The role of glutamine in maintaining a healthy gut and supporting the metabolic response to injury and infection

Adaptation of protein metabolism in relation to limits to high dietary protein intake

“…Skeletal muscle is thought to be particularly important as a`reserve' of protein that can be drawn upon during critical illness or other stress . Amino acids from the breakdown of muscle protein are used to synthesize glutamine, which is an important substrate for maintaining the function of the gut and the cells of the immune system (Newsholme, 1990;Souba et al, 1990). Measurements of the balance of amino acids across limbs have shown that skeletal muscle takes up amino acids during food absorption and releases amino acids during fasting (Halliday et al, 1988).…”

A double-blind randomized placebo-controlled study of oral glutamine in the prevention of mucositis in children undergoing hematopoietic stem cell transplantation: a pediatric blood and marrow transplant consortium study

“…22 In humans, glutamine plays a role in interorgan nitrogen transport, renal ammoniagenesis and acid-base balance, hepatic glutathione production, preservation of mucosal structure, and function in the intestine; and acts as a required substrate for proliferation of lymphocytes and macrophages. 23,24 During injury or stress, intracellular glutamine concentration falls by 40-50% (approximately 14 g of free glutamine) in uncomplicated cases 25,26 and does not return to normal levels for as long as 30 days after injury. 27,28 The extent of glutamine depletion has been correlated with an increased incidence of mortality.…”

Glutamine on the Luminal Microbial Environment After Massive Small Bowel Resection

“…It acts as a nitrogen transfer vehicle, regulator of protein synthesis, precursor for nucleic acid biosynthesis, and a specific fuel for enterocytes (9) and other rapidly dividing cells such as renal tubular cells, malignant cells, fibroblasts, vascular endothelial cells, and lymphocytes. Therefore, GLN is speculated to affect the activities of gut associated lymphoid tissue (GALT).…”

“…This defense mechanism is composed of mechanical and chemical barriers such as acidity in the stomach, epithelial tight junctions, mucous layer (11), and GALT. GALT contains intraepithelial lymphocytes, Payer's patch, mesenteric lymph nodes, and IgA and secretory components (SC) (9). All of these are dependent on the enterocyte status.…”

“…GLN is also known to maintain the structure and function of the intestine (9), especially the intestinal permeability (10). Considering that IgA and secretory component excreted by the mucosal cells affect bacteria in the intestine, enterocytes may play the initial defense role against luminal microbes and toxins (11).…”