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

Glutamine is a substance that exists abundantly in the body and one of the twenty amino acids that make up the protein in the human body.
Industrially glutamine is produced by fermentation from carbohydrate sources as a white crystalline powder, odorless but with bitter and salty taste. Glutamine is readily soluble in water and practically insoluble in alcohol.
In the pharmaceutical field, glutamine has been administered orally patients with gastric ulcer and duodenal ulcer.
Glutamine has various health benefits. Although glutamine is classified as a nonessential amino acid in humans, it is said to be a "conditional essential amino acid", as it is easily exhausted under conditions of stress. It is an amino acid that the body needs to take under stressful conditions.
It is known that glutamine stimulates the secretion of growth hormone1)And so glutamine stimulates the synthesis of muscle protein and inhibits the degradation of muscle protein2).  Glutamine is carried to the immune cells for use as a nitrogen source for nucleic acid synthesis and as a substrate for protein synthesis. In addition, glutamine is required for lymphocyte division3) and is believed to play an important role in the immune response. Glutamine is known to be absorbed into the body by oral ingestion4), and its effectiveness has been demonstrated in animal and human studies1,5,6).
In respect to upper levels in human diet, few data indicate adverse effects caused by glutamine ingestion (the 7th ICAAS Workshop on the Assessment of Adequate Intake of Dietary Amino Acids)7).
In clinical studies to evaluate the effect of glutamine on stimulating the secretion of growth hormone and enhancing the immune system in adults, the quantity of glutamine needed to be effective has been reported to be 2 to 30 g per day1,6,8,9). No problematic side effects of the intake of glutamine are described in these reports. In OSLObserved Safe levelthat is the idea proposed recently, OSL of glutamine is set as 14g per day10).
The acute toxicity (LD50) values in rats after oral administration of glutamine were found to be 16 g/kg (B.W.) or more11).


1) Welbourne TC. Increased plasma bicarbonate and growth hormone after an oral glutamine load. AmericanJournal 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 peptidesupplements 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