Glutamine is for sure an important amino acid. Amino acids not only serve as a driving force for protein synthesis postexercise, but specific ones such as glutamine and leucine have additional properties that can help in the muscle-recovery process. Leucine, by itself, helps stimulate protein synthesis. Glutamine is also an excellent candidate for inclusion in a postworkout drink because muscle glutamine stores are depleted following heavy exercise and glutamine has been shown to play an important role in maintaining a healthy immune system.
When somebody is injured, undergoes surgery, has an infection, or is dealing with a prolonged period of stress, their glutamine levels can fall and a glutamine supplement could help. Therefore, glutamine supplementation is also beneficial even for people that are not engaged in intense physical activities.
What is glutamine?
Glutamine is the most abundant amino acid in the blood and muscle cells. It comprises more than 60 percent of the free amino add pool in muscle tissue. Glutamine is also the most nitrogen-rich amino acid, supplying 35 percent of the nitrogen that muscle cells use to synthesize proteins. It is mostly found in skeletal muscle but also resides in the lungs, liver, and stomach. It’s the primary fuel for the immune system and a secondary fuel source for the digestive system.
Glutamine is considered to be a “conditionally essential” amino acid because, although the body can synthesize it, there are times when the body’s high demand for glutamine exceeds its glutamine stores and manufacturing efforts. Several kinds of stress can dramatically increase the body’s glutamine needs. Strenuous exercise, injuries, and illnesses are the main ones.
Glutamine is required for countless functions in the human body from immune system function to liver function to gastrointestinal integrity, to name only a few.
What foods are high in glutamine?
You can increase your glutamine level naturally by adding glutamine-rich foods to your meals and snacks. The table below lists the glutamine content for a variety of foods.
|Round steak (3 ounces)
|Chicken breast (3 ounces)
|Chicken thigh (3 ounces)
|Ground beef (3 ounces)
|Ham (3 ounces)
|Sole/flounder fillet (3 ounces)
|Skim milk (1 cup)
|Mozzarella cheese (ounce)
|Cheddar cheese (1 ounce)
|Dry roasted peanuts (1 ounce)
|Lentils (1/2 cup)
|Soy milk (1/2 cup)
|Black beans (1/2 cup)
|Large boiled egg (1 large)
What are the supposed benefits of taking glutamine supplements?
- Promotes protein synthesis (helps maintain a positive nitrogen balance in muscle tissue)
- Helps prevent muscle tissue from breaking down (it is anti-catabolic)
- Aids muscle recovery
- Boosts the immune system
- Increases the production and release of growth hormones
- Helps in increasing the liver glycogen stores
- May aid in fat loss
Let us explore some of these benefits in more detail.
Glutamine promotes protein synthesis
Recent research suggests that glutamine may also promote protein synthesis by activating metabolic pathways through cell volumization (hydration of cells). Protein synthesis proceeds more quickly when muscle fibers are enlarged or swollen. Glutamine draws water and salt into muscle cells, thereby expediting protein synthesis.
Helps in increasing the liver glycogen stores
Glutamine can also promote the storage of glycogen. In a study by Bowtell and colleagues from the University of Dundee, Scotland, groups of six subjects each cycled until exhausted and were then given either a carbohydrate supplement, a glutamine supplement, or a carbohydrate/glutamine supplement. Although the carbohydrate/glutamine supplement did not promote more muscle glycogen storage than the carbohydrate supplement, it was more effective in increasing the liver glycogen stores.
Exactly how glutamine improves glycogen storage is not clear. It might somehow improve the uptake of glucose into muscle directly, or it might be that the glutamine is itself being converted into glucose and then being stored as glycogen in the muscles. The authors of the study seem to suggest the latter. Either way, this might just be one more amazing benefit of this amino acid for athletes.
Glutamine may increase growth hormone levels (GH)
Another interesting effect of glutamine is it may increase growth hormone levels (GH). One study took nine healthy subjects and fed them two grams (2000mg) of glutamine dissolved in a cola drink. Eight out of the nine subjects responded to the oral glutamine intake with a four-fold increase in growth hormone (GH) output. This study was particularly interesting because (a) the glutamine was given orally and not intravenously, as in other studies and (b) the study only used two grams of glutamine.
Most studies that showed any effect on GH used very large doses and were given directly into the veins of the poor participants. That only two grams of glutamine taken orally had such an effect of GH bodes well for the use of glutamine by athletes. Whether or not a short spike in GH will lead to a new muscle is another question, however, and in truth, short-lived spikes in GH in healthy young athletes do not appear to affect muscle mass.
Boosts the immune system
At one time it was believed that carbohydrates provided all of the necessary nutrition to support immune system function. It is now well documented that glutamine is also an important nutrient for cells of the immune system. During prolonged exercise, glutamine levels are depleted. Within twenty-four hours, glutamine levels usually return to normal, assuming the athlete is consuming a healthy diet.
However, in athletes who train intensively, glutamine levels may be chronically low. Because of the relationship between glutamine and immune system function, these athletes may be more susceptible to upper respiratory tract infections. One study reported that 73 percent of athletes with infection had glutamine levels below normal. This suggests that athletes who train intensively would benefit from glutamine supplementation. Researchers have demonstrated that supplementation could increase baseline levels of glutamine. It has also been demonstrated that when protein is taken following exercise, the normal drop in glutamine can be prevented.
Because of its potential effects on the immune system, the use of glutamine may also help to prevent overtraining syndrome (OTS) in athletes who train too long and too hard. Several studies have suggested glutamine levels may be indicators of OTS.
Glutamine may aid in fat loss
Some research hints that supplementing with glutamine can curb the desire for sugary foods — an excess of which leads to fat gain. For these reasons, glutamine may turn out to be an important amino acid for dieters and exercisers who need to curb their desire for fat-forming sweets. Between 200 mg and one gram of glutamine can be taken with water 30 minutes before meals to lessen the desire for sugary foods.
Which glutamine supplement to choose?
Glutamine can be added to your diet in one of two ways:
(1) As a glutamine supplement (standalone supplement)
Designed to provide a potent dose of pure glutamine directly into your muscle cells, glutamine supplements come in tablet, pill, capsule, or powder form. However, the powder can be added to your post-workout drinks, which will in turn speed up the recovery process, repair muscle tears and tissue, relieve soreness, and help with fatigue after a grueling workout. If you go for powder, be sure to take it with a cold liquid, not hot, as heat destroys glutamine.
(2) As part of a protein supplement
Look for added glutamine in the list of ingredients. Protein supplements come in powder, capsule, tablet, or liquid form.
Are there any side effects of glutamine supplementation?
Studies have shown that short-and long-term glutamine supplementation is safe in humans. Oral doses of glutamine as high as 0.3 grams per kilogram of body weight have been administered with no evidence of toxicity.
However, people with liver or kidney disease should not supplement with glutamine, however, because it can aggravate these conditions and interfere with their treatment.
How to take glutamine?
Studies have shown that 100 to 200 milligrams per kilogram of body weight of glutamine each day is sufficient for athletes and that chronic usage is important.
When to use glutamine supplements?
Glutamine supplements are needed most during the recovery period when your body has depleted its levels and is in danger of falling into a catabolic state. Having sufficient glutamine in your system will enable your body to recover faster and more effectively.
It could also be appropriate to top up your glutamine level before training, ensuring that your body doesn’t run short during your workout.
How much glutamine you need will depend on the level of activity you undertake. Always check the label for the recommended dose, and consult a medical professional before use, particularly if you are diabetic.
Do you need a standalone/separate glutamine supplement?
No! Many brands of meal-replacement products and protein supplements contain glutamine, making separate supplementation totally unnecessary. Every better whey protein already contains glutamine (and all other necessary amino acids) in a sufficient dose. For example, 100% Whey Gold Standard from Optimum Nutrition (the best whey protein on the market) contains 4 g of glutamine per serving. This more than satisfies all your daily needs for L-glutamine. Or even better, Kaged Muscle Kasein Protein Powder contains even 5.0 grams of glutamine & glutamic acid per serving (1 scoop or 35.6 g).
Closing thoughts: How does glutamine help bodybuilders?
Maintaining a positive nitrogen balance and high glutamine levels is crucial to building muscle. Your body will try to keep a constant level of glutamine in the bloodstream. But when you work out, your muscles release glutamine into your system. If your body does not have sufficient storage for your workout needs, it will take its supply from the glutamine stored in your muscles, pushing your body into a catabolic – muscle-consuming – state. Glutamine supplements are designed to prevent this from happening – providing the body with all the glutamine it needs during periods of physical stress.
While supplementation with glutamine dearly has its benefits, it can’t deliver on the claims commonly used to sell it, which revolve around building more muscle. Needless to state, no one has ever exploded with muscle from the simple addition of glutamine to the diet. There are no studies to indicate that supplementation with glutamine helps healthy, well-fed adults build more muscle. You only see these effects in diseased or underfed people and animals. Therefore, there is no clear evidence that glutamine directly increases strength, muscle size, or performance. However, glutamine gets a thumbs up as a general health-improving supplement that appears to have applications for athletes.