Glutamine is one of the most important amino acids present in the human body.

Glutamine is an abundant substance in the body and is one of the 20 amino acids that make up proteins in the human body.

Glutamine is industrially produced as a white crystalline powder by fermentation of carbohydrate sources and is odorless but has a bitter taste.
It is readily water soluble but hardly soluble in alcohol.

In the pharmaceutical field, glutamine is given orally to patients with gastric and duodenal ulcers.

Glutamine has a variety of benefits.
It is classified as a non-essential amino acid in humans and is said to be a “conditional essential amino acid” because it is easily consumed under stress.
Glutamine is an amino acid that needs to be taken by the body under stress.

Glutamine is known to stimulate the secretion of growth hormone1).
It also stimulates muscle protein synthesis and inhibits muscle protein degradation2).
Glutamine is transported to immune cells and used as a nitrogen source for nucleic acid synthesis and as a substrate for protein synthesis. Furthermore, it is necessary for the division of lymphocyte cells 3) and is said to have an important role in the immune response.
Glutamine is absorbed into the body by ingestion4), and its effects have been demonstrated in animal and human studies1,5,6).
There are few records showing adverse effects on the upper limit of glutamine intake in human food (7th ICAAS Workshop on Assessment of Dietary Amino Acid Amount) 7).

According to clinical trials with adults that test the effects of glutamine on the growth hormone secretion and boost the immune system, the required amount of glutamine is 2-30 g per day1,6,8,9 ).
There is no record of problematic side effects from glutamine intake in this report.
In the recently proposed OSL (Observed Safe level), glutamine has an OSL of 14 g / day10).

In acute oral toxicity studies using rats, glutamine has a lethal dose (LD50 value) of at least 16 g / kg (body weight) 11).

References
1.Welbourne TC.Increased plasma bicarbonate and growth hormone after an oral glutamine load.American Journal of Clinical Nutrition.61(5):1058-61, 1995
2.In-house data at Kyowa Hakko Kogyo Co., Ltd.
3.Newsholme EA.Crabtree B. Ardawi MS.Glutamine metabolism in lymphocytes: its biochemical, physiolog-ical and clinical importance.Quarterly Journal of Experimental Physiology.70(4):473-89, 1985
4.Ziegler TR.Benfell K. Smith RJ.Young LS.Brown E. Ferrari-Baliviera E. Lowe DK.Wilmore DW.Safety and metabolic effects of L-glutamine administration in humans.Jpen:Journal of Parenteral & Enteral Nutrition.14(4 Suppl):137S-46S, 1990
5.Moriguchi S. Miwa H. Kishino Y. Glutamine supplementation prevents the decrease of mitogen response after a treadmill exercise in rats.Journal of Nutritional Science & Vitaminology.41(1):115-25, 1995
6.Castell LM.Poortmans JR.Newsholme EA.Does glutamine have a role in reducing infections in athletes? European Journal of Applied Physiology & Occupational Physiology.73(5):488-90, 1996
7)The 7th Workshop on the Assessment of Adequate Intake of Dietary Amino Acids.The Journal of Nutrition.138, Supplement, 2008.
8.Yoshida S. Matsui M. Shirouzu Y. Fujita H. Yamana H. Shirouzu K. Effects of glutamine supplements and radiochemotherapy on systemic immune and gut barrier function in patients with advanced esophageal cancer.Annals of Surgery.227(4):485-91, 1998
9.Stehle P. Zander J. Mertes N. Albers S. Puchstein C. Lawin P. Furst P. Effect of parenteral glutamine peptide supplements on muscle glutamine loss and nitrogen balance after major surgery.Lancet.1(8632):231-3, 1989
10.Shao A. Hathcock JN.Risk assessment for the amino acids taurine, L-glutamine and L-arginine.Regulatory Toxicollogy & Pharmacology.50(3):376-99, 2008
11.Amino Acid Data Book.Japanese Society for Amino Acid Sciences.2010

・Glutamine and Immune System Support
・Glutamine importance for human health; recent findings and advances