Glutamine

Glutamine (molecular weight: 146.15 g/mol) is one of the 20 amino acids encoded by the genetic code. Glutamine is a non-essential amino acid, meaning it can be produced by the body and is involved in a variety of metabolic processes. Glutamine has recently been re-classified as a conditionally essential amino acid. This means that while the body can make glutamine, under extreme physical stress the demand for glutamine exceeds the body's ability to synthesize it. During times of stress glutamine reserves are depleted and need to be replenished through supplementation. Glutamine is the most abundant amino acid in the body. Over 61% of skeletal muscle tissue is glutamine. L-glutamine is predominantly synthesized and stored in skeletal muscle. Glutamine is converted into the excitotoxin glutamate within neurons. Glutamine is then transported to the neuron and by the enzyme glutaminase, it is converted to glutamate--the potential excitotoxin. L-glutamine accounts for 30-35 percent of the amino acid nitrogen in the plasma. It contains two ammonia groups, one from its precursor, glutamate, and the other from free ammonia in the bloodstream. Glutamine is one of the three amino acids involved in glutathione synthesis. Glutathione, an important intracellular antioxidant and hepatic detoxifier, is comprised of glutamic acid, cysteine, and glycine.

Glutamine functions, uses, and health benefits

The health benefits of glutamine include immune system regulation, nitrogen shuttling, oxidative stress, muscle preservation, intestinal health, injuries, and much more. Supplemental l-glutamine can be helpful in the treatment of arthritis, autoimmune diseases, fibrosis, intestinal disorders such as ulcerative colitis, peptic ulcers, and connective tissue diseases. Glutamine is the primary source of energy for the various cells of the immune system, including T cells and macrophages. Strenuous exercise, viral and bacterial infections, and stress and trauma in general cause glutamine depletion that starves the immune cells. Glutamine helps to protect the lining of the gastrointestinal tract known as the mucosa. Glutamine supplementation maintains the health of the mucosa (inner wall) of the gastrointestinal tract and inhibits muscle wasting in critically ill patients. Glutamine has been shown to enhance the ability of medications to kill cancerous growths. Many people with cancer have abnormally low levels of glutamine. Glutamine protects the liver during toxic chemotherapy, during acetaminophen toxicity, and following a severe inflammatory injury to the liver. Glutamine is used to protect the lining of the small and large intestines from damage caused by chemotherapy or radiation. Glutamine can aid in healing stomach ulcers and prevent inflammation of the stomach that is caused by chronic use of nonsteroidal anti-inflammatory medications. Individuals with advanced stages of human immunodeficiency virus (HIV) often experience severe weight loss (particularly loss of muscle mass). Glutamine combined with antioxidants or other nutrients may help people with HIV to gain weight. Digestion and normal metabolic function of the intestines are dependent upon adequate amounts of glutamine. Glutamine helps to protect the lining of the gastrointestinal tract known as the mucosa. L-glutamine levels have been found to be decreased in endurance athletes who train too often and at high intensity. Athletes with a strenuous training schedule may be able to reduce the risk of infections by supplementing with glutamine.

Dietary sources of glutamine

Glutamine is plentiful in both animal and plant protein. Dietary sources of glutamine include plant and animal proteins such as beef, pork and poultry, milk, yogurt, ricotta cheese, cottage cheese, raw spinach, raw parsley, and cabbage. Glutamine is found in many foods high in protein, such as fish, meat, beans, and dairy products. Small amounts of free L-glutamine are found in vegetable juices and fermented foods, such as miso and yogurt.

Glutamine dosage, intake

Healthy people do not need to supplement with glutamine. The dose of glutamine will be different for different patients. Follow your doctor’s advice on the supplemental use of glutamine for the support of serious health conditions. The typical dietary intake of L-glutamine is 5 to 10 grams daily. Therapeutic dosages of glutamine range from 1.5 to 6 grams daily, divided into several separate doses.

Glutamine deficiency

Glutamine deficiency develops during periods of fasting, starvation, strict dieting, cirrhosis, and weight loss associated with AIDS and cancer. Deficiencies cause increased permeability of the intestines to allergens and toxins inflammation of the intestines, food allergies, inflammatory arthritis (joint inflammation), fatigue, skin rashes, impaired immune function, poor wound healing and slow recovery from illness. HIV infection appears to induce glutamine deficiency, possibly secondary to the rapid turnover of immune cells that occurs in most stages of the infection. Glutamine deficiency may result in diarrhea, villous atrophy, mucosal ulceration, increased intestinal permeability, and intestinal necrosis.

Toxicity, side effects, interactions, and contraindications

Glutamine supplement is considered safe when used in accordance with proper dosing guidelines. However, a small number of people may experience headaches and other side effects with glutamine. People with kidney disease, liver disease, or Reye's syndrome should not take glutamine. Persons sensitive to monosodium glutamate (MSG) may also want to avoid glutamine supplements, since the body can convert glutamine into glutamate. Methotrexate, a drug used to treat certain kinds of cancer, psoriasis, and rheumatoid arthritis, may interefere with glutamine's effectiveness in treating mouth ulcers resulting from cancer chemotherapy. Supplemental l-glutamine is contraindicated in those hypersensitive to any component of a glutamine-containing product.