Glutamine

What is Glutamine

Chemical Name: (S)-2, 5-diamino-5-oxopentaenoic acid

Molecular Weight: 146.15

Structrual Formula:

Nitrogen Content: 19.17%

Glutamine (13, 14)

  • Glutamine is classified as a nonessential amino acid since it can be readily synthesized by various tissues such as the skeletal muscles, liver, and adipose tissue
  • Research indicates that glutamine is conditionally essential when the metabolic demand for glutamine exceeds the amount available in the free glutamine pool and that which can be provided by de novo synthesis
  • Glutamine may be metabolized to form glucose in the liver. Under certain conditions (e.g. acidosis), glutamine may also be utilized by the kidneys where it is converted into glutamate and then into alpha-keto-glutarate which enters the renal gluconeogenic pathway
  • Within the small intestines, glutamine is also metabolized into alanine which is further metabolized by the liver as a gluconeogenic precursor

Glutamine and metabolic stress (14, 165, 166)

  • During exercise or other times of metabolic stress (e.g. fasting, severe injury, illness, etc.), the demand for plasma glutamine markedly increases
  • For instance, various cells of the immune system such as the lymphocytes and macrophages depend on glutamine as a primary fuel source, and thus the demand for glutamine increases when an immunological response is mounted
  • The enterocytes of the small intestines are the largest consumers of glutamine accounting for about 40-50% of glutamine consumption
  • Glutamine is required for the synthesis of nucleotides. Thus, a sufficient supply of glutamine is particularly important for rapidly dividing cells such as the enterocytes and the immune cells
  • de novo synthesis of glutamine may be insufficient to meet the physiological demand during times of severe, metabolic stress when the amount of free glutamine is rapidly depleted
  • Glucocorticoid hormones such as cortisol are released during such times of stress and promote the proteolysis of muscle proteins and the release of glutamine into the plasma to attenuate the increased demand for free glutamine
  • During hypoglycemic conditions such as the fasting state (after approximately 12 hours of fasting), the branched-chain amino acids within the muscle undergo the transamination process (under the influence of the glucocorticoid hormones) to yield keto-acids which are available as precursors for gluconeogenesis or ketogenesis.

Glutamine and skeletal muscles (170)

  • The skeletal muscles are the primary sites for glutamine synthesis and storage as glutamine contributes to approximately 60% of the free amino acids within the skeletal muscles. Glutamine is also the most abundant amino acid within the plasma
  • Glutamine is the most abundant amino acid generated in the muscle tissue during this time since glutamine formation is independent of glycolysis whereas alanine is formed directly from pyruvate, the end product of glycolysis
  • The majority of nitrogen loss from muscle tissue occurs during the fasting state through glutamine

Glutamine and Alcohol addition (171, 172)

  • Glutamine passes freely across the blood-brain barrier. Once in the brain, it’s converted to glutamic acid and increases the concentration of GABA (gamma-aminobutyric acid)
  • Both glutamic acid and GABA are essential for proper mental function
  • Because of its action in the brain, glutamine supplements have been recommended for preventing the deleterious effects of alcohol on the brain and for reducing alcohol
    cravings. Finding that has support in clinical trials
  • Some sources describe glutamine as a “brain fuel” capable of stimulaing mental alertness and clear thinking. This use is still unproven
  • As Glutamine helps increase the levels of GABA in the brain, which has a calming effect

Glutamine and Peptic Ulcers (6, 173, 174)

  • One of glutamine’s most important tasks in the body is to nourish cells that line the intestine and stomach
  • Preliminary studies have shown that supplements of glutamine may protect against aspirin-induced gastric lesions and enhance healing of painful peptic ulcer
  • It has also been examined for preventing stress ulcers in individuals treated for severe burns
  • Those with stomach problems associated with Crohn’s disease and ulcerative colitis may theoretically benefit from glutamine

Glutamine and FoodGlutamine and Overweight Problems

  • Glutamine can be found in poultry, fish, legumes and dairy products

Glutamine and Overweight Problems (175,176,177)

Side effect of Glutamine (61)

  • The consumption of large doses of free amino acids may result in intestinal discomfort .E.g. abdominal pains and diarrhea
  • Due to the electrolyte-like properties of the amino-acids

Reference

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  • 171) Simpson CW, Resch GE, Millington WR, Myers RD. Glycyl-L-glutamine injected centrally suppresses alcohol drinking in P rats. Alcohol. 1998 Aug;16(2):101-7.
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  • 174) Shive, W. et al Glutamine in treatment of Peptic Ulcer, Texas State Journal of Medicine, pp 840-3
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  • 176) Goodwin, F. National Institute for Mental Health, Quoted in APA Psychiatric News
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