Glutamine

Nonessential Micronutrient

OVERVIEW


Summary

Glutamine is the most abundant amino acid in muscle tissue and is literally stripped from the muscles during times of stress (which includes intense exercise and/or weight training). Because this depletion can cause muscle wasting and lower immune function, glutamine is considered “conditionally essential.”

Other names for Glutamine

L-glutamine

Where to find Glutamine

Glutamine is naturally produced in our muscles. And many protein foods, such as fish, meat, and dairy products contain glutamine. It’s also found in parsley and spinach.

Most quality whey-protein supplements are fortified with glutamine. And many quality meal-replacement products contain around two grams of glutamine per serving.

PERFORMANCE BENEFITS

Why athletes use Glutamine

Athletes who participate in sports that require strength, speed, and endurance, such as football players, ice hockey players, bike racers, and skiers use glutamine to help them increase or maintain muscle mass, especially during times of intense training. Extreme endurance athletes, such as marathon runners, also benefit from glutamine supplementation because of its potential to help reduce muscle-tissue breakdown and support the immune system during periods of trauma or stress. Glutamine may prove to be beneficial any time the body deals with increased amounts of stress.

Ways that Glutamine can enhance Muscle Gain & Recovery:
  • Reduce muscle breakdown and encourage muscle growth
  • Stimulate cell volumizing, which encourages muscles growth
  • Shuttle amino acids into muscle cells to improve exercise recovery
Ways that Glutamine can enhance Longevity:
  • Enhance the functioning of the immune system

HEALTH BENEFITS

Signs of Glutamine deficiency

No deficiency conditions are known to exist.


Potential uses for Glutamine

Research indicates that Glutamine may be useful in the treatment of:

  • Catabolism (muscle wasting)
  • Infections
  • Ulcers
  • Alcohol withdrawal
  • Fatigue/Weakness
  • Depression
  • Erectile dysfunction
  • Burns
  • SIDS
  • Scurvy

DISCUSSION


More about Glutamine

Glutamine is the most abundant amino acid in muscle tissue: 60% of the free-floating amino acids in each muscle cell is made up of glutamine. But, when the rest of the body can’t get its requirements for glutamine met, it robs from the muscle cells’ storage compartments, and muscles are actually broken down. Glutamine is literally stripped from the muscles during times of stress, including intense exercise. Because this depletion can cause muscle wasting, as well as lower immune function, glutamine is thought to be “conditionally essential.”


Muscle-building potential

According to research, supplementing with glutamine — a white, chalky, odorless, slightly sweet powder — may help us maximize muscle growth and increase fat loss. Glutamine may, in fact, increase levels of growth hormone in the body, which could lead to greater muscle gains or fat loss. One study, for example, showed that just two grams of glutamine caused a fourfold increase in growth-hormone levels.

Glutamine also appears to play a significant role in protein (muscle) synthesis and improving blood sugar use, which may help significantly reduce muscle-protein breakdown. One reason is because glutamine helps maintain proper cell volume. What this means is simply that the cells become “super hydrated.”


Optimal health

Equally important to glutamine’s potential performance-enhancing benefits are its potential health-promoting capabilities. This is because intense exercise causes a dramatic rise in free radicals with a simultaneous reduction of antioxidants within the body to fight them. In fact, intense exercise has been shown to increase the incidence of infection. Infections in the upper respiratory tract have been shown to be much more likely for endurance athletes who have high training mileage and after a marathon. Fortunately, this risk for infection appears to drop significantly for athletes who supplement with glutamine.

Low levels of glutamine are common in overtrained athletes. High levels, on the other hand, have been shown to help shuttle other amino acids into muscle cells, in turn improving recovery. Overtraining is evident by decreased performance, depressed mood, and increases of infection in every type of athlete and regular exerciser.

Whole body functioning

Glutamine is involved in more metabolic processes than any other amino acid. It’s converted to blood sugar and serves as an energy source. It fuels the cells lining the intestines, and without it, these cells waste away. It’s also used by white blood cells and is important for immune function because it is a component of glutathione. Glutamine is needed in mega-quantities to maintain proper function of the immune system, kidneys, pancreas, gallbladder, liver, and the whole gut.

Brain food

Glutamine also elevates levels of glutamic acid in the body. This is significant because glutamic acid is our primary “brain food.” As such, glutamine has been shown in some cases to help improve intelligence. In addition, it’s also a neurotransmitter or messenger in our brains and may improve mental alertness, clarity of thinking, and mood.

What about glutamine peptides?

As you might expect from their similar names, L-glutamine and glutamine peptides have similar benefits, ranging from increasing protein synthesis to supporting the immune system. Yet they have fairly different properties once ingested. Glutamine peptides are actually wheat protein that has been hydrolysed (which is just a fancy word for predigested or broken down). This wheat protein has a high content of glutamine, normally around 30%, in comparison to other protein sources, such as casein and whey, which are normally in the 3 to 10% glutamine range. It’s called a peptide because the glutamine is not “free”; instead it’s bound to other amino acids with peptide bonds. For this reason, glutamine peptides are generally thought of as a more stable, superior form of glutamine, but I will cover that debate in more detail in a moment.

Here are the main differences between L-glutamine and glutamine peptides…

While glutamine peptides are normally derived from wheat and are bonded with other amino acids (as explained above), L-glutamine is “free form,” meaning it’s “free” from being bonded to other amino acids. So, is one form superior to the other? It’s generally theorized that the peptide form will increase glutamine availability, due to our digestive tract having peptide transport systems that increase absorbability and utilization of the glutamine peptides. By the same theory then, this would also make more glutamine available for muscle tissues, instead of being used primarily by other parts of the body, such as the intestines, brain, or the immune system, which also demand great amounts of this important amino acid.

However, in a recent article, Richard Kreider, Ph.D., indicated that although he accepts the suggestion that glutamine peptides may be more effective, there is no conclusive evidence that orally ingested glutamine peptides promote greater benefits than free-form L-glutamine. In fact, he suggests that one reason for the potential increase in the use of glutamine peptides in today’s more popular supplements is because it’s actually cheaper to produce and use in these supplements than the free-form L-glutamine. I find this particularly interesting considering most products that contain glutamine peptides are more expensive than those that contain simple, free-form L-glutamine. So it’s not so much a question of which form is better utilized (as this has yet to be proven by science) as it is which form is more cost effective (and tolerable, as I’ll discuss below). I’m sure the question of “which form is superior” will continue to be debated, but for now, the choice is really yours until there is more clinical evidence available to support or deny the effectiveness of either form over the other.

With the glutamine peptides being derived from wheat protein, there is a possibility it could cause stomach uneasiness. Some people feel stomach discomfort simply because they’re sensitive to or have an intolerance to gluten (the protein portion of wheat, rye, barley, triticale, and/or oats), which reacts with the small bowel lining, damaging it so some of the effective absorption surface area is lost. In fact, around 1 in 300 Americans are thought to have what’s called “gluten intolerance,” yet many are not even aware of it. Unfortunately, glutens are the highest known source of glutamine, which is one of the best nutrients for gastrointestinal health (and muscle-repair/recovery). Nonetheless, if bread, pastries, sauces, or similar wheat-produced products cause similar problems, then you know the root of your stomach upset — gluten.

Thus, if consuming glutamine peptides causes you stomach discomfort, my suggestion is to simply refrain from using it and instead try supplementing your diet with regular, free-form L-glutamine (which is normally derived from corn). As always, it’s advisable to consult with your primary doctor for a professional diagnosis if your problem persists.


In conclusion

In either form, one thing is for sure: glutamine is the most abundant amino acid in human muscle and has many important functions for people involved in sports and exercise, from increasing protein synthesis (necessary for muscle growth) to supporting the immune system. This incredible powder has also been shown in research to help reduce inflammation; control alcoholism; shorten healing time for ulcers; alleviate fatigue, depression, and impotence; promote healing in burn victims; prevent muscle wasting in people who have been chronically ill; treat schizophrenia and senility; and shorten hospital stays for cancer patients undergoing bone marrow transplants, and is routinely administered to patients suffering from trauma in European hospitals. This is one nutrient that most experts agree should be included in everyone’s nutrition plan.

NOTES ON USAGE

Amount

Research has shown two grams of glutamine may result in a significant release in growth hormone. However, more typical amounts recommended range from two to six grams per day.

Timing

While glutamine should be consumed regularly throughout the day, it’s most important to make sure it’s taken both after a workout and before bed. It may also be best to supplement with glutamine without other amino acids as it appears to compete for uptake.


Synergists of Glutamine

By increasing insulin levels, simple sugars consumed with glutamine after a workout may help shuttle glutamine into the muscle cells faster and potentially improve recovery.

Toxicity of Glutamine

No known toxicity.

Bans and restrictions

None reported.

RELATED RESEARCH

  • Castell, L.M., et al., “Does Glutamine Have a Role in Reducing Infections in Athletes?” Eur J Appl Physiol 73.5 (1996) : 488-90.
  • Castell, L.M., and Newsholme, E.A., “The Effects of Oral Glutamine Supplementation on Athletes After Prolonged Exhaustive Exercise,” Nutrition 13.7-8 (1997) : 738-42.
  • Griffiths, R.D., et al., “Six-Month Outcome of Critically Ill Patients Given Glutamine-Supplemented Parenteral Nutrition,” Nutrition 13.4 (1997) : 295-302.
  • Rowbottom, D.G, et al., “The Emerging Role of Glutamine as an Indicator of Exercise Stress and Overtraining,” Sports Med 21.2 (1996) : 80-97.
  • Sacks, G.S., “Glutamine Supplementation in Catabolic Patients,” Ann Pharmacother 33.3 (1999) : 348-54.
  • Shabert, J.K., et al., “Glutamine-Antioxidant Supplementation Increases Body Cell Mass in AIDS Patients with Weight Loss: A Randomized, Double-Blind Controlled Trial,” Nutrition 15.11-12 (1999) : 860-4.
  • Wilmore, D.W., and Shabert, J.K., “Role of Glutamine in Immunologic Responses,” Nutrition 14.7-8 (1998) : 618-26.