L-Glutamine
What is L-Glutamine?
Supplementing L-Glutamine may be a great option to support the immune system as well as help with leaky gut. However, some hypothesize that it may cause hyperactivity or anxiety in those with autism/ADHD.
L-Glutamine, or just “glutamine”, is one of twenty amino acids that are the building blocks of protein in the human body.
Amino acids are classified as being “essential” or “non-essential”. Essential amino acids can only be acquired through food, while non-essential amino acids are naturally produced by the body. L-glutamine is considered a non-essential amino acid
L-glutamine plays a role in the normal functioning of the immune system and is the preferential fuel for cells of the intestine, which is why many supplement with it to help deal with leaky gut. [2]
Although it hasn’t been studied extensively, some people hypothesize that glutamine supplementation could increase excitability (hyperactivity, anxiety, etc) in those with autism/ADHD due to its conversion to an excitatory neurotransmitter called glutamate that is already seen increased in those with these disorders (see L-Glutamine & Autism in the Research at the bottom for more information).
Sources of L-Glutamine
Is L-Glutamine Beneficial for Autism?
L-Glutamine and Leaky Gut
Leaky gut or intestinal permeability is a condition in which undigested food proteins, bacteria, and toxins “leak” through the intestinal wall causing inflammation and a host of issues. [1]
A normal intestinal wall allows for the controlled trafficking of these things from the gut into systemic circulation, however, with leaky gut these things are able to seep through without control.
L-glutamine is considered one of the most important nutrients for healing leaky gut as it is considered the preferential fuel for enterocytes (cells of the intestinal lining). [2]
Dysbiosis or an imbalance between “good” and “bad” bacteria in the gut microbiome is typically seen in patients with autism. This imbalance can trigger leaky gut which is oftentimes present in those with autism as well. [3]
L-Glutamine and Immune Function
Glucose is considered to be the main fuel source for a majority of cells in our body, but in the 1980s researchers found that glutamine is used just as much if not more than glucose by immune cells. [4]
Specifically, glutamine has been found to be the main fuel for a large number of cells of the immune system including lymphocytes, neutrophils, and macrophages. All of which play an important role in immune and inflammatory responses. [5]
Glutamine has also been found to reduce the rate of infection, inflammation, length of hospital stay, and mortality. [6]
L-Glutamine and Autism/ADHD
Recent concern has been raised around L-glutamine supplementation and Autism/ADHD. This is because glutamine is a precursor to the neurotransmitter glutamate. [7]
Glutamate is the major excitatory neurotransmitter of our nervous system. It plays a role in neuroinflammation in patients with autism and also modulates cognitive functions such as learning and memory. [8]
The levels of glutamate are increased in autism/ADHD while the levels of glutamine are decreased. This could likely be due to genetics common in those with autism which increase the conversion of glutamine to glutamate. [9]
Although there hasn’t been a study specifically looking at L-glutamine supplementation and increased excitability due to conversion to glutamate in those with autism, this is something to be cognizant of if supplementing.
Supplementation
L-glutamine is typically sold in either powder or capsule form. The powder form may be an easier option to sneak into smoothies, oatmeal, etc. as it’s relatively flavorless
Examples of common L-Glutamine supplements include:
Capsule/Softgel
Pure Encapsulated L-glutamine capsules & powder
Jarrow Formulas L-glutamine powder
Klaire Labs L-glutamine powder
DISCLAIMER: Before starting any supplement or medication, always consult with your healthcare provider to ensure it is a good fit for your child. Dosage can vary based on age, weight, gender, and current diet.
Note: All supplements are linked to Amazon for convenience, however, buying supplements on Amazon does not guarantee quality, as there are many “unverified resellers” selling nutrition supplements. To buy supplements that are verified to be sent directly to the consumer, you can create an account on the Autism Dietitian FullScript and search for the respective supplement under “Catalog”.
Authors
Brittyn Coleman, MS, RDN/LD, CLT
Blayne Andrews, Dietetic Intern
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[1] Camilleri M. (2019). Leaky gut: mechanisms, measurement and clinical implications in humans. Gut, 68(8), 1516–1526. https://doi.org/10.1136/gutjnl-2019-318427
[2] Rao, R., & Samak, G. (2012). Role of Glutamine in Protection of Intestinal Epithelial Tight Junctions. Journal of epithelial biology & pharmacology, 5(Suppl 1-M7), 47–54. https://doi.org/10.2174/1875044301205010047
[3] Al-Ayadhi, L., Zayed, N., Bhat, R. S., Moubayed, N., Al-Muammar, M. N., & El-Ansary, A. (2021). The use of biomarkers associated with leaky gut as a diagnostic tool for early intervention in autism spectrum disorder: a systematic review. Gut pathogens, 13(1), 54. https://doi.org/10.1186/s13099-021-00448-y
[4] Shah, A. M., Wang, Z., & Ma, J. (2020). Glutamine Metabolism and Its Role in Immunity, a Comprehensive Review. Animals : an open access journal from MDPI, 10(2), 326. https://doi.org/10.3390/ani10020326 (Retraction published Animals (Basel). 2021 Mar 22;11(3):)
[5] Newsholme, P., Curi, R., Pithon Curi, T. C., Murphy, C. J., Garcia, C., & Pires de Melo, M. (1999). Glutamine metabolism by lymphocytes, macrophages, and neutrophils: its importance in health and disease. The Journal of nutritional biochemistry, 10(6), 316–324. https://doi.org/10.1016/s0955-2863(99)00022-4
[6] Kim H. (2011). Glutamine as an immunonutrient. Yonsei medical journal, 52(6), 892–897. https://doi.org/10.3349/ymj.2011.52.6.892
[7] Holten, A. T., & Gundersen, V. (2008). Glutamine as a precursor for transmitter glutamate, aspartate and GABA in the cerebellum: a role for phosphate-activated glutaminase. Journal of neurochemistry, 104(4), 1032–1042. https://doi.org/10.1111/j.1471-4159.2007.05065.x
[8] Ghanizadeh A. (2013). Increased glutamate and homocysteine and decreased glutamine levels in autism: a review and strategies for future studies of amino acids in autism. Disease markers, 35(5), 281–286. https://doi.org/10.1155/2013/536521
[9] Maltezos, S., Horder, J., Coghlan, S., Skirrow, C., O'Gorman, R., Lavender, T. J., Mendez, M. A., Mehta, M., Daly, E., Xenitidis, K., Paliokosta, E., Spain, D., Pitts, M., Asherson, P., Lythgoe, D. J., Barker, G. J., & Murphy, D. G. (2014). Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study. Translational psychiatry, 4(3), e373. https://doi.org/10.1038/tp.2014.11
