The Preferred Fuel Source: L-Glutamine

If you were to pick a single amino acid as part of your daily supplementation, L-Glutamine would certainly be a great choice. Since glutamine makes up approximately 60 percent of the amino acids in skeletal muscle, it is no surprise that the regulation of intramuscular glutamine has significant effects on skeletal muscle metabolism. And, glutamine actually helps you store muscle glycogen, the primary fuel source for intense exercise.

To make glutamine even more attractive, the primary benefits of L-Glutamine have been found to be:

• prevention of muscle break down and support in fat loss (from increased muscle as well as increased production of human growth hormone) • support of enterocytes (intestinal lining cells) through which all nutrients are absorbed • improved or increased immune system • clarity of thought and better muscle contractions as it is the amino acid found in highest concentration in spinal and cerebral fluid.

Read on for more detailed and biochemically based explanations.

So, what is L-Glutamine?

L-Glutamine is the most abundant "free" amino acid in the body, but it is considered a "non-essential amino acid" since it can be synthesized in the body from glutamate by the enzyme "glutamine synthetase" or by oxidation from proline in the liver. However, scientists have classified glutamine as a "conditionally essential" amino acid, because under certain conditions (such as severe stress), glutamine may be needed in much higher amounts. Additionally, glutamine has been found in higher concentrations than other amino acids in vital tissues including the brain, intestinal mucosa cells, immune cells, and in skeletal and smooth muscle.

Technically, Glutamine acts as a nitrogen shuttle by picking up and dropping off nitrogen around the body. Nitrogen is an essential component of DNA (the genetic material of life) and vital for muscle building. Glutamine also converts to alpha-ketoglutarate, an essential nutrient for energy production in the Krebs cycle. What's of greatest interest is the mounting evidence that has accumulated showing glutamine's essential role in skeletal muscle maintenance, gastrointestinal function, immune health, brain function and recovery from physical stress. Inasmuch as L-glutamine deficiencies are related to physical stress, supplementation has shown to be extremely beneficial. This amino acid is readily absorbed from the intestinal tract, and has a mildly sweet taste, making supplementation easy and pleasant.

Glutamine and Skeletal Muscle

In muscle, the concentration of free glutamine appears to influence whether muscle will break down (low glutamine content) or build (high glutamine content). Athletes suffering from continuous fatigue have shown to have decreased blood glutamine concentrations that persist for extended periods of time. These decreased concentrations may hinder immune health and lead to slower recovery times following exercise and physical stress. Subjects supplementing with oral glutamine show elevated plasma concentrations of both glutamine and growth hormone, suggesting glutamine's potential benefit in terms of body composition.

Additional Benefits of L-Glutamine

Glutamine is also a major contributor to proper functioning of the intestines. By serving as an energy source for these highly active cells, many studies have demonstrated the critical role of glutamine as the predominate fuel for intestinal epithelium and its vital action in maintaining intestinal structure and function in stress-related situations. People diagnosed with irritable bowel syndrome (IBS, Crohn's disease, etc) have also reported beneficial effects by supplementing with L-Glutamine. Glutamine deficiencies also result in functional disturbances of the immune system and/or gastrointestinal system.

Patients recovering from strenuous physical activity have an increased demand for glutamine which is probably the result of increased use by the immune system and the decreased integrity of the traumatized tissue. Following stressful physical demand, amino acids become vital for the healing process. Glutamine has proven to be essential during this time because the demand may exceed that which can be obtained from muscle stores. A recent study at the Geisinger Medical Center noted that increased muscle breakdown following extreme physical activity was in part due to glutamine deficiency. From their observations the researchers concluded that glutamine supplementation will prevent muscle breakdown and enhance the healing process. Lastly, there is evidence showing glutamine to be helpful for alcohol addiction. In an early study, alcohol consumption was curbed slightly when 1,000mg of glutamine was administered orally.

Support for Immune Health

It is well understood that immune health is dependent on macrophages and lymphocytes (a type of white blood cells). Macrophages play several important roles in immune response and exhibit anti-bacterial and anti-tumor activity by secreting potent compounds such as hydrogen peroxide, superoxide and the enzyme lysozyme, while lymphocytes bolster immune status through B and T cell activation, resulting in increased glutamine utilization.

To this end, glutamine levels are very high in white blood cells; appear to be essential for normal defense function; and are vital for lymphocyte RNA & DNA synthesis. In experimental cell cultures, lymphocytes were less efficient when glutamine was reduced. When glutamine was added to the culture medium, lymphocyte reproduction significantly rebounded to a normal rate. A further study showed that lowered glutamine concentrations reduced adequate immune health underscoring the importance of supplementation for individuals whose immune status is stressed by heavy physical activity.

Support for Neurological Health

Because glutamine is one of the most abundant amino acids in cerebrospinal fluid, it readily enters the brain where it can serve as a precursor to the neurotransmitter gamma-aminobutyric acid (GABA). GABA and serotonin are vital neurotransmitters with various functions including enhanced sense of well being and calmness. In one study performed at St. Joseph's Hospital in Phoenix, researchers showed that glutamine supplementation helped to maintain amino-acid concentration in brain tissue, increased the uptake of tryptophan and enhanced synthesis of serotonin.

Safety & Side Effects

More and more research continues to show significant results with the supplementation of L-Glutamine without negative side effects even up to 60g per day for the ultra-intense training athlete.

Recommended Dosing

L-Glutamine is recommended for intense training athletes, those subject to immune toxins or weak immune systems, and post surgery and irritable bowel syndrome (IBS) patients. Normal dosing ranges from 2g per day up to 60g per day. Optimal dosing is 5-10 per day in divided doses. This is a perfect supplement for flu and cold season as well as year round. For increased GH release, take 10g L-Glutamine upon waking on an empty stomach, as well as before bed. It is also highly recommended to be taken pre and post workout.

With all the benefits glutamine offers, and available at a more than reasonable price, it only makes sense to make this one of your primary supplements. Now you can build up your immune system and enhance your physical performance, all in one super supplement.

"Lucho Crisalle, R.D., an expert in the field of nutrition and supplements is the creator of the What Works! E-Zine. To learn more and to sign up for this monthly E-Zine about nutrition, health and lifestyle management, visit http://www.ExerciseAndNutritionWorks.com and look for the green box in the upper right corner.