancies and/or solid tumors (5451,52385). Also, a small clinical study in patients undergoing HSCT shows that PN with glutamine dipeptide may increase the duration of hospital stay (52292). Furthermore, one small study has found that receiving PN with glutamine was associated with lower disease-free survival and event-free survival over 3 years when compared with standard PN in patients receiving HSCT for hematologic malignancies (52355).
• Irritable bowel syndrome (IBS). There is limited evidence on the oral use of glutamine in patients with IBS. Details: A clinical trial in adults with IBS (diarrhea-predominant, constipation-predominant, mixed, or alternating bowel habits) shows that following a low FODMAP diet supplemented with oral glutamine 15 grams three times daily for 6 weeks improves IBS-Severity Scoring System (IBS-SSS) scores, with 88% of patients in the glutamine group reporting a 45% improvement in severity scores, compared with 60% of patients following the low FODMAP diet alone (108037). The validity of this finding is limited by short duration of treatment and lack of follow-up. Preliminary clinical research in patients with postinfectious, diarrhea-predominant IBS shows that taking glutamine 5 grams three times daily for 8 weeks leads to a nearly 14-fold greater likelihood of symptom improvement, defined as a reduction of 50 points or more on the IBS-SSS, and decreases stool frequency by 2.45 stools daily when compared with placebo. Taking glutamine also seems to reduce abdominal pain ratings by 55% and improve quality of life scores by 53% when compared to baseline in these patients (100944). The validity of these findings is limited by the lack of a comparator group.
• Lung cancer. It is unclear if oral glutamine improves survival in patients with advanced lung cancer. Details: One small clinical study in patients with advanced non-small cell lung cancer shows that taking glutamine 10 grams three times daily for 12 months along with palliative chemoradiotherapy prevents weight loss, which is an important predictor of survival, but does not increase the likelihood of progression-free survival when compared with palliative chemoradiotherapy alone (100942). It is unclear if this study was adequately powered to detect a difference in survival between groups.
• Malnutrition. It is unclear if oral alanyl-glutamine improves height and weight in children at risk for malnutrition. Details: Preliminary clinical research in children aged 2 months to 5 years from a low-income area of Brazil and at risk for malnutrition, shows that taking 3-12 grams of alanyl-glutamine orally daily for 10 days improves gut integrity and is associated with a modest, short-term increase in weight when compared with a glycine placebo (103838).
• Exercise-induced muscle damage. It is unclear if oral glutamine is beneficial for exercise-induced muscle damage. Details: A very small clinical crossover trial in professional athletes undergoing rigorous training shows that taking oral glutamine 6 grams daily for 20 days reduces serum levels of creatine kinase and myoglobin when compared with placebo (108031). The validity of these findings is limited due to the small size and short duration of treatment.
• Obesity. It is unclear if oral glutamine is beneficial for weight loss. Details: A preliminary clinical study in 36 overweight or obese adults shows that taking glutamine 30 grams daily for 2 weeks reduces waist circumference by 1.8 cm, but does not improve body weight, body mass index, or glycemic indices, when compared to baseline. None of these outcomes were improved over baseline in an alanine control group (100941). Given the small study size and short duration of therapy, the long-term effects of glutamine on anthropometric measures is unclear.
• Opioid withdrawal. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in Chinese patients undergoing detoxification from heroin shows that taking a combination of tyrosine, lecithin, 5-HTP, and glutamine 50 mg/kg orally daily for 6 days might reduce mood-related withdrawal symptoms when compared with placebo (88178). It is unclear if this effect is due to glutamine, other ingredients, or the combination.
• Oral mucositis. There is contradictory evidence about the effects of glutamine in patients with, or at risk of developing, oral mucositis from chemotherapy or radiotherapy. Details: Small clinical studies suggest that taking glutamine orally or swishing and swallowing a glutamine solution can decrease the incidence, severity, and duration of oral mucositis in some patients undergoing chemotherapy and/or radiation therapy for cancer or hematopoietic stem cell transplant (HSCT) (2336,2368,2704,5029). Additionally, three meta-analyses of highly heterogeneous clinical trials in patients with cancer receiving chemotherapy and/or radiation therapy suggests that glutamine reduces the incidence of severe (grade ≥3) oral mucositis when compared with control (105014,108028,108036). These analyses are limited for several reasons, including reporting bias, lack of sensitivity analysis, and population heterogeneity. Some small clinical studies included in these meta-analyses suggest that supplementation with glutamine may reduce the need for feeding tubes and opioid analgesics (108028,108036). However, not all research has been positive. Some small clinical studies in patients receiving chemotherapy with 5-fluorouracil for cancer or HSCT suggest that oral or intravenous glutamine does not reduce the incidence of oral mucositis when compared with control (2365,5451,5462,7296,52349,52350). Furthermore, a meta-analysis of 5 clinical trials in patients with head or neck cancers shows that oral glutamine does not reduce the overall incidence or the incidence of moderate to severe radiation-induced oral mucositis when compared with control (103836). The Multinational Association of Supportive Care in Cancer and the International Society for Oral Oncology (MASCC/ISOO) cautiously recommends the use of oral glutamine to prevent oral mucositis in patients with head and neck cancer receiving chemoradiotherapy. However, due to some evidence suggesting that intravenous glutamine may actually worsen outcomes in HSCT patients, the MASCC/ISOO recommends against its use for the prevention of oral mucositis in patients receiving high-dose chemotherapy, with or without total body irradiation, for HSCT (105004).
• Paclitaxel-induced myalgia and arthralgia. It is unclear if oral glutamine reduces the risk for myalgias and arthralgias due to paclitaxel. Details: One small clinical study shows that taking glutamine 10 grams three times daily for 5 days, starting on the day of chemotherapy and repeated over 2 cycles of chemotherapy, does not reduce the rate or severity of paclitaxel-induced myalgias or arthralgias when compared with placebo (52331).
• Pancreatitis. It is unclear if oral glutamine improves outcomes in patients with acute pancreatitis. Details: Two meta-analyses of the available clinical research in patients with pancreatitis show that enteral or parenteral supplementation with glutamine increases albumin, decreases C-reactive protein, and might reduce mortality, multiple organ dysfunction syndrome, hospital length of stay, and infections. Results are difficult to interpret due to the significant heterogeneity of the included trials and limited generalizability of the results (96513,103835).
• Peptic ulcers. Although there is interest in using oral glutamine for peptic ulcers, there is insufficient reliable information about the clinical effects of glutamine for this condition.
• Postoperative infection. It is unclear if oral or intravenous glutamine is beneficial for the prevention of postoperative infection in patients with colorectal cancer who are recovering from surgery. Details: A meta-analysis of nonblinded clinical research in adults with colorectal or colon cancer who recently underwent radical surgery shows that daily supplementation with glutamine 0.3-1 grams/kg, administered either orally or parenterally, improves the rate of surgical site infections and anastomotic leakage when compared with control (108033). These findings are limited by the high heterogeneity of the included studies and unclear reporting.
• Postoperative recovery. It is unclear if oral or intravenous glutamine is beneficial in patients with colorectal cancer who are recovering from surgery. Details: A meta-analysis of nonblinded clinical research in adults with colorectal or colon cancer who recently underwent radical surgery shows that taking either oral or parenteral glutamine 0.3-1 grams/kg daily may reduce the length of hospital stay when compared with control (108033). These findings are limited by the high heterogeneity of the included studies and unclear reporting.
• Pressure ulcers. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in patients with stages II-IV pressure ulcers shows that taking a specific nutritional supplement drink containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams per packet (Abound, Abbott Nutrition) as two packets twice daily by mouth for 2 weeks has no effect on wound area or healing scores by the Pressure Ulcer Scale for Healing (PUSH) measurement when compared with standard nutritional care (96506).
• Radiation dermatitis. It is unclear if oral glutamine reduces the risk of developing dermatitis from radiation therapy. Details: One small clinical study in patients with head and neck cancers receiving cisplatin shows that taking a specific supplement containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams (Abound, Abbott) orally twice daily, starting on day 1 of radiation and continuing until 1 week after radiation therapy, does not reduce the incidence of severe radiation-induced dermatitis when compared with no supplementation (96639). However, another small clinical study in patients with breast cancer who have had both chemotherapy and surgery shows that taking oral glutamine 5 grams three times daily, starting 1 week before radiation and continuing until 1 week after radiation, is associated with a reduction in grade 1 and grade 2 radiation dermatitis when compared with placebo (97366).
• Radiation-induced esophagitis. It is unclear if oral glutamine reduces the risk of developing esophagitis from radiation therapy. Details: A small clinical study in patients with advanced non-small cell lung cancer shows that taking glutamine 10 grams three times daily for 12 months along with a palliative dose of chemoradiotherapy (total 30 Gy) results in a 7% incidence of symptomatic (grade 2 or higher) radiation-induced esophagitis, compared with a 53% incidence with palliative chemoradiotherapy alone. The glutamine group also had a 5.8-day delay in the onset of esophagitis (100942). However, a lower dose of glutamine in patients receiving higher doses of radiotherapy might not be beneficial. A small clinical study in patients with advanced thoracic malignancies shows that taking glutamine 4 grams mixed in water twice daily for 4 weeks along with radiotherapy (total dose of at least 45 Gy) to the esophagus, with or without chemotherapy, does not slow the onset of radiation-induced esophagitis or reduce its severity when compared with a glycine placebo (105011).
• Short bowel syndrome. It is unclear if oral glutamine improves symptoms of short bowel syndrome. Details: Although small clinical studies suggest that glutamine plus growth hormone can decrease dependence on parenteral nutrition in some patients (2334,2361,2362,2703), it has not shown benefit for improving intestinal absorption of energy in all studies (8185). Additionally, glutamine alone doesn't appear to be beneficial (7730).
• Traumatic Brain injury (TBI). It is unclear if intravenous glutamine is beneficial in patients hospitalized with severe TBI. Details: A clinical trial in patients hospitalized for a severe TBI shows that adherence to a hypocaloric, low-protein diet supplemented with daily intravenous glutamine 0.3 g/kg for 7 days does not improve 28-day mortality when compared with standard nutritional support alone. However, it may reduce the length of ventilator use, hospitalization, and duration of intensive care unit stay (108034).
• Vincristine-induced neuropathy. It is unclear if oral glutamine reduces the risk of developing neuropathy from treatment with vincristine in children. Details: Preliminary clinical research in children ages 1-21 years receiving vincristine for various cancer types shows that taking glutamine 6 grams/m2 twice daily orally for 21 days reduces sensory neuropathy when compared with placebo. There was a significant improvement in self-reported, but not parent-reported, quality of life scores as measured by the PedsQL scale. However, there was no effect on motor neuropathy with the use of glutamine (96517).
• Wound healing. It is unclear if oral glutamine improves wound healing. Details: Preliminary clinical research in trauma patients with wound healing disorders shows that taking glutamine 20 grams orally daily in combination with ascorbic acid 500 mg, vitamin E 166 mg, beta-carotene 3.2 mg, selenium 100 mcg, and zinc 6.6 mg (Glutamine Plus, Fresenius Kabi) for 14 days reduces the time to wound closure by 29 days when compared with placebo. However, there is no difference in length of stay (97364). More evidence is needed to rate glutamine for these uses.

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LIKELY SAFE ...when used orally and appropriately. Glutamine has been safely used in clinical research in doses up to 40 grams per day or 1 gram/kg daily (2334,2337,2338,2365,5029,5462,7233,7288,7293), (52288,52307,52308,52311,52313,52337,52349,52350,96516,97366). A specific glutamine product (Endari) is approved by the US Food and Drug Administration (FDA) (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 600 mg/kg daily in clinical trials (2363,2366,5448,5452,5453,5454,5458,7293,52272,52275), (52283,52289,52304,52306,52316,52341), (52359,52360,52371,52377,52381,52284,52385,52408,96637,96507,96516).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Glutamine has been shown to be safe in clinical research when used in amounts that do not exceed 0.7 grams/kg daily in children 1-18 years old (11364,46657,52321,52323,52363,86095,96517). A specific glutamine product (Endari) is approved by the US Food and Drug Administration for certain patients 5 years of age and older (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 0.4 grams/kg daily in clinical research (52338,96508). There is insufficient reliable information available about the safety of glutamine when used in larger amounts in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when consumed in amounts commonly found in foods. There is insufficient reliable information available about the safety of glutamine when used in larger amounts as medicine during pregnancy or lactation.

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ANTICONVULSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, glutamine might antagonize the effects of anticonvulsant medications.  Details Glutamine is metabolized to the excitatory neurotransmitter glutamate. Glutamate might have antagonistic effects with anticonvulsant drugs (7292,7293,7294). However, this interaction has not yet been reported in humans.

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General ...Orally and intravenously, glutamine is generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, bloating, constipation, cough, diarrhea, flatulence, gastrointestinal pain, headache, musculoskeletal pain, nausea, and vomiting.

Endocrine ...One case of hot flashes has been reported in a patient taking glutamine 5-15 grams orally twice daily for up to 1 year (96520).

Gastrointestinal ...Orally, glutamine has been associated with belching, bloating, constipation, flatulence, nausea, vomiting, diarrhea, and gastrointestinal (GI) pain. Nausea, vomiting, constipation, diarrhea, and GI pain have been reported in clinical trials using high-dose glutamine 10-30 grams (0.3 grams/kg) in two divided doses daily to treat sickle cell disease (99414). One case of dyspepsia and one case of abdominal pain have been reported in patients taking glutamine 5-15 grams twice daily orally for up to 1 year (96520). In a small trial of healthy males, taking a single dose of about 60 grams (0.9 grams/kg of fat free body mass [FFM]) was associated with a 50% to 79% incidence of GI discomfort, nausea, and belching, compared with a 7% to 28% incidence with a lower dose of about 20 grams (0.3 gram/kg FFM). Flatulence, bloating, lower GI pain, and urge to regurgitate occurred at similar rates regardless of dose, and there were no cases of heartburn, vomiting, or diarrhea/constipation (105013). It is possible that certain GI side effects occur only after multiple doses of glutamine.

Musculoskeletal ...Orally, glutamine 30 grams daily has been associated with cases of musculoskeletal pain and non-cardiac chest pain in clinical trials for patients with sickle cell disease (99414).

Neurologic/CNS ...Orally, glutamine has been associated with dizziness and headache. A single case of dizziness has been reported in a patient treated with oral glutamine 0.5 grams/kg. However, the symptom resolved after reducing the dose to 0.25 grams/kg (91356). Mania and hypomania have been reported in 2 patients with bipolar disorder taking commercially purchased glutamine up to 4 grams daily (7291). Glutamine is metabolized to glutamate and ammonia, both of which might have neurological effects in people with neurological and psychiatric diseases or in people predisposed to hepatic encephalopathy (7293).

Oncologic ...There is some concern that glutamine might be used by rapidly growing tumors and possibly stimulate tumor growth. Although tumors may utilize glutamine and other amino acids, preliminary research shows that glutamine supplementation does not increase tumor growth (5469,7233,7738). In fact, there is preliminary evidence that glutamine might actually reduce tumor growth (5469).

Other ...Orally, glutamine has been associated with cough when a powdered formulation is used. It is unclear if this was due to accidental inhalation. One case of a burning sensation and one case of hypersplenism has been reported in a patient taking glutamine 5-15 grams twice daily orally for up to 1 year (96520).

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