Glutamine
Glutamine is classified as a conditionally essential amino acid. It is synthesized and stored in skeletal muscles. It also, helps build skeletal muscles (up to 60 percent of the amino acid content in skeletal muscle tissue is glutamine). Glutamine easily crosses the blood-brain barrier, and in the brain it is converted into glutamic acid (an amino acid that helps proper brain function), and gamma-aminobutyric acid (GABA) (an amino acid that helps transmit nerve impulses). It is key to the development of DNA and RNA and the cells that function as part of the immune system. Glutamine also regulates acid-base balance, transports nitrogen, removes toxic ammonia from the liver, and promotes intestinal function. Glutamine is found in many foods, but is easily destroyed by cooking. If eaten raw, spinach and parsley are good sources.
Typical dietary intake of L-glutamine is 5-10 grams/day.(For more detailed information, please visit ISM’s searchable database: Nutraceutical Search.)
· Glutamine deficiency may impact on normal tissue tolerance to antitumor treatment, and may lead to dose reductions and compromised treatment outcome. The available evidence suggests that glutamine supplementation may decrease the incidence and/or severity of chemotherapy-associated mucositis, irinotecan-associated diarrhea, paclitaxel-induced neuropathy, hepatic veno-occlusive disease in the setting of high dose chemotherapy and stem cell transplantation, and the cardiotoxicity that accompanies anthracycline use. Oral glutamine supplementation may enhance the therapeutic index by protecting normal tissues from, and sensitizing tumor cells to chemotherapy and radiation-related injury.
o Cancer Treat Rev. 2003 Dec; 29(6): 501-13.
Additionally, an oral supplement of glutamine can increase the selectivity of antitumor drugs (Cao et al. 1999, Decker-Baumann et al. 1999, Miller 1999) by protecting the patient from oxidative damage through an increase in glutathione contents (Rouse et al. 1995 ). Several groups have shown that glutamine can also protect against oxidative damage induced by radiotherapy (Jensen et al. 1994, Miller 1999, Yoshida et al. 1995).o Miguel Á. Medina, Journal of Nutrition. 2001;131:2539S-2542S.
Studies indicate that adjunctive glutamine treatment may improve nitrogen retention, decrease clinical infection and length of hospital stay and reduce the incidence and severity of mucositis after BMT (Bone Marrow Transplantation) and high dose chemotherapy. Glutamine may become a conditionally essential nutrient during certain catabolic states, including after a BMT.o J Nutr. 2001 Sep; 131(9 Suppl): 2578S-84S; discussion: 2590S.
Hepatic (liver) glutamine transport activity remains augmented after tumor resection longer than any other transporter. This suggests a key role for this amino acid in overall hepatic nitrogen metabolism and may partially explain the persistent glutamine depletion that is characteristic of the tumor-bearing host.o Espat et al, Ann Surg. 1995 January; 221(1): 50–58.
catabolic stress or when tumors are proliferating, peripheral glutamine stores are rapidly diminished and the amino acid is preferentially shunted as a fuel source toward visceral organs or tumor tissue. This creates a glutamine-depleted environment, the consequences of which include enterocyte and immunocyte starvation.o Ann. Surg. 220: 411-424.
Dietary supplementation of glutamine could have the beneficial effect of restoring the levels of glutathione inside natural killer cells. Experimental data seem to indicate that a dietary supplement diminishes tumor growth by restoring the function of natural killer cells and improves protein metabolism of the host or patient.o J Parenter Entral Nutr 1994 Nov-Dec; 18(6): 471-6.
o Ann Surg 1995 Apr; 22(4): 420-6.
An oral supplement of glutamine can increase the selectivity of antitumor drugs by protecting the patient from oxidative damage through an increase in glutathione contents.o J Clin Oncol. 1998; 16(12): 3918-19.
o Am J Surg 1996 nov; 172(5):418-24.
o Altern Med Rev 1999 Aug; 4(4): 239-48.
5-Fluorouracil (FU) in association with folinic acid (FA) is the most frequently used chemotherapeutic agent in colorectal cancer but it often causes diarrhea. Glutamine reduces changes in intestinal absorption and permeability induced by FU and may have a protective effect on FU induced diarrhea.
o Gut. 2001 Jan; 48(1): 28-33.