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Glutamine Benefits
There are many claims surrounding glutamine benefits. Is glutamine good for your gut? Do bodybuilders use it to build muscle? Does glutamine give you energy? Can glutamine boost your immune system?
This article outlines the main benefits of glutamine and the bottom line of whether or not you should be taking it.
What is Glutamine?
Glutamine is an amino acid. Amino acids build new proteins, act as messengers, help our immune system, and support and perform many other functions. Glutamine is a conditionally essential amino acid, meaning our body can make glutamine from other amino acids, but we also get it from our diet. Glutamine is found in meat, eggs, tofu, corn, beans, and other protein foods.
Glutamine is the most abundant amino acid in humans. It is found mostly in our muscles and the liver.
L-Glutamine: What’s the Difference?
You may have seen “L-glutamine” used interchangeably with glutamine, but there is also D-glutamine. The letter in front refers to the molecule’s shape which changes based on the environment. L-glutamine is the form that we find in our food and supplements and is used to make proteins in our bodies, which is why we don’t usually talk about D-glutamine and just use the term glutamine.
The Health Benefits of Glutamine
Because of the variety of roles glutamine plays, its concentration in the body is critical for a multitude of functions, processes, and systems. Here we’ll highlight the major functions of glutamine and the benefits that it has on our health.
Gut Health
Most cells in the body use glucose (sugar) as their primary fuel, but the cells that line our intestines use glutamine more than they use glucose. Enterocytes are the cells in our gut that absorb nutrients from our food into our blood so that they can be used by the body for energy, growth, and repair.
Glutamine is an energy source for enterocytes, which impacts synthesis, maintains integrity, and plays a role in preventing the transmission of bacteria through the gut wall.
IBS Symptoms and Diarrhea
Irritable Bowel Syndrome (IBS) is a common condition resulting in uncomfortable gut-related symptoms such as bloating, pain, and loose stool. Many of these symptoms vary based on the individual, and there aren’t many reliable treatment options available. Glutamine supplementation has been investigated as a molecule that helps repair cells in the gut and improve some of these negative symptoms.
A recent randomized control trial demonstrated that glutamine supplementation in adults with IBS-related diarrhea improved their symptoms and the integrity of the gut. However, greater research is still needed in this area.
Immune Health
Glutamine has two main roles in immunity:
- Precursor for glutathione
- Fuel for immune cells
Glutathione is a small protein and a very important antioxidant. It is important for detoxifying reactive oxygen species, which cause inflammation and lead to diseases such as cardiovascular disease. Glutathione is made from glutamate, and glutamate is made from glutamine.
Similar to the cells in the gut, immune cells use glutamine for fuel. Some of these cells include macrophages, lymphocytes, and neutrophils. When they are working to eliminate intruders in the body or repair damage from trauma or surgery, they require a lot of fuel and they use glutamine.
Muscle Growth and Decrease in Muscle Wasting
Since glutamine is an amino acid, it is directly related to muscle protein synthesis and maintenance because amino acids are the building blocks of proteins. About 80% of all of the glutamine in our body is found in our muscles. After eating amino acid-containing foods, glutamine is transported into the muscles faster than other amino acids.
A recent meta-analysis which reviewed the results of glutamine supplementation on body composition in athletes found that, after glutamine supplementation, they did experience weight loss, but there were no significant relationships between glutamine and lean body mass or fat mass.
Athletic Performance and Recovery
We know that athletic performance is greatly impacted by muscle mass and strength. Amino acids like glutamine are used by the body to build new muscles and repair damaged tissues. While other non-essential amino acids don’t appear to play a large role in turning on protein synthesis, glutamine is different, and studies are looking at the associations between glutamine levels and the rate of protein synthesis.
However, a meta-analysis that examined the relationship between glutamine supplementation and athletic performance found no association between glutamine and aerobic performance. Another review found that while glutamine did decrease certain fatigue markers, this didn’t improve overall performance.
As we mentioned above, glutamine is an important step in the synthesis of glutathione, which we need for inflammation protection and healing after muscle injury. When exercise is extended, more damage occurs to the body, recruiting more glutamine to these tissues and making less available in the plasma. It has been suggested that low glutamine levels after exercise may be related to decreased immunity in athletes, but results are still conflicting.
Glutamine Supplementation: Why Take Glutamine?
Glutamine is given to critically ill patients to support their immune system. The results of L-glutamine supplementation for athletes are controversial and are not as well-researched compared to other supplements like essential amino acids or branched-chain amino acids.
People ingest glutamine in a variety of different forms—protein foods, protein supplements, or isolated amino acid supplements. Additional supplementation from isolated L-glutamine is not necessary since it is not an essential amino acid; however, some people choose to because of its potential benefits.
Types of L-Glutamine Amino Acid Supplements
L-glutamine is the form of glutamine found in supplements. You can purchase it as:
- Pure L-glutamine powder
- L-glutamine capsules
- In complex with other amino acids such as glycine or arginine
Dosing Glutamine Supplements
A recommended glutamine daily dose has not been established given there is insufficient evidence to make recommendations related to the effects on athletic performance and the safety of long-term glutamine supplementation.
Always consult a healthcare professional before starting any new supplements to ensure that you are being safe. Recent studies have used low doses of 3-5 grams/day over the short term.
Risks and Side Effects
Since glutamine is found in our food and naturally in our body, you may be thinking—what are the risks of taking glutamine? Since there is not a large body of research surrounding the long-term effects of glutamine supplementation, especially as it relates to athletic performance, you should exercise caution as there can be risks associated with amino acid supplements.
There have been negative side effects reported from chronic consumption of glutamine at high doses (~40 grams/day). These side effects include:
- Changes to metabolism
- Impaired distribution of amino acids
- Diminished ability to detoxify ammonia
- Impact on the immune system
Consider these side effects and your other sources of glutamine and talk to your healthcare provider before starting an isolated amino acid supplement.
Glutamine Deficiency
Glutamine is a conditionally essential amino acid. This means that under normal conditions, we do not necessarily need to consume it from food to meet our needs and likely won’t experience a deficiency.
The body may use more glutamine than usual under the following circumstances:
- Cancer
- After major surgery
- Sepsis/infection
- Trauma
- Prolonged exercise
If glutamine isn’t supplemented during these times, it could lead to deficiencies.
Glutamine Deficiency Symptoms
After a major surgery or infection, the immune system is working on overdrive, and the immune cells are consuming a lot of glutamine. If it isn’t supplemented, it can result in:
- Diminished action of immune cells
- Worse clinical outcomes
- Greater risk of mortality
- Low levels in the liver and muscles
Bottom Line: Does Glutamine Work?
Glutamine has been well-established as an important amino acid in immune health during times of major trauma and is supplemented to critically ill patients regularly.
In terms of supplementation for other reasons, the research is still conflicting. For individuals who are generally healthy, glutamine supplementation is most likely unnecessary. However, if you are working closely with a health professional and looking to maximize your immunity during your training regimen, then a glutamine supplement may be recommended to you.
Frequently Asked Questions
Is L-glutamine good for you?
Glutamine is an important molecule throughout the body. Foods that contain glutamine include meat, eggs, and beans, which are foods that fit into a healthy and balanced diet and contain a variety of different nutrients. L-glutamine supplements are available for consumption, but their long-term effects are not well understood. Supplementation is not necessary for good health under normal circumstances.
What happens if you take glutamine every day?
Side effects from chronic amino acid supplementation are not well established; however, there have been reports of negative outcomes at high doses. It is best to review your food intake, supplement regime, and health goals with a health professional to determine whether or not you should be taking glutamine daily and how much is safe.
What are the major functions of glutamine?
Glutamine is the most versatile amino acid, playing a variety of roles all over the body. The main roles include:
Precursor for many other compounds involved in immunity and metabolism
Fuel for immune cells
Incorporated into proteins
Fuel for cells lining the gut
