Walk into any supplement shop, and you'll no doubt run across tubs of L-Glutamine.
You’ve likely encountered it before (if not in a supplement store, then certainly in one of the many ads on social media), but you may not be sure what it is, what it does, or if it’s even worth using.
Today, we cover why glutamine is essential, as well as the multitude of benefits of L-Glutamine.
Let’s get started!
What is L-Glutamine?
L-Glutamine is a conditionally essential amino acid found throughout the body, including skeletal muscle tissue.
As you may recall, amino acids are the building blocks the body uses to create proteins, which can then be used for many functions, including muscle repair, hormone synthesis, and countless other biological processes.
As a conditionally essential amino acid, the body typically has great glutamine stores on hand or can synthesize the amount of glutamine needed when called upon. Glutamine is the most abundant amino acid in the body. Some estimates indicate that between 30-35% of all nitrogen derived from the breakdown of proteins is transported in the form of glutamine.
However, in situations of considerable stress (such as trauma, prolonged illness, or exhaustive exercise), glutamine requirements outpace the body's ability to create it, which means the body needs to get it from food or amino acid supplements, such as Steel Fuel®.
What is L-Glutamine Good For?
As the most abundant amino acid in the body, it comes as little surprise that L-Glutamine serves in several important roles, including[1,2,3]:
- Protein synthesis
- Glycogen replenishment
- Ammonia buffering
- Maintenance of the acid-base balance
- A carrier of nitrogen between tissues
- An essential precursor of nucleic acids, nucleotides, amino sugars, and proteins
- As a fuel for rapidly proliferating cells, such as those of the GI system as well as the immune system
Interestingly, research has found that the rate of glutamine consumption by immune cells is similar or more significant than glucose.
Let's now take a closer look at some of the glutamine's specific functions in the body.
Glutamine and GI Health
As mentioned above, glutamine serves as an essential fuel source for cells of the GI system and is essential for the growth and survival of enterocytes.
In case you weren't aware, the cells of the GI tract serve as a barrier to the diffusion of toxins, allergens, and pathogens. In other words, our gut lining helps keep out the microscopic baddies that could otherwise invade, infect and harm us. Keeping it happy and optimally functioning is essential to health.
Disruption of this gut barrier can lead to the diffusion of harmful substances known to induce mucosal inflammation and tissue injury.
Research indicates that glutamine may help reduce pro-inflammatory cytokine production by the human intestinal mucosa and help maintain mucosal integrity and barrier function under physiologic and pathophysiologic conditions.[4,5]
Glutamine and Immune Support
In addition to serving as an essential fuel source for enterocytes, glutamine also serves as a crucial fuel source for immune cells. The rate of glutamine consumption by all immune cells is similar or more significant than glucose during periods of illness or infection.
Glutamine also supports many critical functional activities of immune cells, including:
- T-cell proliferation
- B-cell differentiation
- Cytokine production
- Antigen presentation
- Neutrophil superoxide production
While glutamine is typically readily available in the body, increased demand for glutamine by immune system cells, coupled with the increased use of it by other tissues, such as the liver, may lead to a glutamine deficit. Something else to keep in mind is that while skeletal muscles are one of the primary sites for glutamine production, they reduce their contribution to maintaining plasma glutamine concentration during times of illness, which can increase the importance of glutamine intake either from whole food sources or amino acid supplements.
Moreover, the gut plays a significant role in immunity. The cells of the gut (and the immune system) largely depend on glutamine to survive, proliferate, function properly, and ultimately defend our body against microscopic ne'er-do-wells.
Glutamine and Muscle Recovery/Growth
Glutamine is an amino acid involved in the construction of protein, including those found in muscle tissue. Furthermore, muscle tissue also happens to be one of the main sites for glutamine synthesis in the body. To top it off, glutamine availability and metabolism are directly associated with skeletal muscle tissue.
Approximately 80% of the body glutamine is found in the skeletal muscle.
Regarding performance, glutamine can help offset fatigue (thereby allowing you to train harder and do more work in your training sessions) by serving as a readily available fuel source for muscles, buffering ammonia, and attenuating muscle damage.
It may also support recovery since glutamine directly stimulates glycogen synthesis via activation of glycogen synthase.
Glutamine also serves as an important osmolyte for cell volume control. Osmolytes are organic compounds that regulate fluid volume and help cells absorb and retain more water, promoting better hydration. The better hydrated a cell (or muscle) is, the greater its stamina, fatigue resistance, and thermo-regulation.
Glutamine and Skin Health
In addition to all the benefits mentioned thus far, glutamine also plays a role in the health and quality of your skin and other connective tissues. Glutamine is necessary for the health of fibroblasts -- cells that synthesize the extracellular matrix and collagen.
Where Can I Find Glutamine?
The good thing about glutamine is that your body can produce it in sufficient quantities under normal circumstances (hence its classification as “conditionally” essential), and it’s also easy to acquire from a diet rich in protein.
As such, foods naturally rich in L-Glutamine include:
- Dairy (milk, yogurt, cheese, whey protein, etc.)
- Red Meat
- White Rice
One thing to keep in mind regarding the plant sources of glutamine is that while they may supply a decent amount of L-glutamine, their overall protein content is low (especially compared to red meat, chicken, and other animal-based proteins.
If you are looking for a plant-based option that's high in protein, make sure to check out our top-rated plant protein, Steel Vegan™, which supplies 20 grams of high-quality, plant-derived protein in every scoop.
Glutamine is a conditionally essential amino acid that serves several vital roles in the body. It can be obtained in sufficient amounts from high-protein foods, such as beef, chicken, or eggs. It can also be found in dietary supplements, including amino acid supplements and protein powder.
For the average individual who only trains a couple of times per week, glutamine supplementation likely isn't necessary, but if your someone who pushes themselves to the limit day in and day out, increasing glutamine intake may support recovery and immune function, helping you to train harder more frequently and ultimately get better results, faster!
- Lacey JM, Wilmore DW. Is glutamine a conditionally essential amino acid? Nutr Rev. 1990 Aug;48(8):297-309. doi: 10.1111/j.1753-4887.1990.tb02967.x. PMID: 2080048.
- Bowtell JL, Gelly K, Jackman ML, Patel A, Simeoni M, Rennie MJ. Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. J Appl Physiol (1985). 1999 Jun;86(6):1770-7. DOI: 10.1152/jappl.1918.104.22.1680. PMID: 10368336.
- Coqueiro AY, Rogero MM, Tirapegui J. Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition. Nutrients. 2019;11(4):863. Published 2019 Apr 17. doi:10.3390/nu11040863
- 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
- Rao R, Samak G. Role of Glutamine in Protection of Intestinal Epithelial Tight Junctions. J Epithel Biol Pharmacol. 2012;5(Suppl 1-M7):47-54. doi:10.2174/1875044301205010047