Glutamine Supplement for Exercise: What You Need to Know

ISSA, International Sports Sciences Association, Certified Personal Trainer, ISSAonline, Glutamine Supplement for Exercise: What You Need to Know

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Supplementation recommendations are generally outside a personal trainer’s scope of practice. Especially if those suggestions are related to supplements used to treat an illness or disease. This sometimes creates a challenge because, as a health professional, clients may expect you to offer some guidance. 

While referring them to a nutritionist or dietitian is often the best response, it is also helpful for you to understand some of the most common supplements within the fitness space.

Creatine is one, with many gym-goers and athletes using this supplement to enhance their body composition. Protein is another. But what do you do when a client comes to you with the desire to begin a glutamine supplementation? 

Creating an effective response begins with understanding what this substance is and why they may want to take it. 

What Is Glutamine?

Glutamine (short for l-glutamine) is the most abundant amino acid in the human body. As an amino acid, it serves as a building block for protein. It stimulates protein synthesis and is essential for cell survival. 

Generally, glutamine is not considered an essential amino acid. Yet, some health experts call it “conditionally essential.” This is because it serves a valuable purpose at certain times. One example of these times is when you’re under a high amount of stress. 

Research reveals that glutamine is the most versatile of the 20 amino acids contained within a person’s genetic code. It assists with the exchange of gases between tissues. It helps stabilize other acids. It also aids in metabolic energy storage and generation. 

Glutamine even serves as a substrate or substance used to create chemical reactions. In this way, it supports cell health and function. In fact, glutamine depletion has been found to lead to cell death.

Amino acids positively impact the immune system. They make it easier to fend off illness and disease. Glutamine specifically offers many advantages in this regard. 

For example, some studies have connected glutamine supplementation with faster wound healing. Another piece of research notes that this amino acid can potentially improve survival rates after a major infection.

While all of this sounds great, you may be wondering why it’s important for you to know all of this. Why do you need to know about glutamine? You’re a personal trainer, after all. Isn’t it more critical that you know how to help clients achieve weight loss and build their muscle? 

Absolutely. You must know how to build muscle mass and increase calorie burn. But you also need to be aware of how supplemental glutamine can affect your clients and their workout. This enables you to provide the proper fitness guidance. It also gives insight into how they may respond.

Benefits of Glutamine Supplement for Exercise

Why would an active individual want to begin glutamine supplementation? As it turns out, there are many reasons that extend beyond protein synthesis.

Enhanced Immune Function

Athletes tend to be hard on their bodies. They push themselves to their physical limits. They’re always striving for more muscle mass or a trimmer figure. This is great for hitting goals and doing well in their sport of choice. It’s not so great for immune function.

Athletes are at a higher risk of upper respiratory infections, especially during periods of heavy training. This is due to their immune system being weakened up to 70 percent post-exertion. Their body becomes more susceptible to infection setting in.

Glutamine supplementation can potentially offer a protective effect. It can help bolster immune function. This helps them stave off the latest bug. It also enables clients to stick to their fitness routine versus being sick in bed.

Reduced Fatigue

Other research indicates that glutamine may help with fatigue. So, clients may take a glutamine supplement in the hopes that it will give them more energy. How does it work?

One study found that glutamine increased muscle glycogen by 16 percent. These glycogen levels remained elevated for two hours post-exercise. The body uses glycogen for energy. Give it more glycogen and workouts aren’t as draining.

Faster Muscle Recovery

Glutamine may also enhance exercise recovery. This is especially true if your client engages in eccentric exercise. 

A May 2018 study looked at this very effect. The group taking oral glutamine and leucine recovered faster than the placebo group. This was determined after measuring multiple factors. Delayed-onset muscle soreness and creatine kinase were two.

If you work out hard, you create muscle damage. Glutamine may help repair muscle tissue damage at a faster rate.

Potential Side Effects

Some people experience side effects with glutamine supplementation. The University of Michigan reports that these effects commonly include:

  • nausea or vomiting
  • gas
  • swelling of the hands or feet
  • muscle pain
  • joint pain 
  • mild rash
  • dry mouth
  • runny nose
  • increased sweating

Taking the glutamine as suggested on the label may help reduce these effects. Taking the supplement at a specific time might help too. 

The University states that the best time to take glutamine varies based on the form of supplementation. Glutamine powder is generally best when taken with food. Yet, an empty stomach may be better with glutamine tablets.

Who Could Benefit from Glutamine Supplementation?

Athletes who want to build up their immune system may find supplementation beneficial. Staying healthy means they’re able to keep up with their workouts. This is even more important during intense training periods. It helps undo some of the stress-related muscle breakdown.

If a client struggles with intestinal issues, they may also find that glutamine provides some relief. For instance, one study found glutamine supplementation helpful in cases of irritable bowel syndrome. The subject’s intestinal permeability normalized after taking the glutamine.

Taking Glutamine Supplements as Part of a Complete Dietary Regimen

Glutamine supplementation is just one piece of the puzzle. It’s not uncommon for clients to take multiple supplements in an effort to improve their health. They may take a branched-chain amino acid (BCAA) to help build muscle mass. Or they might take garcinia cambogia to drop body weight.

When working with clients who use glutamine supplementation, it’s important to consider their entire dietary regimen. Help them understand each supplement they take and how they may interact with each other.

Also work with them so that they realize that many supplements can be found in certain foods. Adding these foods to their diet may make supplementation unnecessary. Foods with a higher glutamine concentration include:

  • protein sources such as chicken and fish
  • vegetables like cabbage, spinach, beets, and peas
  • beans and lentils
  • dairy
  • tofu

Helping Clients Find a Safe Glutamine Dosage 

Providing specific dosage instructions is likely outside your scope of practice. The only exception would be if you also have training as a nutritionist or dietitian.

That said, you can help educate your clients about safe glutamine levels. Point them to the research and let them make their own decisions. For instance, one health researcher reported that up to 0.65 g/kg of body weight is generally well tolerated by healthy adult athletes. However, conclusive research is lacking in this area.

Want to learn more about how nutritional supplements can impact a client’s training? The ISSA offers Nutrition Coach certification. This course covers the various aspects of nutrition and how it can affect athletic performance.



"Recommendations To Maintain Immune Health In Athletes". Taylor & Francis, 2021,

Cruzat, Vinicius et al. “Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation.” Nutrients vol. 10,11 1564. 23 Oct. 2018, doi:10.3390/nu10111564

Sandra C. Blass, et al. “Time to wound closure in trauma patients with disorders in wound healing is shortened by supplements containing antioxidant micronutrients and glutamine: A PRCT.” Clinical Nutrition, Volume 31, Issue 4, 2012, Pages 469-475, ISSN 0261-5614,

Philip Newsholme, Why Is L-Glutamine Metabolism Important to Cells of the Immune System in Health, Postinjury, Surgery or Infection?, The Journal of Nutrition, Volume 131, Issue 9, September 2001, Pages 2515S–2522S,

Neil P. Walsh (2018) Recommendations to maintain immune health in athletes, European Journal of Sport Science, 18:6, 820-831, DOI: 10.1080/17461391.2018.1449895

Coqueiro, Audrey Yule, Marcelo Macedo Rogero, and Julio Tirapegui. “Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition.” Nutrients 11.4 (2019): 863. Available:

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