L-glutamine, also known as glutamine, is an amino acid. Amino acids are organic compounds often referred to as the building blocks of proteins. They play critical roles in health, such as building new proteins and creating hormones and neurotransmitters (messengers between nerve cells).

Amino acids are considered essential or nonessential. Unlike nonessential amino acids, your body can’t make the nine essential amino acids and you must obtain them through your diet.

L-glutamine is a special type of amino acid categorized as “conditionally essential.” Conditionally essential amino acids only become essential under specific circumstances, such as severe burns, prolonged exercise, pregnancy, trauma, or illness.

As the most abundant amino acid in your body, L-glutamine is an important fuel source for your immune cells. It also fights inflammation, protects cells from damage, and plays many other essential roles in health.

In addition to building proteins, L-glutamine supports health in several ways. It regulates the body’s acid-base balance, supports muscle growth and repair, regulates protein production and use, helps produce certain antioxidants, and removes waste products, like ammonia, from your body.

Below are a few more ways L-glutamine may benefit your health. 

Supports Gut Health

L-glutamine is an important fuel source for intestinal cells and enhances their function and growth.

This amino acid supports gut health by helping maintain a balanced microbiome (the diverse environment of bacteria in your gastrointestinal tract), reducing inflammation in the gut, and protecting intestinal cells from damage.

L-glutamine also regulates tight junctions, protein clusters that regulate how water and nutrients enter the intestines. They prevent potentially harmful compounds, like bacteria and toxins, from getting into the gut.

Due to L-glutamine’s protective effects on the gut, studies show that people who have higher blood levels of glutamine may have a lower risk of digestive system diseases, such as colon cancer, colitis, and Crohn’s disease. However, other studies have found glutamine supplementation did not improve symptoms of Crohn’s disease.

Essential for Immune Function

Immune system cells use L-glutamine at a high rate. It’s necessary for the growth of lymphocytes—white blood cells that produce antibodies to protect the body from disease and infection—and neutrophils, which kill disease-causing compounds like bacteria and fungi.

L-glutamine also regulates levels of cytokines, which are small proteins that regulate inflammation. It reduces the production of pro-inflammatory cytokines, limiting inflammation and supporting immune function.

In some cases, people who are very injured or ill experience a significant drop in their glutamine levels. Supplemental glutamine treatment supports recovery by enhancing the immune system and protecting against organ damage. Studies show that glutamine treatment can reduce infection risk and hospital length of stay in critically ill patients.

L-glutamine administration has also been shown to reduce the risk of complications after surgery and promote recovery in surgical patients. However, more research is still needed to confirm the effects of glutamine in critically ill and post-surgical patients.

Important for Heart Health

L-glutamine is critical to cardiovascular function and helps reduce heart disease risk factors. It plays a central role in promoting the function of endothelial cells, which are cells that line the blood vessels. L-glutamine enhances endothelial cell function and protects the cells against oxidative damage.

The body also uses glutamine to create glutathione, a powerful antioxidant that reduces harmful free radicals and limits oxidative damage to cells. 

Low levels of glutathione have been linked to many chronic health conditions, including heart disease. Maintaining healthy levels of L-glutamine may support optimal glutathione levels, which protects the heart from oxidative damage and prevents heart disease.

L-glutamine may also protect against risk factors for heart disease, such as high blood lipid (fat) levels, insulin resistance, high blood pressure, and high blood sugar.

A study that included 15,040 people with diabetes found that people who consumed more L-glutamine through their diets had, on average, a lower risk of heart disease, heart disease-related death, and death from all causes.

L-glutamine is a conditionally essential amino acid, meaning your body usually makes enough to support its needs. 

Studies show the body produces between 40-80 grams of L-glutamine per day. Under normal circumstances, the body can maintain a healthy L-glutamine level by producing the amino acid internally and by ingesting L-glutamine-rich foods.

However, after specific situations—such as trauma, overexertion, and pregnancy—supplemental L-glutamine may be necessary to meet the body’s demands and maintain normal L-glutamine levels.

• Burns: people with burn injuries can have significant losses of amino acids, including L-glutamine. Supplemental treatment with L-glutamine and other amino acids can help wound healing, improve immunity, and reduce mortality risk in people who’ve experienced burns as well as other injuries and traumas.
• Intensive exercise: Overtraining, such as during high-intensity or prolonged exercises like marathon running, can also lead to low L-glutamine levels. This can suppress the immune system and increase infection rates in overtrained athletes. Research findings suggest that blood levels of L-glutamine may decrease by approximately 20% after one hour of marathon running.
• Pregnancy: L-glutamine also becomes conditionally essential during pregnancy. This is because the pregnant person’s typical production rates are unable to support the needs of both the parent and fetus.

In these situations, L-glutamine intake must be increased through supplementation or increased dietary intake. In critical care settings, L-glutamine is sometimes administered through an IV.

Both plant and animal foods contain L-glutamine. These include:

• Beef
• Pork
• Poultry
• Fish
• Beans
• Milk
• Yogurt
• Cheese
• Spinach
• Parsley

Since L-glutamine is found in many foods and the body naturally produces it, most people can maintain optimal glutamine levels by following a balanced, nutritious diet. 

L-glutamine is available in supplement form, including as a standalone supplement.

It can also be found in products that contain multiple amino acids. These products are available in several forms, such as capsules and powders.

L-glutamine supplements have been linked to several health benefits, such as improving symptoms of sickle cell disease, supporting exercise recovery, improving certain aspects of gut health, and more.

If you’re shopping for an L-glutamine supplement, it’s best to choose products that have undergone independent certification by independent laboratories. This can increase your chances of buying a safe and high-quality supplement.  

There is no determined recommended dose for L-glutamine supplements. Talk to your healthcare provider about dosing and potential medication interactions before starting a supplement.

Your body naturally produces L-glutamine and it’s found in many foods. Taking in normal dietary amounts of L-glutamine isn’t associated with health risks or side effects.

When taken as a dietary supplement, L-glutamine is considered safe for people without health conditions, even when taken in high doses.

However, L-glutamine supplementation may worsen hepatic encephalopathy, a brain disorder that occurs when the liver is unable to remove toxins from the blood, in people with advanced liver cirrhosis.

If you have liver disease or any other health condition, like sickle cell disease, you shouldn’t take L-glutamine supplements without clearing it with your healthcare provider first.

L-glutamine is an amino acid that plays critical roles in health, such as supporting immune and digestive health and protecting against heart disease.

The L-glutamine your body produces and you consume through diet is usually enough to meet your body’s demands. However, some people, such as people who are critically injured, pregnant, or participating in strenuous exercise, may require supplemental L-glutamine to meet their daily needs.