Glutamine is an amino acid that doesn’t just play a role in gastrointestinal health; it also plays a vital role in muscle protein synthesis. As the most abundant amino acid, glutamine is a non-essential amino acid that can be synthesized by almost all tissues in the human body.
For this reason, researchers have experimented with glutamine and its effect on muscle recovery and exercise performance.
8 Potential Benefits of Glutamine
- Helps Repair Injuries
- Improves Strength
- Improves Muscle Recovery
- Stimulates Muscle Growth
- Improves Digestive Health
- Reduces Inflammation
- Boosts the Immune System
- Contains Antioxidant Properties
Glutamine is the most abundant amino acid in the intracellular free amino acid pool, making up 61% of all amino acids. While glutamine is a non-essential amino acid, glutamine can become conditionally essential under certain circumstances.
One of these conditions is when the body is under significant amounts of stress; for example, during times of injury or exposure to extreme temperatures. At times like this, the body’s requirement for glutamine exceeds the body’s ability to produce glutamine. Thus, glutamine must be obtained through an external source, such as food or glutamine supplements.
Dietary Sources of Glutamine
The typical diet contains around 3–6 grams of glutamine per day. The highest proportion of glutamine comes from foods such as beef, pork, seafood, organ meats, dairy products, goat’s milk, cow’s milk, yogurt, and cheese.
However, some plant-based foods also contain significant amounts of glutamine. Leafy greens like spinach and cabbage, as well as parsley and beets, contain glutamine.
It’s important to note that cooking vegetables on high heat can break glutamine down and reduce its availability. If you want to maximize glutamine content and increase bioavailability, it’s best to consume vegetables raw.
Glutamine and Immunity
Glutamine plays a critical role in the body and the immune system. Glutamine is also crucial for muscle metabolism and is a preferred energy source for cells of the intestinal mucosa and the immune system.
Glutamine is considered a conditionally essential amino acid as traumatic injury and disease can cause a rapid depletion of glutamine. When an injury occurs—something that’s considered a stress to the body—glutamine concentrations in our blood and muscles start to decrease at a rapid rate.
If our body’s need for glutamine is greater than our ability to produce glutamine, as is often the case when responding to trauma or injury, our body will break down our protein stores, such as muscle, to release more glutamine into our system.
As immunological activity decreases when glutamine supplies are low, patients with major stress injuries like burns or chronic disease should consume a high protein diet.
Glutamine for Exercise and Resistance Training
Many studies have examined the effect of glutamine supplements on body composition, muscle growth, and exercise performance. While some studies show a positive effect when taking glutamine, other studies show no benefit at all. However, glutamine may benefit athletes in ways other than physical performance.
Studies show a minimal change in glutamine levels for short-term, high-intensity exercise, but evidence suggests that glutamine levels drop-off after prolonged high-intensity exercise. Athletes may experience lower glutamine levels because prolonged exercise and periods of heavy resistance training causes a decrease in plasma glutamine concentrations.
According to research published in the Journal of Nutrition, this decrease in glutamine affects immunity and increases susceptibility to infection in athletes. However, studies show that glutamine supplements may not prevent post-exercise immune function, as glutamine levels do not fall low enough after exercise to compromise our body.
Another study published in the European Journal of Applied Physiology examined ten active males supplementing with glutamine. The study found that acute glutamine supplementation can reduce gastrointestinal permeability and damage after exercise (even at low doses).
Glutamine and Muscle Growth
While glutamine is involved in muscle protein synthesis, glutamine may not play a big enough role in the body to increase muscle mass by a significant amount.
A study conducted by the University of Saskatchewan examined the effect of glutamine supplements on resistance-trained athletes aged 18-24. The researchers split the athletes into two groups. One group took a glutamine supplement, while the other group took a placebo for 6-weeks before and after each training session.
The study measured the athletes’ one-rep max (1RM) for the squat and bench press, as well as their knee extension torque, lean tissue mass, and rate of muscle protein degradation.
After the study, the researchers found that both the glutamine and placebo groups increased their one-rep max squat by 30% and one-rep max bench press by 14%, increasing their knee extension torque and lean tissue muscle mass in the process.
Thus, the researchers concluded that glutamine supplements are ineffective when it comes to increasing muscle mass and strength. Despite several studies showing that glutamine offers minimal benefits on its own, a few studies indicate that glutamine might be more effective when combined with carbohydrates.
During endurance exercise, there is a marked increase in blood ammonia levels, which causes both peripheral and central fatigue. A Brazilian study showed that supplementing with glutamine and carbohydrates reduced blood ammonia levels during prolonged strenuous activity. This research indicates that there may be some benefit to supplementing with glutamine and carbohydrates together.
It’s worth noting that most athletes consume a high protein diet compared to the average person. Thus, an increase in dietary glutamine (and protein) might account for any muscle or strength gains found in studies examining the effects of glutamine on muscle soreness and recovery rates.
While some research suggests that glutamine is beneficial for strength and muscle recovery, more research is needed to solidify a position on glutamine and muscle growth.
Safety and Side Effects
People with kidney disorders should not consume glutamine supplements. Although no side effects have been reported in people taking high doses of glutamine, it’s better to be cautious.
That said, short-term low to moderate dose glutamine supplementation is safe, but there’s little information available on the effects of long-term glutamine supplementation.
Glutamine doses range from 5-45 grams per day for acute treatments prescribed for individuals with specific injuries or chronic diseases. Research suggests that a healthy glutamine dose is 3-6 grams per day, but this can vary based on the type and quantity of food consumed.
Effectiveness of Glutamine
If you’re looking to boost your gastrointestinal functioning and immune system, glutamine supplementation “might” be something to consider. However, there are other supplements that are more suitable if you’re looking at glutamine to improve muscle growth and exercise performance.
While it’s true that glutamine, in the short-term, may benefit intestinal healing and improve muscle recovery after strenuous exercise, there isn’t much research to support the idea that glutamine will increase strength or muscle mass.
If you eat a diet rich in protein, you will get enough glutamine to sustain your body, so there’s no need to add extra glutamine to your diet unless you experience serious traumatic injury or suffer from some form of chronic disease.