WarriorFX

There are massive amounts of nutritional supplements marketed toward athletes today. Many magic-pill wonders quickly fade away as other fitness fads hit the market – each making a few dollars during their short shelf life. Others withstand the test of time; positively passing many scientific and anecdotal trials. Probably the most debated dietary supplement available is glutamine. It’s a non-essential amino acid, which means it can be synthesized in the body. The big question facing bodybuilders is whether exogenous use is necessary to build muscle and lose fat.

Glutamine is the body’s most abundant amino acid, the building blocks of proteins. Since glutamine represents 60 percent of the amino acid pool in muscle, depleted levels can affect fullness and performance. It is the amino acid most transported between organs. Plasma amino acid concentrations are around 30 percent glutamine, in healthy individuals. Clearly, a deficiency could disrupt homeostasis in the human body.

Adults are capable of producing glutamine at a rate of around 50 to 70 grams per day. However, a considerable problem with athlete’s relying on endogenous synthesis of glutamine is the modest rate at which the body can manufacture it. In the diet, glutamine represents around 5 to 10 percent of the total amino acid content in ordinary food. Someone consuming around 100 to 200 grams of protein per day is expected to obtain 5 to 20 grams of glutamine.

Athletes routinely engaged in strenuous and sustained exercise will increase their metabolic need for glutamine. A deficiency becomes greater when a person eats an acidic diet in conjunction with demanding exercise.

For optimal performance and health, athletes must maintain an appropriate acid-base balance in the body – to avoid metabolic acidosis. To neutralize the drop in pH, bodily processes begin breaking down muscle tissue for glutamine to supply a blood-buffering effect. Lung and brain tissue also produce glutamine, but skeletal muscle is the most readily available source for the blood stream. Additionally, the body can grab calcium salts from bone to provide an alkaline base. Accelerated glutamine losses adversely affect exercise performance by weakening bones and muscular contractions, in addition to encouraging muscle cramping. Supplementing with heavy loads of exogenous glutamine can help offset acidic conditions in athletes.

Certain dietary changes can help buffer blood pH – and spare endogenous glutamine supplies. Examples of acidic foods to eat in moderation include: wine, coffee, cereal grains, corn, beans, legumes, nuts, meats, fish, eggs, dairy and salt. Vegetables and fruits are largely alkaline; exceptions include: plums, prunes and cranberries. Bodybuilders and powerlifters often eat a lot of acidic foods for their protein content, such as meats, eggs and dairy products. This dietary practice further puts the spotlight on supplemental glutamine support.

Excessive trauma from training or injury increases glutamine demands in the body. Many researchers have illustrated the advantages of dietary glutamine in patients with severe burn injuries, an extremely catabolic state. A 2003 study reviewed glutamine’s effects on patients suffering from burns between 50 to 80 percent of their body surface. Researchers revealed a significant increase in plasma glutamine levels with 0.35 grams of glutamine per kilogram of bodyweight, per day. The treated group experienced reductions in infection rate, length of hospital stay and overall cost in medical care. Intravenous administration can always normalize plasma glutamine concentrations for intensive care unit patients. Oral administration is less conclusive in clinical settings.

Glutamine is a major contributor toward healthy immune system functioning, where it is used as an oxidative substrate in cells. It has been shown to increase growth hormone production, a powerful messenger for stimulating repair and growth in the human body. Depleted blood glutamine is one marker for diagnosing overtraining syndrome and an athlete’s risk for developing upper respiratory tract infections. Shortages of glutamine can cause athletes to suffer from overtraining syndrome and increase their likeliness of infections.

Similar to the immune system, glutamine is also a major fuel for cells lining the small intestine. Supplementation can help sooth stomach irritation and promote a healthy balance of bacteria in the digestive tract. Furthermore, glutamine can help lower levels of interleukin-8, an indicator of inflammation, in the lower intestine – if sufficient amounts are ingested in order to reach the area. Glutamine is considered essential for intestinal health.

Some literature suggests that ingesting glutamine can beneficially influence insulin action, glucose disposal and fat oxidation – with potential for treating insulin resistance. In a 2006 study, researchers found improved insulin sensitivity in multiple trauma patients receiving 0.4 grams of glutamine per kilogram, per day. This is good news for bodybuilders using glutamine while trying to control glucose during fat-loss programs. There is evidence that consuming protein and glutamine will result in more efficient glycogen uptake than consumption of a pure carbohydrate meal alone.

Glutamine does penetrate the blood-brain barrier. It has been used in alcoholism clinics to decrease cravings for alcohol. Glutamine has also been reported to decrease sugar cravings.

In 2007, the Society of Critical Care Medicine published a paper reviewing nearly 40 studies and 30 years of research, called “Exogenous Glutamine – Compensating a shortage?” Researchers concluded that “all pieces of information fit the hypothesis of an increased need for glutamine during severe metabolic stress.” Normal concentrations of glutamine are required for the body to fight off infections and traumatic stress. Dietary glutamine is required for the body to maintain normal levels. Strength and endurance athletes, undergoing exhaustive training, are likely to benefit from augmenting their food intake with glutamine supplements.

Charles Poliquin, a prominent authority in strength training, is well-known for recommending glutamine to his athletes. For some, he has reportedly suggested to consume “as much glutamine as you can afford.” In an interview with Zach Marcy, he stated: “Recent scientific research has demonstrated that consuming glutamine following exercise can accelerate muscle glycogen resynthesis and glutamine levels, which are critical in the prevention of overtraining, and the creation of an anabolic environment. I recommend ingesting 0.33 grams per kilogram; so for a 90 kilogram man, that would be 30 grams. If someone has a higher percentage body fat, I up the glutamine and reduce the carbs.”

In a 2005 interview with Poliquin, William Llewellyn had him further explain how he prescribes the use of glutamine: “When a guy can’t gain weight, a quick cure is 80g of glutamine per day, for a few days. It helps them repair the gut lining so they can absorb food better. I actually like glutamine. I consider fat as anyone with more than 10 percent body fat. Until they get to 10 percent, I only use whey protein, glycine and glutamine post workout. If they get over 10 percent, we start using glutamine. No carbs if you are fat.”

It’s important to note: glutamine generally has poor solubility in water and is sensitive to heat. Luckily, several glutamine products on the market have increased its ability to dissolve in water. Regardless of the product, keep it stored in cool environments. Since dietary glutamine is quickly absorbed in the first pass by the gut and liver, large doses may be required to expect an ergogenic effect.

Although clinical studies do support glutamine supplementation in critically ill patients, many discredit its use as a performance-enhancing substance in healthy adults. Many athletes swear it’s useless – “a waste of a bodybuilder’s hard-earned money.” However, on the flip side, a lot of anecdotal evidence supports the use of glutamine as part of an intense bodybuilding program – from recreational bodybuilders to experienced strength coaches. It may be accurate to suggest glutamine is most helpful during extreme training that flirts with overtraining conditions. More clinical research is needed to examine the effects of exogenous glutamine use in heavily trained subjects, to include those training while restricting energy intake or adhering to specific macronutrient ratios.

It’s important to note: glutamine generally has poor solubility in water and is sensitive to heat. Luckily, several glutamine products on the market have increased its ability to dissolve in water.

Bowtell, Gelly, Jackman, Patel, Simeoni, Rennie. Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise, J. Appl. Physiol. Vol. 86, Issue 6, 1770-1777, June 1999

Bongers, Griffiths, McArdle. Exogenous Glutamine: The clinical evidence. Critical Care Medicine Supplement, Sep 2007.

Tjader, Berg, Wernerman. Exogenous glutamine – compensating a shortage? Critical Care Medicine Supplement, Sep 2007.