#Guttok: Are L-Glutamine Supplements Needed for Gut Health in Healthy Populations?
The topic of gut health is trending on TikTok (1). Social media influencers are sharing their gut health struggles and tips to “hack’ your gut”, using hashtags such as #guttok, #guthealth and #guthealing (1). Recently, this included promoting the use of L-glutamine supplements to heal the gastrointestinal (GI) system. The content targets individuals experiencing various ailments, including diarrhea, constipation, bloating and other symptoms associated with a ‘leaky gut’ (2). Social media viewers are encouraged to take a glutamine supplement to help heal the gut lining by “strengthening the intestinal wall”. According to influencers, L-glutamine supplements can increase the rate of cell regeneration, leading to many health benefits.
An undergraduate nutrition student along with the PEN® Team thought an investigation into the effectiveness of L-glutamine supplements marketed to help heal and improve gut health would be helpful to dietetic practitioners whose clients are asking if they should take these supplements.
What does the evidence say?
The evidence supporting the use of L-glutamine supplements in healthy populations is limited, and there may be considerations related to gastrointestinal discomfort (3-5). Experimental studies (in vitro, and in vivo animal and human clinical studies) looked into the role of L-glutamine supplementation and its impact on the GI tract (3,4). In animals, glutamine supplementation had a potentially positive impact on intestinal microbiota composition, cell development and constipation and these were noted as key areas for future human research (3,4). A 2020 clinical trial in 14 healthy males (aged 20-30 years) looked at GI tolerance of oral L-glutamine supplementation in beverages (0.3 to 0.9 g/kg/fat free mass) and found that GI symptoms were greater on high versus low dose consumption (5). Symptoms were generally mild (discomfort, nausea, belching, upper GI pain) within the first two hours after eating.
Studies examining the effect of glutamine supplements on irritable bowel syndrome (IBS) symptoms are sparse. A small 2021, short-term study from Iran (n=50, six-week trial duration) randomized individuals diagnosed with IBS to a low FODMAP diet with a glutamine supplement (15 g/day) or a low FODMAP diet with a placebo (6). After six weeks, IBS-symptom severity scores improved in both groups, but to a greater extent in those who followed the low FODMAP diet with glutamine compared to the low FODMAP diet with placebo (58% versus 46% reduction, respectively).
Some research has focused on the effects of glutamine supplementation when the body is undergoing stress (3,7-11). Stress such as burns, during trauma, sepsis (7-9) or intestinal diseases, such as Crohn’s disease (10), may cause the body to produce insufficient amounts of glutamine (3). A 2021 systematic review examined the effects of glutamine supplementation on inflammatory bowel diseases, like Crohn’s, by reviewing evidence from randomized controlled trials (n= 7 studies) (11). The study authors report no effect on disease course with glutamine supplementation, including intestinal permeability, oxidative stress and inflammation markers. This included observations on the route of administration (oral, enteral and parenteral) and treatment location (in hospital and outpatient).
With limited evidence, it remains uncertain whether L-glutamine supplementation will have any clinical significance in improving GI health in generally healthy individuals. When glutamine is added to a low FODMAP diet, improvements in symptoms in individuals diagnosed with IBS may occur, but this needs to be confirmed in additional studies and should not be inferred to healthy individuals. In addition, high dose supplementation may result in adverse gastrointestinal side-effects. Future research that better explores glutamine supplementation’s effect in humans improving gut microbiota composition, constipation and overall GI health is needed before nutrition practice recommendations can be made.
Written by Julia Yeh, BSc Candidate in the Food, Nutrition and Health Program, University of British Columbia. Reviewed by the PEN Team.
- Blum D. Why is gut health taking over TikTok? New York Times. 2022 Apr 20. Available from: https://www.nytimes.com/2022/04/20/well/eat/tiktok-gut-health.html
- Cassetty S. Do you need supplements to heal your gut? Experts weigh in. Today, NBC News. 2022 Jul 6. Available from: https://www.today.com/health/diet-fitness/supplements-for-gut-health-expert-opinion-rcna36865
- Kim MH, Kim H. The roles of glutamine in the intestine and its implication in intestinal diseases. Int J Mol Sci. 2017 May 12;18(5):1051. doi: 10.3390/ijms18051051. PMID: 28498331; PMCID: PMC5454963. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454963
- Perna S, Alalwan TA, Alaali Z, Alnashaba T, Gasparri C, Infantino V, et al. The role of glutamine in the complex interaction between gut microbiota and health: A narrative review. Int J Mol Sci. 2019 Oct 22;20(20):5232. doi: 10.3390/ijms20205232. PMID: 31652531; PMCID: PMC6834172. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834172/
- Ogden HB, Child RB, Fallowfield JL, Delves SK, Westwood CS, Millyard A, et al. Gastrointestinal tolerance of low, medium and high dose acute oral L-glutamine supplementation in healthy adults: A pilot study. Nutrients. 2020 Sep 27;12(10):2953. doi: 10.3390/nu12102953. PMID: 32992440; PMCID: PMC7601811. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/32992440/
- Rastgoo S, Ebrahimi-Daryani N, Agah S, Karimi S, Taher M, Rashidkhani B, Hejazi E, Mohseni F, Ahmadzadeh M, Sadeghi A, Hekmatdoost A. Glutamine supplementation enhances the effects of a Low FODMAP Diet in irritable bowel syndrome management. Front Nutr. 2021 Dec 16;8:746703. doi: 10.3389/fnut.2021.746703. PMID: 34977110; PMCID: PMC8716871. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/34977110/
- Heyland DK, Dhaliwal R. Role of glutamine supplementation in critical illness given the results of the REDOXS study. JPEN J Parenter Enteral Nutr. 2013 Jul;37(4):442-3. doi: 10.1177/0148607113488421. Epub 2013 May 2. PMID: 23639898. Citation available from: https://pubmed.ncbi.nlm.nih.gov/23639898/
- Dietitians of Canada. Does immunonutrient supplementation improve patient outcomes in critically ill adults? In PEN: Practice-based Evidence in Nutrition. 2018 Nov 21. Available from: https://www.pennutrition.com/KnowledgePathway.aspx?kpid=21017&pqcatid=146&pqid=27272
- Mundi MS, Shah M, Hurt RT. When is it appropriate to use glutamine in critical illness? Nutr Clin Pract. 2016 Aug;31(4):445-50. doi: 10.1177/0884533616651318. Epub. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/27246308/
- Akobeng AK, Miller V, Stanton J, Elbadri AM, Thomas AG. Double-blind randomized controlled trial of glutamine-enriched polymeric diet in the treatment of active Crohn's disease. J Pediatr Gastroenterol Nutr. 2000 Jan;30(1):78-84. doi: 10.1097/00005176-200001000-00022. PMID: 10630444. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/10630444/
- Severo JS, da Silva Barros VJ, Alves da Silva AC, Luz Parente JM, Lima MM, Moreira Lima AÂ, Dos Santos AA, Matos Neto EM, Tolentino M. Effects of glutamine supplementation on inflammatory bowel disease: A systematic review of clinical trials. Clin Nutr ESPEN. 2021 Apr;42:53-60. doi: 10.1016/j.clnesp.2020.12.023. Epub 2021 Jan 21. PMID: 33745622. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/33745622/