What is L-glutamine and how is it used in the body?

L-glutamine is an amino acid that supports immune function and muscle repair.* It is the most prevalent amino acid in the bloodstream, with the highest concentrations being found in the skeletal muscles and gastrointestinal tract. As a free-form amino acid, glutamine is not connected to other amino acids in a chain – referred to as peptides; rather, it’s in an already broken-down form that is ready to be used by the body. Glutamine is important for cell repair and replication, and the body’s rapidly dividing cells need high amounts of it, particularly in the intestinal tract and lymphatic system.*

Stress factors from injury, poor nutrition, or intensive athletic training can adversely affect the body’s ability to absorb glutamine, which can lead to a less robust immune response. In addition, because glutamine is the primary fuel for the cells of the small intestine, low glutamine stores can lead to leaky gut. Increasing glutamine consumption has been shown to reverse and repair the effects of such stressors.*1

Here are three key benefits that glutamine provides for the body:

1: Fuel for cells*

The body’s cells are in a constant state of change, replicating and replacing about 330 billion cells each day.2 Replication requires a lot of energy, especially when healing after an injury. In response to such stresses, glutamine stores are pulled from the bloodstream into the liver where they are converted to glucose for use as cellular energy.* This can lead to a deficiency in the body’s glutamine stores.3

Beyond abnormal traumatic stressors, the body uses glutamine for regulating the epithelium – the tissue that forms the lining of internal organs and skin.* In fact, glutamine is the most important fuel for the cells of the small intestine.*

2: Support for injury recovery*

The amino acids stored in skeletal muscle, including glutamine, are depleted when a person is injured. That is because an injury increases the body’s metabolic rate, which causes an increased need for certain nutrients. When a person suffers from a deficiency or an increased need for glutamine, the body struggles to synthesize glutamine for the needed recovery. Proper nutrition and supplementation are key factors in repairing the body after strenuous activity or traumatic injury, helping it to replenish stores of wound-healing compounds.*

Studies show that patients recovering from traumatic injury who took a glutamine supplement experienced faster healing times.* Their wounds4,5 and bone fractures6 healed faster than individuals who didn’t take a glutamine supplement.* Because of this, glutamine is routinely included as part of clinical nutrition for patients both before and after surgery.7 For less traumatic injuries, such as muscular strain during intense exercise, glutamine supplementation was found in a double-blind study to ease muscle soreness and stimulate quicker strength recovery in both men and women – with more significant effects in men.*8

3: Immune function maintenance*

Because a large part of the immune system resides in the GI tract, glutamine plays an important role in maintaining intestinal health.* By nourishing the cells that line the GI tract, glutamine fortifies the barriers inside the intestines and the rest of the body, helping control what the body absorbs and what it keeps out.*

A lower level of glutamine in the bloodstream hinders the body’s ability to fight off infections; likewise, increasing the amount of glutamine in the diet offers immune support.*9 Athletes, in particular, should be aware of glutamine’s effect on immune function because heavy physical activity can result in a lower level of glutamine in the bloodstream, especially for individuals who compete in endurance events or overtrain themselves.*10 

How to supplement your diet with glutamine

Glutamine is found naturally in many protein-rich foods, like beef, eggs, milk, and tofu. Grains such as rice and corn, although low in total protein content, also serve as good sources of glutamine.

Looking to ensure an adequate daily intake of glutamine? Thorne offers two forms of L-glutamine: one encapsulated for on-the-go ease and one powdered – NSF Certified for Sport and unflavored – to blend into any beverage of choice.

Check out Thorne’s entire line of wellness solutions featuring L-glutamine support.


  1. Hu K, Feng L, Jiang W, et al. Oxidative damage repair by glutamine in fish enterocytes. Fish Physiol Biochem 2014;40:1437-1445. doi: 10.1007/s10695-014-9938-3
  2. Sender R, Milo R. The distribution of cellular turnover in the human body. Nature Med 2021;27. doi:10.1038/scientificamerican0421-76
  3. Demling RH. Nutrition, anabolism, and the wound healing process: an overview. Eplasty 2009;9 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2642618/ [Accessed 6.15.22]
  4. Blass SC, Goost H, Tolba RH, et al. Time to wound closure in trauma patients with disorders in wound healing is shortened by supplements containing antioxidant micronutrients and glutamine: a PRCT. Clin Nutr 2012;31(4):469-475. doi: 10.1016/j.clnu.2012.01.002. 
  5. Arribas-López E, Zand N, Ojo O, et al. The effect of amino acids on wound healing: a systematic review and meta-analysis on arginine and glutamine. Nutrients. 2021;13(8):2498. doi: 10.3390/nu13082498. 
  6. Polat O, Kilicoglu SS, Erdemli, E. A controlled trial of glutamine effects on bone healing. Adv Therapy 2007;24:154-160. doi: 10.1007/BF02850003
  7. Cruzat V, Macedo Rogero M, Noel Keane K, et al. Glutamine: metabolism and immune function, supplementation and clinical translation. Nutrients 2018;10(11):1564. doi: 10.3390/nu10111564. 
  8. Legault Z, Bagnall N, Kimmerly DS. The influence of oral L-glutamine supplementation on muscle strength recovery and soreness following unilateral knee extension eccentric exercise. Int J Sport Nutr Exerc Metab 2015;25(5):417-426. doi: 10.1123/ijsnem.2014-0209.
  9. Calder PC, Yaqoob P. Glutamine and the immune system. Amino Acids 1999;17:227-241. doi: 10.1007/BF01366922
  10. Walsh NP, Blannin AK, Robson PJ, et al. Glutamine, exercise and immune function. Sports Med 1998;26:177-191. doi: 10.2165/00007256-199826030-00004