Glutamine: the Amino Acid for Gut Health & Muscle Growth

Have you heard about the incredible health benefits of L-glutamine? First used in powder form by people in the fitness industry (including bodybuilders) who were looking to preserve muscle tissue, L-glutamine (also simply called glutamine) is an amino acid that is a building block of protein and needed by your body in large amounts. 

The most common original uses of glutamine powder were to meet the following goals: to lose weight fast, burn fat and help build muscle.

While that remains the case, science now shows that glutamine benefits are abundant. It also promotes digestive and brain health, boosts athletic performance — plus it’s helpful in treating intestinal issues and leaky gut.

In fact, it is one of our top three most recommended supplements overall for treating leaky gut and/or building a lean body. Let’s find out why.

What Is Glutamine?

With the chemical formula C₅H₁₀N₂O₃, glutamine is one of 20 naturally occurring amino acids found in protein foods. It’s also the most abundant amino acid in the bloodstream. It makes up 30 percent to 35 percent of the amino acid nitrogen in your blood.

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It’s known as a conditional essential amino acid. What does “conditional essential amino acid” mean? It means that your body can make some on its own but uses it in large amounts.

It also becomes essential when an individual faces disease or specifically muscle wasting. This can happen in the course of certain diseases or even physical trauma.

Additionally, it’s a conditionally essential nutrient during certain catabolic states, including after bone marrow transplantation.

Amazingly, around 60 percent of your skeletal muscle is made up of glutamine – and supplementing with this amino acid can aid protein synthesis and help naturally balance your pH levels.

Food Sources

Found in both animal and plant proteins (including in high levels in both casein and whey protein), glutamine is also available in supplement form and widely popular in the fitness community and beyond.

Glutamine can be found in animal proteins, such as meats and dairy, along with plant-based protein sources, such as beans, raw spinach, parsley and red cabbage. It’s worth noting, though, that animal proteins tend to provide amino acids that are more digestible than plant proteins.

Studies estimate that most people probably consume between three and six grams of glutamine from their daily diets.

The foods with the most glutamine include:

1. Eggs
2. Tofu
3. Milk
4. Bone broth
5. Grass-fed beef
6. Spirulina
7. Chinese cabbage
8. Cottage cheese
9. Asparagus
10. Broccoli rabe
11. Wild-caught fish (cod and salmon)
12. Venison
13. Turkey
14. Corn
15. Rice

To obtain a healthy amount, a general recommendation is to consume at least three servings of these L-glutamine-rich foods daily.

Benefits

What are the benefits of taking glutamine? New research now shows that L-glutamine benefits the body in the following ways:

1. Improves Gastrointestinal and Immune Health

L-glutamine benefits your overall health by supporting gut function and digestive processes. It can be beneficial if you have a digestive condition, such as:

• irritable bowel syndrome (IBS)
• an inflammatory bowel disease like Crohn’s disease
• ulcerative colitis
• diverticulosis
• diverticulitis
• leaky gut or any of the issues associated with leaky gut (like joint pain, rosacea or any type of autoimmune response)

It’s worth noting that the man famous for discovering the Krebs cycle in the body (also known as the “citric acid cycle“) was the first person to recommend taking L-glutamine for gut-related issues. That’s because Sir Hans Adolf Krebs — a German-born British biochemist who received (with Fritz Lipmann) the 1953 Nobel Prize for Physiology — found that it helped improve a healthy gut-related immune response. Additional research supports this finding.

For example, a study published in the journal of Clinical Immunology found that L-glutamine normalizes the effects of the TH2 immune response that stimulates inflammatory cytokines. The effects of L-glutamine in these studies show that it reduces intestinal inflammation and can help people recover from food sensitivities.

It’s also known to play an important role in maintaining healthy gut microbiota and immunity. It seems helpful for reducing intestinal colonization and bacterial overgrowth of pathogens. This may reduce the risk for widespread issues ranging from constipation to weight gain.

A 2018 article published in Nutrients also states that “in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing.” In fact, glutamine is currently part of clinical nutrition supplementation recommended for immune-suppressed individuals.

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2. Can Help Treat Leaky Gut and Ulcers

There are millions of people struggling with a condition called leaky gut syndrome. It is essentially the main cause of autoimmune disease today.

Leaky gut  can contribute to thyroid issues like Hashimoto’s disease, along with arthritis, skin issues like psoriasis and other serious health concerns.

Because glutamine is the major fuel source for cells of the small intestine, it has been shown to support intestinal health and help treat leaky gut in clinical studies.

A study published in the medical journal Lancet referenced above examined 20 hospital patients and found that supplementing with L-glutamine decreased intestinal permeability. An animal study published in the British Journal of Surgery found that L-glutamine benefits ulcerative colitis and inflammatory bowel disease.

It also shows promise for treating ulcers by providing protection from further damage. Plus, it offers a healthier, natural alternative to antibiotics for the treatment of stomach ulcers.

If you’re unsure if you suffer from leaky gut, this leaky gut test can help. If, indeed, you appear to have leaky gut, L-glutamine is the No. 1 amino acid you need to help heal and repair it. 

3. Supports Brain Health

A precursor to the neurotransmitter glutamate in your brain, glutamine is key to boosting your brain health. Why? A disruption of the glutamine-glutamate cycle can result in all kinds of brain problems, including:

• Reye’s syndrome
• epilepsy
• bipolar disorder
• schizophrenia
• anxiety
• depression
• alcohol addiction

Glutamine can also help stall brain aging. Mitochondrial dysfunction causes abnormal increases in the neurotransmitter glutamate and, again, puts the brain at risk for developing the above problems.

A study conducted at the New York University School of Medicine showed that even mild traumatic brain injury caused brain atrophy, and most of this damage was due to the disrupted glutamine-glutamate cycle and an abnormal increase in glutamate levels.

4. May Improve IBS Symptoms and Diarrhea

Glutamine helps improve IBS and diarrhea by balancing mucus production. This results in healthier bowel movements.

If you have Hashimoto’s or an underactive thyroid, consider making it a part of your hypothyroidism diet. The same goes for anyone who suffers from IBS symptoms like constant diarrhea or ulcerations.

5. Promotes Muscle Growth and Decreases Muscle Wasting

Whether your goal is to increase athletic performance, boost metabolism, improve recovery or even build muscle, research shows that L-glutamine can significantly aid your efforts. During an intense workout, your body becomes stressed, and your muscles and tendons require more glutamine than the amount supplied by a normal diet.

After an intense workout, the levels of cellular glutamine can drop by 50 percent and plasma levels by 30 percent. This muscle-wasting state is a gateway for the body to use your muscle for energy rather than carbohydrates, but glutamine can help prevent this from happening.

Supplementing with L-glutamine allows your muscles to fight and push a bit further. This boosts your strength and helps repair your skeletal muscles.

A study found that glutamine supplementation makes it possible to recover quicker from intense weight training sessions because it improves muscle hydration. This aids the muscle recovery process and reduces recovery time for wounds and burns.

It’s why glutamine supplementation is not only common for bodybuilders in the bodybuilding industry, but in nearly every athletic pursuit these days.

6. May Improve Athletic Performance and Recovery from Endurance Exercise

One of L-glutamine’s main roles in the body is to support detoxification by cleansing the body from high levels of ammonia. It acts as a buffer and converts excess ammonia into other amino acids, amino sugars and urea.

Doing approximately one hour of exercise can cause a 40 percent reduction of glutamine in the body. It can also cause suppressed immune function. This has a negative impact on your resistance training and may lead to overtraining syndrome.

L-glutamine benefits long distance athletes as well by boosting the immune system (T-helper cells). Animal studies have indicated that this increase in T-helper cells may reduce the “stresses” associated with overtraining syndrome.

However, not every study has found that it necessarily boosts performance. One 2019 review that included data from 55 studies observed that glutamine improved some fatigue markers, such as increased glycogen synthesis and reduced ammonia accumulation, but this intervention did not always increase physical performance.

7. Supports Metabolic and Heart Health

Research has indicated that human growth hormone (HGH) levels go up nearly 400 percent after glutamine supplementation. This hormonal response leads to an increase in resting metabolic rate and improves the afterburn effect or EPOC post-exercise.

This afterburn effect is essential for burning fat, weight loss and building lean muscle mass.

Is glutamine good for weight loss? There’s evidence suggesting that it helps burn fat and build lean muscle mass by suppressing insulin levels and stabilizing blood glucose. This enables the body to use less muscle mass to maintain blood sugar and insulin sensitivity in the cells.

In fact, six weeks of supplementation with 30 grams per day of glutamine powder “markedly improved some cardiovascular risk factors, as well as body composition, in patients with type 2 diabetes” in one study. For this reason, L-glutamine benefits diabetics and those with sugar and carb cravings as well.

Emerging evidence also indicates that l-glutamine plays a fundamental role in cardiovascular health by serving as a substrate for the synthesis of DNA, ATP, proteins and lipids. Additionally it seems to have potent antioxidant and anti-inflammatory effects that can reduce risk factors for cardiovascular disease, such as:

• hypertension
• hyperlipidemia
• glucose intolerance
• obesity
• diabetes

Deficiency

L-glutamine is synthesized by the body from glutamic acid or glutamate. If the body is unable to produce enough it needs to get it directly from your diet.

It’s estimated that 70 million Americans now suffer from digestive diseases, so it’s apparent that our diets severely lack certain nutrients that support the digestive tract. While L-glutamine is synthesized by the body from glutamic acid or glutamate, sometimes the body is unable to produce enough — plus the majority of people don’t seem to get enough L-glutamine from their food alone if they eat low-protein diets.

Some reasons that you may run low in glutamine include:

• Eating a low-protein diet
• Undergoing lots of stress
• Exercising intensely
• Battling infections and illnesses
• Undergoing treatments, including radiotherapy and chemotherapy
• Having an immune disorder
• Having a chronic gastrointestinal disorder

This is why supplementing your diet with it is an excellent way to boost your immune system and improve your ability to fight infection and diseases.

Glutamine has even become a common supplement for critically ill patients. According to a study published in the medical journal Critical Care, glutamine dipeptide-supplemented parenteral nutrition “continues to be associated with a significant reduction in hospital mortality and hospital length of stay.”

Supplements and Dosage

Types of L-Glutamine

There are two forms of L-glutamine. You can get regular L-glutamine in what’s called its free form, and it should be taken with food ideally for proper absorption by the body. 

The other type is called trans-alanyl-glutamine or alanyl-L-glutamine. It’s an amino acid attached to another amino acid. That basically means you can digest it much better.

Unlike free-form glutamine powder, you can take it on an empty stomach.

Both forms are best taken right after or right before workouts — with your small meals right before or after workouts for it to support your metabolism and weight loss as well as for muscle building, recovery and preservation.

Dosage Recommendations

Typically, the best dosage is an ingestion between two to five grams taken twice daily and in one study up to 10 grams twice daily for serious power athletes. 

When should you take glutamine? Replenishing glutamine levels after an intense session could take up to five days, so it is important to take it on a regular basis if you do intense exercise.

Some bodybuilders say that glutamine works best when combined with certain brained chain amino acids (BCAAs), especially leucine. Others consume it post-workout with creatine in order to try to improve muscle recovery and restore the body’s energy stores.

Risks and Side Effects

Overall, glutamine seems safe to consume in moderate amounts, especially if taken short term. There seems to be low risk for side effects when taken in doses up to 20 to 30 grams per day, which are considered higher doses but have been used safely in some studies short term.

Although the effects of excess glutamine rarely cause problems, if you take oral glutamine long term, it’s a good idea to also supplement with B vitamins. This especially applies to vitamin B12, which controls glutamine buildup in the body.

Who should not take glutamine? Anyone with a history of kidney disease, liver disease, Reye’s syndrome or cancer should not take this supplement unless working with a doctor, since these conditions can affect how amino acids are absorbed.

If you’re battling cancer and/or undergoing cancer treatments, always speak with your doctor about which supplements may or may not be helpful.

In rare cases, allergic reactions to this supplement have been reported. Stop taking it right away if you experience symptoms like nausea, vomiting, hives, dizziness or pain.

Conclusion

• Glutamine is one of 20 naturally occurring amino acids found in protein foods. It’s the most abundant amino acid in the bloodstream.
• It’s known as a conditional essential amino acid because your body uses it in large amounts. This means you need to keep replenishing your supply. 
• Research suggests that are several important l-glutamine benefits for muscle mass, digestion and brain health. Whether you’re looking to increase your athletic performance, build muscle or improve a health condition such as leaky gut or diabetes, L-glutamine should be a part of your daily diet.
• The top food sources include meat, fish, bone broth, spirulina, cottage cheese, and veggies like cabbage and asparagus.
• You can also take it in supplement form, typically in doses between two to five grams, taken twice daily.