L-Glutamine Benefits for Brain, Medical Use & Side Effects

L-Glutamine Benefits, Medical Use & Side Effects

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L-Glutamine Benefits, Medical Use & Side Effects

L-Glutamine Benefits

What is L-Glutamine?

L-Glutamine is the formal name for the glutamine found in humans and most animals. It has a chemical formula of C5H10N2O3 with the most crucial part of its composition the attached ammonium ion. The formation of L-glutamine in the body allows for neurotransmission and the removal of ammonia from the body.

L-Glutamine is one of several alpha group amino acids, meaning that it has a protonated -NH3 molecule, an alpha-carboxylic acid, and a side chain amide. The L-glutamine refers specifically to a type of glutamine that is easier to manufacture that in the typically small doses used is absorbed as efficiently as regular, or isoglutamine. In normal body functions, L-glutamine is an intermediate product of the breakdown of glutamine.

While the most abundant amino acid in the human blood stream and considered conditionally essential, the body is usually capable of synthesizing enough of this amino acid. But in cases of extreme physical or mental stress, extra L-glutamine may be required from diet or supplements. Most glutamine is stored in the muscles and lungs, and it is believed by many to help immune system function and brain function.

On its own, L-glutamine is a dry powder at room temperature, easily dissolved in water or other liquids. This makes it easily put in capsule form for a stand-alone supplement or added to other amino acids and nutrients as part of a shake mix.

The L in L-glutamine is used to distinguish it from its rare isomer, D-glutamine, which has slightly different properties because of the variance in its structure. D-glutamine is found mostly in the cell walls of some bacterias and has no known use or function in more complex organisms.

History of L-Glutamine

Glutamine was first discovered by Schulze in 1893 when he separated the amino acid from beet juice. It was later found that glutamine was prevalent in wheat and many types of meat and eventually synthesized in a lab from glutamate and ammonia by Krebs in 1935.

Because of its conditionally essential status among amino acids, various treatments involving L-glutamine supplements have been trialed with most showing that the body used metabolic pathways exclusive to L-glutamine. At first, this was in intensive care patients, as it was found that recovery was more successful when extra L-glutamine was given to patients.

After finding these effects in traumatic recovery, the bodybuilding and athletic community picked up on the usage of glutamine. The thinking was that as exercise taxes their bodies similar to that of people in medical trauma; it only made sense that glutamine would aid them similarly. While studies have proven inconclusive as the little difference was found between supplementing and a typically high protein diet used by bodybuilders and athletes, L-glutamine has remained a part of the training table.

Because of its role in the composition of neurotransmitters, many believe that L-glutamine can be used to boost mental performance, especially regarding energy and memory. Also, many who have used L-glutamine have reported being sick less often, leading to potential avenues for using L-glutamine to boost the immune system. (3)

While the benefits of mental acuity and the immune system are just considered anecdotal and in need of further study, many are starting to feel that glutamine and L-glutamine supplements are beneficial in these aspects of personal health.
The potential for L-glutamine has barely been touched at this point as there are many uses that, while needing further study could prove beneficial physically and mentally.

L-Glutamine Medical Uses

Glutamine, as an amino acid, first and foremost is part of the protein and lipid synthesis in the body. On the cellular level, it is also used as a secondary energy source when glucose is unavailable. Because of this, the body uses glutamine to normalize glucose levels in the bloodstream as well as maintain proper pH. Glutamine, because it is non-toxic, can carry ammonia in the blood, aiding in muscle recovery from exertion or other stresses.

Along with this primary function, glutamine regulates acid-base balance in the kidneys. Glutamine then sheds its ammonia once it reaches the kidneys and being broken down to glutamate. The ammonia is turned into urea and passed out of the body. This helps filter impurities out of the blood and maintain general health.

The shedding of an ammonium ion, when broken down also, leads to it having a prominent role in nitrogen donation for the anabolic synthesis of purines, which help build DNA and RNA leading to cell growth. In fact, glutamine is utilized especially in cases of rapid cell growth and light tested levels of glutamine can be a precursor to cancer.

Activated immune cells, especially those in the gut, benefit from glutamine. This is on glutamine’s role in improving the barrier function of the intestinal lining. This only is from oral intake of glutamine as opposed to intravenous dosage, which is why glutamine is added to those who are being fed via tubes as it also protects the intestines from breaking down due to inactivity.

Glutamine is believed to create this improvement by strengthening the cells that line the intestines and give them an extra energy source to produce more mucus. This also is why glutamine is recommended for treatment of the leaky gut syndrome. A thicker mucus lining of the intestines fortifies them, keeping their contents from leaking into the rest of the body while allowing vitamin absorption to continue unencumbered.

It is at this time inconclusive whether glutamine supplementation improves these functions in general use. Regardless, studies have shown that the body’s production of glutamine can decrease in times of stress, leading to a potential benefit to increasing intake of glutamine.

Proven L-Glutamine Benefits

6 Proven Benefits of L-Glutamine

The biggest issue to determining L-glutamine benefits is that there have been few studies completed that investigate its role in many different functions. As well, with its commonality in the body and dietary abundance, it is hard to gauge actual dosage, let alone attribute anything to its increase or decrease in the body.

1. Gastrointestinal Health

Most of the current research involving the benefits of L-glutamine have included gastrointestinal health due to its effects on reducing the permeability of the intestinal lining and balancing mucus production. This leads to healthy bowel movements as well as aiding in the rebuilding and repair of the intestines. As there are theories that immune responses start from the “gut,” L-glutamine’s positive effects on intestinal health are a clear aid to immune health.

2. Countering Stress

Exercise or other stress can lead to an increase in ammonia levels in the body. Ammonia is toxic to the body; meaning that L-glutamine’s role in reducing these levels aid in recovery whether you are performing aerobic or anaerobic exercise or suffering other physical or mental strain. Increased ammonia levels can cause kidney, liver or other damage to the body, as well as lead to growing fatigued faster as the body needs to spend more energy to detoxify itself.

3. Building Muscle

Glutamine, as an amino acid, leads to the building of muscle. Increased levels will allow your body to push further and stave off the body using muscle to replenish its lacking glutamine. This improves energy by preventing power loss to recovering muscle loss during exertion. As there have been studies showing that general daily stress can lead to muscle loss much like exercise, it is likely that glutamine supplementation can aid in preventing said injuries.

4. Improved Memory and Concentration

As glutamine is also a precursor to neurotransmitter amino acids, studies are showing a direct benefit to remembrance, focus, and concentration with an increase in dietary intake of L-glutamine. Reports are that with a deeper store of glutamine and its byproducts in the body, the brain is better able to handle stress. This can lead to not only better mental performance, but avoid feeling run down from long hours of studying or working. Further research is required to form a conclusion, but at this point, there appears to be some benefit to memory function and energy for those taking L-glutamine supplements.

5. Easier Sleep

Glutamine also aids in helping the body fall asleep and sleep more restfully, similar to melatonin. This is believed to be done by reducing the amount of ammonia in the bloodstream and neural pathways. Also, the healing benefits of glutamine to muscles and nerves seem to aid in reducing the energy needed for recovery. Many studies have shown that easier and more restful sleep can help improve memory function, bolster concentration and provide more energy.

6. Lowering Neural Degradation

Other studies have shown that those under stress tend to have lower glutamine levels in their bloodstream. Because of this, studies are being done to further explore the potential benefits and stress reduction abilities of L-glutamine. As well, studies are showing glutamine supplements help minimize the effects of some forms of dementia and other mental issues related to aging.

Nutrition Facts & Calories of L-Glutamine

On its own, a gram of L-glutamine has a total of four calories and one gram of protein. Being a protein, it will lack fat or carbohydrates, as well as any vitamins or minerals. Since it’s hard to take that small of an amount of anything effectively, most L-glutamine comes in a capsule or a powdered supplement. Depending on the fillers used, this will have at least some marked increase in the calories consumed, and potentially will add carbohydrates and fats.

Recommended L-Glutamine Dosage

The typical recommended dose is between 2 and 5 grams twice a day, although athletes are encouraged to take up to 10 grams per dose. As the body tends to be able to produce most of the glutamine needed, there is a diminished benefit and potentially a detrimental effect, which we will get to below, to increased dosage. Regardless of why you are taking L-glutamine, it appears that this dosage produces the desired results, as usual, your body will only be short a few grams at most.

In many cases, with an increase of meat, dairy, wheat, cabbage, beets, beans, spinach or parsley, one can increase the amount of L-glutamine in their system without a supplement. Because of the benefits of having extra L-glutamine in the body, a standalone supplement is recommended in most cases as it gives the body the glutamine it needs directly before it needs to be utilized. Even then, it is often suggested that L-glutamine, when taken in a supplemental form be taken on an empty stomach and with B12 to reduce potential adverse effects to an overaccumulation of glutamine in your body.

Possible L-Glutamine Side Effects

While glutamine is considered possibly safe when taken within recommended dosage, there are avenues of use that have not been sufficiently studied. Along with these unknown areas, several conditions can be made more severe with glutamine. As well, higher doses of L-glutamine can have adverse effects on its own.

Pregnant and breastfeeding women are discouraged from taking L-glutamine supplements as there has been a little study done on the consequences of any level of dosage. As well, it is encouraged to limit dosage in children to no more than .7 grams per kilogram of weight daily as there is a lack of study done on the safety of higher doses on children.

As glutamine has a role in liver function, those with cirrhosis and other severe liver diseases are highly discouraged from taking L-glutamine supplements as it is likely to worsen these conditions. People with a sensitivity to monosodium glutamate (MSG) will likely suffer a similar sensitivity to L-glutamine because the body converts glutamine to glutamate. Those with kidney diseases or on dialysis should also avoid L-glutamine because of its increase in ammonia levels in the body through its processing.Finally, there is concern that glutamine affects those diagnosed with mania or suffering from seizures dramatically, and are also discouraged from increasing their glutamine levels.

Taking a higher than recommended dose of glutamine most commonly can have various effects on the digestive system including nausea, vomiting, flatulence, abdominal pain, constipation, and hemorrhoids. Beyond these side effects, overdosage of L-glutamine can cause mental issues, including depression, insomnia, dizziness in many cases. In some rare instances, it is believed that L-glutamine also lead to joint and muscle pain, although that has been discounted in many cases as general overexertion.


1. Amino Acids Guide, “Glutamine,” http://www.aminoacidsguide.com/Gln.html, 2007-2016.
2. Heffley, Dr. James, Ph. D., “What is the Difference Between l-glutamine and glutamine, and the same for other amino acids?” http://www.austinchronicle.com/columns/2006-06-23/378574/. June 23, 2006.
3. Rudolf, Maximilian, “How l-glutamine Increases Memory and Cognitive Function,” http://ezinearticles.com/?How-L-Glutamine-Increases-Memory-And-Cognitive-Functions!&id=6671925. November 4, 2011.
4. Amino Acid Studies, “Amino acids and their significance for sleep, mood and performance,” http://www.aminoacid-studies.com/areas-of-use/sleep-mood-and-performance.html. 2016.

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