The Science Behind L-Glutamine

L-Glutamine is an amino acid that has high levels in the body, especially in skeletal muscles. L-Glutamine fuels (carbon and nitrogen) many different cells in your. Your body needs glutamine so that it can produce other chemicals like glucose and other amino acids. Glutamine is found in foods and dietary supplements. L-Glutamine supplements are often used to increase muscle mass.

Sources of Glutamine and the Significance

Glutamine is in elevated quantities in animal products that include meat, dairy products and dairy by products (whey/casein protein). The percentage of glutamine varies in different foods

Beef 4.7 percent^[1]
Corn 16.2 percent^[1]
Eggs 4.3 percent^[1]
Milk products fluctuate 8.7 percent - 9.2 percent^[1]
Other meat fluctuates 4.2 percent - 4.8 percent^[1]
Skim Milk 8.08 percent^[1]
Tofu 9.1 percent^[1]
White Rice 11.1 percent^[1]

The Nurse Study included more than 70,000 women, and it showed the usual dietary glutamine intake is in the range of 19 grams of glutamine daily.^[1]

It’s believed that on occasion glutamine levels are reported too low, and glutamate levels might be higher than anticipated. This is because of the way of analyzing amino acid was historically done, with hydrolysis stimulating the converting glutamine to glutamate^[1,2].

The following study^[1,2] showed a higher value range when the results between gene sequencing and conventional methods were compared yielding differences of as much as 4 percent in the complete amino acids.^[1,2]

The Biological Importance

With some diseases or cachexia, this semiconditional amino acid, causes an increase in the biological need.^[5,6]This plentiful amino acid is found in tissue and plasma, especially muscle tissue. It has numerous biological roles such as its role as a conveyor for nitrogen between tissues beside Alanine, being a forerunner for nucleotides, controlling base/acid metabolism, and acting as a forerunner for glutathione, which is an antioxidant. It also encourages the making of L-glycine and L-citrulline.^[4]

As much as 13 percent of the glutamine that is circulating is utilized as an energy substrate via intestinal enterocytes and liver.^[5]

When intravenous glutamine or oral glutamine is given, glutamine synthesis rates will decrease.^[6,7] This can protect amino acids, which can be turned into glutamine.^[10]

The Pharmacology

The quantity of glutamine dedicated to hepatic tissue and intestinal tissue doesn’t change between food sources and supplement doses.^[8]

Cardiovascular Health

Ischemia/reperfusion is tissue that becomes damaged when there is oxygen restriction known as ischemia, and then an excess of oxygen in the tissue follows that, causing a great deal of reperfusion. In vitro, glutamine seems to protect against Ischemia in cardiac tissues.^[8].- It appears that Glutamine has the ability of reducing the damage from the ischemia/reperfusion damage right at the cellular level that might be linked to enhanced defenses fighting heat shock proteins and antioxidants ^[9].

Glutamine supplements in those with cardiac injury or who have recently undergone cardiac surgery shows its ability to be cardio protective.

Glucose Metabolism Interactions

Glutamine responds to dietary carbohydrate restrictions slowing spikes in blood glucose that cause a rise in insulin and blood glucose when responding to the eating of dietary carbohydrates.^[15]It doesn’t seem to occur as a result of a slowing in gastric emptying.^[10]

Muscles and Exercise

Glutamine is connected to in vitro through the synthesis of muscle protein and muscle homeostasis where extra results in anabolism and then prevents breakdown. When there is a deficit, it causes catabolism.^[15,16,17] This association has been found in vitro with infused glutamine.^[10,11,12]

Glutamine that is in vitro reduces Leucine oxidation rates while it increases leucine deposition. This leads to an increase in its effect in leucine in the muscle cell.

In research on healthy humans that were administered glutamine supplements, it doesn’t seem to improve the synthesis rates of the muscle protein.^[13]

Endurance Performance

Glutamine supplementation during longer cardiovascular exercise durations, with a decrease in ammonia, has seen an increase in performance,^[14]which is desirable. An oral load of 2 grams of glutamine has shown a plasma bicarbonate level increase in vivo.

By preventing a glutamine depletion during exercise that lasts for over an hour, can indirectly increase performance in relation to the glutamine depletion.

Glutamine Depletion and Sickness

Critically, glutamine has more significance. The glutamine demand goes up in the intestinal mucosa, the immune cells and the kidneys, in response to trauma, cachexia, and infection. It is common, however, for glutamine needs during these states to exceed the capacity of skeletal muscle to synthesis glutamine; this results in a reduction of the free (intra-cellular) glutamine pool in the body.^[15,16]When there is a glutamine reduction there is also a reduction in protein economy and metabolism alterations.^{[20, 21]}

L-Glutamine Side Effects

It appears that L-Glutamine is safe for most adults when it is taken orally, but to date there has not been adequate research to confirm this or to determine whether there are any side effects.

Special Precautions for L-Glutamine

If you are pregnant or you are breastfeeding avoid use as there is not enough data known.
If you have severe liver disease with confusion or difficulty thinking glutamine can make it worse so you should avoid.
If you have MSG sensitivity (Monosodium Glutamate), you could be sensitive to glutamine because glutamine is converted to glutamate.
If you suffer from a mental disorder called mania, it can make the condition worse so you should avoid use.
L-Glutamine can increase seizures in people who already suffer from seizures.
If you are being treated with any medications, do not use glutamine supplements without direction from your doctor.

Glutamine Containing HGH Supplements

References

Lenders CM, et al. Evaluation of a novel food composition database includes glutamine & other amino acids derived from gene sequencing. Eur J Clin Nutr. (2009)
Wilkinson SB, et al. Addition of glutamine to essential amino acids & carbohydrate does not enhance anabolism in young human males. Appl Physiol Nutr Metab. (2006)
Souba WW. Glutamine: a key substrate for the splanchnic bed. Annu Rev Nutr. (1991)
Response of glutamine metabolism to exogenous glutamine.
Effect of glutamine on leucine metabolism in humans.
Boza JJ, et al. Free & protein-bound glutamine have identical splanchnic extraction in healthy human volunteers. Am J Physiol Gastrointest Liver Physiol. (2001)
Khogali SE, et al. Is glutamine beneficial in ischemic heart disease. Nutrition. (2002)
Wischmeyer PE, et al. Glutamine preserves cardiomyocyte viability & enhances recovery of contractile function after ischemia-reperfusion injury. JPEN J Parenter Enteral Nutr. (2003)
Wischmeyer PE. Glutamine: the first clinically relevant pharmacological regulator of heat shock protein expression. Curr Opin Clin Nutr Metab Care. (2006)
Awad S, et al. A randomized crossover study of the metabolic & hormonal responses following two preoperative conditioning drinks. Nutrition. (2011)
MacLennan PA, Brown RA, Rennie MJ. A positive relationship between protein synthetic rate and intracellular glutamine concentration in perfused rat skeletal muscle. FEBS Lett. (1987)
Zhou X, Thompson JR. Regulation of protein turnover by glutamine in heat-shocked skeletal myotubes. Biochim Biophys Acta. (1997)
Candow DG, et al. Effect of glutamine supplementation combined with resistance training in young adults. Eur J Appl Physiol. (2001)
Carvalho-Peixoto J, Alves RC, Cameron LC. Glutamine & carbohydrate supplements reduce ammonemia increase during endurance field exercise. Appl Physiol Nutr Metab. (2007)
Stinnett JD, et al. Plasma & skeletal muscle amino acids following severe burn injury in patients and experimental animals. Ann Surg. (1982)
Griffiths RD. Outcome of critically ill patients after supplementation with glutamine. Nutrition. (1997)