Benefits of Glutamine in Your Personal Training Nutrition Plan


Including glutamine in your personal training nutrition plan can help supercharge for endurance training and recover adequately.

Benefits of Glutamine in Personal Training Nutrition Plan

There is a continuous discussion among scientists about how to supercharge for endurance training and recover adequately.

Carbohydrates are the main fuel for exercising muscles, but they are just one of the pieces needed to close the circle and bring you one step closer to your peak performance. To optimize your performance, you need to concentrate on many aspects. One aspect many endurance athletes often underestimate is their immune system and intestinal health. We already wrote about the delicate relationship between the immune system and the gut and how our good bacteria positively affect athletic performance. Well, there is a substance that can enhance multiple systems in your body, immune, and digestive included. It is glutamine.

Glutamine is usually associated with muscle building, but that is far from the truth. Glutamine is very important for all athletes, especially those who carry out regular endurance training and engage their muscles for long periods. This article will explain why glutamine is so important for endurance athletes and should be included in your personal training nutrition plan and how it can help you reach your peak performance.

What is Glutamine?

Glutamine is one of the eleven non-essential amino acids that the body can synthesize on its own. The human body uses 20 amino acids for protein synthesis, 9 of which are considered essential because our body uses external sources like food and supplements to synthesize them. Some scientists consider glutamine "conditionally" essential amino acid. That is because the body in certain diseases and conditions does not synthesize sufficient amounts of glutamine. Accounting for about 60% of the skeletal muscle tissue, glutamine is the most abundant amino acid in our body. The highest concentrations are found in tissues where it plays a significant role in physiological functions. Glutamine is crucial for the proper function of the digestive, immune, and muscular systems. It acts as a type of fuel for cells, especially for those that divide rapidly. When needed, the body can convert glutamine into glucose or glycogen to get the energy it needs. Glutamine also participates in the synthesis of other amino acids and glutathione, a potent antioxidant.

Primary functions of glutamine

• Transport of nitrogen - Amino acids consist of oxygen, carbon, hydrogen, and nitrogen atoms. Glutamine, which contains two nitrogen atoms, acts as a carrier of this substance between the blood and cells. Nitrogen is an essential molecule for tissue regeneration and growth.

• Protein synthesis - Glutamine makes up a large part of the muscle and bone tissue, making it essential for the muscle tissue growth process.

• PH regulation - Its ability to release and accept nitrogen molecules gives glutamine a buffering capacity to protect the body from sudden pH changes.

• Energy metabolism - Glutamine is as crucial as glucose for energy production. The cells of the kidney, brain, and immune system choose glutamine as their primary energy source.

• Synthesis of neurotransmitters – glutamine is a precursor of two major brain neurotransmitters: Glutamate and GABA.

Glutamine deficiency

Glutamine deficiency occurs more frequently in people with an active lifestyle. For example, some studies report a significant decrease in blood glutamine levels after an hour of intense exercise. This deficiency will be particularly relevant in case of injuries, allergies, infections, stress, an unbalanced diet, or after endurance training.

Scientists also linked glutamine deficiency with "overtraining syndrome" and the "leaky gut syndrome." Both conditions affect athletic performance and recovery in a significant way. The first one results in fatigue and loss of muscle mass, and the second one makes the athlete vulnerable to chronic inflammation, weight loss, and abdominal discomfort.

Symptoms of glutamine deficiency

Normal blood glutamine levels are around 600 µmol / L.

Check your glutamine levels if you experience two or more of the following symptoms:

• Increased frequency of infections

• Gastrointestinal problems

• Fatigue

• Loss of muscle mass

• Weight loss

• Difficulty in wound healing processes

The health benefits of glutamine

The health benefits of glutamine are numerous, and they play an important role in reaching your peak performance.

All the systems in our body are connected, and the malfunctioning of one system can cause multiple problems to other body systems. Glutamine intake will positively affect several systems in your body and reduce the possibility of future health issues during and after training and competitions.

In the next few paragraphs, we will explain why your diet should be packed with glutamine sources, and when should you consider taking glutamine supplements.

The role of glutamine for intestinal health

Glutamine is an important energy source for cells of the immune system and intestine. In fact, most of the benefits linked to glutamine are related to its ability to promote intestinal and immune system health.

Principal functions of glutamine in the intestine include:

1. Maintaining nucleotide metabolism

2. Maintaining the intestinal barrier function

3. Modulation of inflammation

4. Regulating stress responses and apoptosis (programmed cell death)

Several experimental studies have shown that glutamine is a crucial component for maintaining a healthy mucous membrane. Glutamine is sometimes referred to as the "intestinal permeability factor." Epithelial cells of the small intestine called enterocytes, use glutamine as the primary fuel for metabolic functions (about 30% of all glutamine). Its deficiency is thought to lead to a loss of epithelial cell integrity, leading to "leaky gut" syndrome. Increased intestinal permeability allows pathogens and toxins to pass through the intestinal mucosa and trigger a strong immune reaction. That can lead to abdominal discomfort and other conditions that could stop you from finishing the race or recover as planned. Therefore, glutamine promotes overall immune health and your performance by supporting intestinal cells.

The importance of glutamine for the immune system

Glucose is the primary fuel for most of our body cells; immune system cells included. Many immune system cells, such as lymphocytes and macrophages, use glutamine as a source of energy in the same or greater amount in which they use glucose. The supply of glutamine to the body is crucial for athletes. Optimal glutamine levels protect against possible infections to which the body is exposed due to stress and preserve muscle integrity.

Leukocytes, macrophages, and glutamine

The principal role of white blood cells (leukocytes) is to protect our body against pathogens.

Lymphocytes are a type of leukocytes, and we can distinguish two main types:

1. B cells

2. T cells

B Lymphocytes function is to produce antibodies that fight pathogens like viruses and bacteria. Glutamine acts as an energy substrate for lymphocytes, and it plays a crucial role in their rapid reproduction, supporting a fast immune response. Macrophages are cells of our immune system involved in the detection and destruction of pathogens. They produce pro and anti-inflammatory cytokines - crucial proteins for a proper immune system function. The activation of macrophages, just as the secretion of cytokines, is also regulated by glutamine availability. Inflammatory response on muscle repair after intense training is influenced by cytokines, more precisely, by the balance between pro and anti-inflammatory cytokines production. The balance between these two types of small proteins seems to attenuate an exaggerated inflammatory reaction, promoting faster muscle recovery.

During high-intensity training, immune cells begin to use glutamine at higher rates. At the same time, there is an increased demand for glutamine by other tissues. The skeletal muscles, which are the most important glutamine stock and synthesis site, also consume glutamine during endurance training, lowering its overall availability. This can cause a drastic reduction in glutamine levels. Immune cells begin to have their function impaired because of the lack of glutamine, and your body undergoes a suppression of the immune system. The temporary suppression of the immune system is associated with the increased risk of catching a common cold, flu, and other conditions after intense training or competitions.

Glutamine and its role in tumors

Cancer cells can proliferate rapidly. For this, they need "building material" - molecules necessary to synthesize the components of the new cells. Glutamine is an amino acid and an important nitrogen source, an essential constituent of nucleotides, the "building blocks" of which DNA is made. Therefore, cancer may cause glutamine depletion. Some studies reported that a high-glutamine diet might have a beneficial effect on cancer patients. It can also diminish the side effects of chemotherapy and radiation and support improved survival.

Potential mechanisms of glutamine effects in cancer patients include:

• Maintenance of mucosal integrity

• Improved immune response

• Inhibition of cell proliferation and growth

• Increased apoptosis rate (cancer cell death rate)

• Increased synthesis of glutathione

Glutamine and Oxidative stress

Glutamine is a precursor of glutathione, one of the body's most important antioxidants. Intense training and competitions stimulate the production of reactive oxygen species, associated with cellular damage and apoptosis. Glutathione is the most potent antioxidant that our body can produce. The components of this vital molecule are glutamic acid, cysteine, and glycine. Glutamine, being a precursor of glutamic acid, plays an essential role in the synthesis of glutathione. Therefore, it is an important factor in preventing oxidative damage as glutamine enhances your body's antioxidant defense system. Oxidative stress can deplete glutathione in the upper respiratory tract's epithelium and enhance susceptibility to pathogens like viruses that cause common cold and flu.

Glutamine supplements

Endurance training represents physical stress for the body. After exercise, plasma and muscle glutamine levels decrease, as the muscles use this substrate to produce energy and save glycogen reserves. The supplementation of glutamine acts as an exogenous energy source and allows rapid muscle recovery while maintaining the immune defenses at adequate levels. It is possible to increase glutamine levels with two forms of this amino acid: slow-release glutamine peptide or immediate-release L-glutamine, ideal for quick recovery after physical exertion.

1. L-glutamine – Glutamine performs its first functions immediately in the intestine, which causes a reduction of absorption in the plasma of 60-70%. L-glutamine instantly nourishes lymphocytes and macrophages present in the intestine, the first defense line of our immune system.

2. Peptide bonded glutamine – In the peptide form, glutamine loses this function on the immune system. Still, it increases the percentage of glutamine found in the plasma after ingestion up to 10 times.

Taking higher doses of L-glutamine could be a better option for endurance athletes. Why? Because this way, you will have the same concentration of glutamine in the plasma as if you were taking peptide bond glutamine, plus it will stimulate your immune response.

Benefits of glutamine supplementation or high-glutamine diet for endurance athletes

The benefits of oral glutamine supplementation or a high-glutamine trusted diet for endurance athletes are numerous. These are the most significant beneficial effects of glutamine supplementation:

• Protein synthesis - During intense workouts, muscle fibers get damaged—the repairing process happens during the recovery period through protein synthesis. The muscles get repaired to be stronger and more resistant than before. Glutamine intervenes in this process as a donor of nitrogen and carbon, which are crucial for protein synthesis.

• Strengthening the immune system - Practicing sports at a very intense level puts a strain on the immune system, weakening it. Glutamine provides energy to the immune system cells, making you more resistant to upper respiratory infections and inflammation.

• Ulcer repair - Some studies have found evidence linking glutamine supplementation with faster healing of gastric ulcers.

• Prevents overtraining syndrome - there is a relationship between the permanent drop in plasma glutamine levels and the symptoms of overtraining.

• Muscle cell volumizer - Glutamine promotes the entry of water, amino acids, and other substances into muscle cells. Water is fundamental in glycogen synthesis; each gram of glycogen produced by the body binds 2.7 grams of water. That makes glutamine an excellent supplement for post-workout.

• Reduction of inflammation - Glutamine allows intestinal cells to create an effective barrier against toxins in the digestive tract. Consequently, the intensity of allergies and inflammatory processes is reduced.

• Mood improvement - Up to 80% of neurotransmitters are produced in intestinal cells. Consumption of glutamine allows these cells to have enough energy to produce serotonin, an important mood regulator. Glutamine is also a precursor of GABA neurotransmitter, which is another mood enhancer.

Tips for glutamine intake

Pre-workout – glutamine should be taken with carbohydrates. The main reason for this is to optimize performance and reduce oxidative damage induced by intense physical exercise.

Post-workout – glutamine should be taken with simple sugars and branched-chain amino acids to optimize the muscle recovery phase.

Also, glutamine intake on an empty stomach and during recovery stimulates the growth hormone secretion and improves athletic performance. To increase glutamine absorption, you can mix it with drinks rich in electrolytes. You should avoid mixing it with hot beverages or drinks with acidic PH, as it will reduce its assimilation. You can integrate glutamine with BCAAs to stimulate lipolysis and reduce fatigue in periods of reduced carbohydrate intake. A combination with HMB (amino acid metabolite leucine) can be useful to minimize catabolism during endurance training.

Foods rich in glutamine

Glutamine is most abundant in foods of animal origin, such as meat, eggs, and dairy products. This nutrient is also found in some fruits, vegetables, legumes, and soy derivatives.

The dietary sources of glutamine include:

Animal sources - meat, chicken, pork, fish, eggs, milk, yogurt, and cheese

Vegetable sources (uncooked) - beans, spinach, peanuts, barley, cabbage, and beets.

For better absorption, you should prefer raw, smoked, or seasoned foods that contain glutamine, as when cooked, glutamine degrades very fast. The consumption of some of these foods, like dairy products and soy, can be counterproductive for endurance athletes who suffer from conditions like intestinal permeability. In this case, taking glutamine supplements should be considered.


Glutamine dosage should be based on individual characteristics and needs. The optimal range for endurance athletes ranges from 4 to 10 g per day, one or two hours before meals. The recommended dosages are much higher only in the presence of conditions like traumas or pathologies related to the moderate or severe immunosuppressive state. Divide the entire dosage into several daily doses to improve absorption and reduce potential side effects.

Side effects

The use of glutamine is considered safe and well-tolerated, even in high doses. In medical practice, doses of up to 30 g per day are administered intravenously without significant side effects. This study has shown no side effects in athletes subjected to intense physical stress who took up to 30 g of glutamine per day because of glutamines' high turnover rate. It is important to mention that the studies on glutamine supplements reported the absence of significant side effects during short-term supplementation. Rarely, some transient symptoms, like abdominal discomfort and increased levels of ammonia in the blood, were reported. Further studies are necessary to define if there are any noteworthy symptoms during long-term supplementation.

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