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Use L-glutamine to fuel your body

Amino acids (the basic building blocks of protein) are defined, in part, by the presence of a nitrogen (amine) group and an acidic group attached to a carbon molecule. As an amino acid, L-glutamine is unique in that it contains two nitrogen groups. Circulating glutamine (and its nitrogen) provides metabolic fuel to many of your organs.

An amino acid is considered “essential” if it cannot be manufactured in the body in sufficient quantities to maintain health and must be consumed in food. L-glutamine is critical for human health but is not considered an essential amino acid while a person is healthy. This, however, changes during illness and injury and with excessive stress, when levels are significantly depleted, and it’s then considered “essential”. This is despite the fact that L-glutamine is one of the most abundant amino acids in the body, the serum (blood), the muscles and the cerebrospinal fluid.

The main storage sites of L-glutamine are muscles, so people with greater muscle mass may have a better ability to withstand and recover from stressful events because of the higher levels.


Rapidly dividing cells
L-glutamine is utilised as a source of energy by all rapidly dividing cells, such as the cells of the intestinal lining and various immune cells.


Supporting muscle mass/athletes
L-glutamine is “muscle food”, helping to replenish muscle glycogen after exercise and, by building proteins, to repair injury and rebuild muscle. Part of this action may be due to its ability to induce the release of growth hormone. Without sufficient L-glutamine, muscles begin to atrophy. Taking 2–3g after a workout can be useful for fitness addicts.

Integrity of gut mucosa
L-glutamine is the chief source of energy for the cells of the intestinal lining maintaining its structural integrity. It is critical for the cells lining the gastrointestinal tract and is therefore useful for the prevention and repair of gastric inflammation and gastric ulcers. It’s also useful for inflammatory bowel conditions such as Crohn’s disease, ulcerative colitis, food allergies or any intestinal inflammation. It’s these conditions that lead to leaky gut syndrome. Along the same lines, L-glutamine can undo the damage caused by anti-inflammatory drugs such as aspirin and NSAIDs, maintaining gut wall permeability at a healthy level.

Kidney function
L-glutamine is considered important for the maintenance of the renal tubules, contributing to the healthy function of the kidneys.

Immune system
As a fuel for rapidly dividing cells, L-glutamine is critical to the correct function of the immune system, especially in the rapid production of white blood cells during an infection. Strenuous exercise, viral and bacterial infections, and stress and trauma cause glutamine depletion that starves immune cells. L-glutamine has been used therapeutically to protect against the toxic effects of methotrexate and other chemotherapy drugs, for which it is reported to improve recovery, reduce infections and minimise complications.

Antioxidant & liver protection
Glutathione is a powerful antioxidant compound synthetised in the body that helps protect us from chronic illness and environmental chemical exposure. L-glutamine is a component of this antioxidant as it provides glutamate for its production. Glutathione deficiency tends to equate to lowered L-glutamine.

The critical organ for glutathione synthesis is the liver, although it can be synthetised in all cells. In the liver, L-glutamine assists in the removal of waste products of fat metabolism, preventing fatty build-up. However, in advanced liver disease, it cannot be metabolised correctly and is not as useful.

Central nervous system & brain
The synthesis of glutamine from glutamate is the key pathway for detoxifying ammonia and therefore protects the brain (and the body) from ammonia toxicity. In the brain, L-glutamine is a substrate for the synthesis of both excitatory (glutamate) and inhibitory (gamma-aminobutyric acid or GABA) neurotransmitters. It therefore is intimately involved in multiple critical activities and is an important source of energy for the nervous system. If the brain is not receiving enough glucose, it compensates by increasing glutamine metabolism for energy — hence the popular perception of glutamine as “brain food”. L-glutamine users often report more energy, less fatigue and better mood.

Cardiovascular system
L-glutamine is an important source of fuel for the heart muscle.


Blood sugar control
Glutamine also plays a vital part in the control of blood sugar. It helps prevent hypoglycaemia since it is easily converted to glucose when blood sugar is low, and it is a component of the “glucose tolerance factor” that assists insulin to transport glucose into the cells for energy.


A typical diet provides between 3.5g and 7g of glutamine, but more is synthesised according to need. Despite this, severe stress such as strenuous exercise, infectious disease, surgery, burns, injury or other acute trauma can lead to glutamine depletion.

About 25–30g will be required per day for an adult who has low muscle mass, or 20g/day to restore healthy gut lining. L-glutamine is efficiently absorbed in the small intestine and blood levels reach a peak within an hour after ingestion. 3–10g/day should be enough for a healthy person. This would be easily obtained from reasonable protein levels in the diet. Endurance athletes may need a higher dose after extended exercise.

The main nutrients required to ensure the correct metabolic functioning of L-glutamine are vitamins B6 and folic acid and the minerals zinc, magnesium and manganese.


“Chinese Restaurant Syndrome” — a reaction to MSG — does not happen with L-glutamine but more with glutamate, its sister nutrient. Excessive supplementation of L-glutamine can trigger hypoglycaemia and this can be severe. It can also cause imbalances in other amino acids. If supplementing, take responsibly.

Dr Karen Bridgman

Dr Karen Bridgman

Karen Bridgman is a holistic practitioner at Lotus Health and Lotus Dental in Neutral Bay.

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