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The Benefits of L-Glutamine

What is L-Glutamine?

L-Glutamine is a conditionally essential amino acid naturally occurring in both whey and casein protein. It is one of the 20 amino acids used for the construction of proteins in the body. As a conditionally essential amino, the body can synthesize enough l-glutamine to meet its requirements under normal circumstances.


However, in times of stress (such as intensive exercise, injury or illness), the body cannot synthesize enough glutamine to meet demand. In these times, supplementation with L-glutamine may be necessary.


What Does L-Glutamine Do?


Glutamine is the most abundant and versatile amino acid in the body, accounting for as much as 60% of the total amino acid pool found in skeletal muscle.[1]


Due to the high muscle content of glutamine, it comes as little surprise that the amino acid is involved in protein synthesis.


But, that’s not all.


Glutamine also plays a key role in both immune function and gut health. Extensive bouts of intense exercise can predispose athletes to heightened risks of illness or GI distress. Glutamine supplementation may help to reduce these risks due to the pivotal role it plays in the function of both the immune and gastrointestinal systems.


Glutamine is synthesized in skeletal muscle tissue and from there is transported into the bloodstream where it is delivered to the various tissues in need of it.


Additionally, L-Glutamine can also serve as a type of “fuel” for various cells in the body (including lymphocytes and macrophages), due to its high carbon and nitrogen content.


Note: this fact becomes particularly important following severe illness, injury, or surgery, as nitrogen is in high demand for wound repair and organ function.


In fact, ~⅓ of all the nitrogen needed for these processes is generated from glutamine. It is situations such as these that the demand for glutamine increases, and the body cannot produce sufficient glutamine, making supplementation with L-glutamine that much more necessary.


Glutamine also serves as an important building block for glutathione -- the body’s primary antioxidant. As such, glutamine plays a supporting role in the body’s defense against reactive oxygen species (ROS), oxidative stress, and inflammation.[2]


Glutamine is even involved in cognitive function!


It serves as the precursor for the excitatory neurotransmitters glutamate and aspartate as well as the inhibitory amino acid, gamma-aminobutyric acid (GABA).[3]


Do I Need to Supplement with L-Glutamine?


The answer to this question ultimately boils down to your current diet and exercise program.


If you are someone who performs a lot of intense training during the week then you may want to strongly consider supplementing with L-Glutamine.


Additionally, if you are someone who is sick and/or under a lot of emotional or psychological stress, then you may want to supplement with L-Glutamine, due to the fact that illness and stress significantly ramp up the body’s need for glutamine to support immune and GI function.


Is L-Glutamine Supplementation Safe?


Generally speaking, yes.


L-Glutamine supplementation appears to be relatively safe as research has found no severe adverse effects from its use.


The Observed Safety Limit (OSL) of L-Glutamine supplementation is 14 grams per day in supplement form (i.e. the amount consumed in addition to what you would get from your daily meals).[4]


FYI, the Observed Safety Limit is the highest amount an individual can ingest and be assured of no side effects.


Anecdotally, consuming excessive amounts of L-Glutamine (10-20g) in a relatively short amount of time has been known to lead to GI distress.


The Bottom Line on L-Glutamine


L-Glutamine is the most abundant amino acid in the body and plays a significant role in protein synthesis, immune function, and gut health.


Glutamine may also help enhance glycogen replenishment and support cognitive function.


During normal circumstances, the body can generate enough glutamine to meet its needs.


However, in times of extreme duress (extensive amounts of intense exercise, injury or illness), the body cannot synthesize enough glutamine, which makes the need to supplement with glutamine more critical to sustain health, wellness, recovery, and performance.


Where to Find L-Glutamine


Due to the importance L-Glutamine plays in the human body, 1UP has included L-Glutamine in a number of its amino acid-based formulas, including:


1UP His BCAA contains 2.5 grams of L-Glutamine per serving alongside 8 grams of essential amino acids (including 6g BCAA) as well as joint support and hydration aids.


1UP Her’s BCAA contains 2 grams of L-Glutamine per serving along with 6 grams of essential amino acids (including 5g BCAA) as well as 2 grams of hydrolyzed collagen.


1UP Natural BCAA contains 2.5 grams of L-Glutamine alongside 5 grams of 2:1:1 BCAAs. Natural BCAA is also vegan friendly and naturally sweetened.


1UP Pure Rebuild contains a sizeable 5 grams of pure L-Glutamine along with quality doses of creatine, essential amino acids, and electrolytes to support muscle recovery and growth following training.



  1. Cruzat V, Macedo Rogero M, Noel Keane K, Curi R, Newsholme P. Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation. Nutrients. 2018;10(11):1564. Published 2018 Oct 23. doi:10.3390/nu10111564
  2. Michael Gleeson, Dosing and Efficacy of Glutamine Supplementation in Human Exercise and Sport Training, The Journal of Nutrition, Volume 138, Issue 10, October 2008, Pages 2045S–2049S, https://doi.org/10.1093/jn/138.10.2045S
  3. Wang, L., Maher, T. J., & Wurtman, R. J. (2007). Oral L-glutamine increases GABA levels in striatal tissue and extracellular fluid. FASEB Journal : Official Publication of the Federation of American Societies for  Experimental Biology, 21(4), 1227–1232. https://doi.org/10.1096/fj.06-7495com
  4. Shao A, Hathcock JN. Risk assessment for the amino acids taurine, L-glutamine and L-arginine.Regul Toxicol Pharmacol. (2008)

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