L-Glutamine – Understanding The Science of This Amino Acid: HGH Anti Aging Blog

The amino acid L-Glutamine is an amino acid is found in high levels in your skeletal muscles and in lower levels throughout the body. Numerous cells require glutamine so that it can create chemicals the body needs such as glucose or other amino acids amino acids. Bodybuilders will often take L-Glutamine supplements to increase their muscle mass.

Glutamine Sources

l-glutamine-powder Animal products contain higher levels of Glutamine, which are found in dairy, meat. The amount of glutamine is different for different foods

Corn has the highest concentration at 16.2%^[1]
White Rice is the second highest concentration at 11.1%^[1]
Tofu has 9.1%^[1]
Milk products vary from 8.7% to 9.2%^[1]
Skim Milk has 8.08%^[1]
Beef has 4.7%^1]
Eggs have 4.3%^[1]
Other meat vary from 4.2% to 4.8%^[1]

One study involving 70,000 women showed the usual dietary glutamine intake is in the range of 19 grams of glutamine daily. This study is known as the ‘Nurse Study.’^[1]

The way amino acids were analyzed in the past was with hydrolysis, which stimulated the conversion of glutamine to glutamate,^[1,2]which led to the reporting of levels of glutamine that were too low and so glutamate levels could actually be higher than thought.

The study found that when the results between gene sequencing and conventional methods were compared^[1,2] a higher value range was seen, showing differences that were as much as 4% higher.^[1,2]

The Biological Importance of Glutamine

It has been discovered that some conditions cause a higher need for the glutamine amino acid.^[5,6]This amino acid is found in tissue, specifically muscle tissue, and plasma, and it has many different biological roles like its role as a nitrogen conveyor, controlling base/acid metabolism, being a precursor for nucleotides, or acting as a forerunner for glutathione. It is also supports L-glycine and L-citrulline production.^[4]

Up to 13% of circulating glutamine is used as an energy substrate through the intestinal enterocytes and the liver.^[5]If oral or intravenous glutamine or is used, there will be a decrease in glutamine synthesis rates,^[6,7] which can protect amino acids that are turned into glutamine.^[8]

The Pharmacology Makeup

The amount of glutamine committed to hepatic and intestinal tissue will not differ whether the glutamine comes from food sources or supplements.^[9]

Glucose Metabolism

When there are dietary carbohydrate restrictions, glutamine will react by slowing spikes that occur in your blood glucose. These spikes result in an insulin and blood glucose increase in response to you consuming dietary carbohydrates.^[10]However, this does not emerge because of a slowing in gastric emptying.^[8]

Cardiovascular Health

Ischemia tissue becomes damaged whenever a restriction in oxygen occurs, which results to a rebound of excessive oxygen in the tissue that leads to significant reperfusion. Glutamine in vitro appears to offer protection from Ischemia in the cardiac tissues.^[9].- It seems that Glutamine can lower t ischemia/reperfusion damage at the cellular level and so there is the possibility that it is linked to improved defenses that fight heat shock proteins and antioxidants ^[9].

For those who have undergone cardiac surgery, Glutamine following the surgery has shown to be protective.

Synthesis Of Muscle Protein

Glutamine is linked to in vitro through the synthesis of muscle protein and muscle homeostasis that then stops breakdown. Catabolims happens if there is a deficit.^{[11,12, 13]}This in vitro link has been seen with infused glutamine.^[8,15,16]

Glutamine that is in vitro lessens the rate at which Leucine oxidation occurs, while increasing leucine deposition so that it can be more effective in your muscle cells.

Research conducted on individuals that were healthy were given glutamine supplements, and what they found was that it did not appear to have any effect on improving muscle protein synthesis rates.^[13]

Endurance Performance

Glutamine supplementation during longer cardiovascular exercise where a drop in ammonia occurs, has played a role in increasing performance,^[14]which is exactly what you want. An oral load of 2 grams of glutamine increases plasma bicarbonate level.

When one stops glutamine from becoming used up when you exercise for more than an hour, can ultimately enhance your performance in relation to the depletion of your glutamine.

Glutamine Depletion and Sickness

Your glutamine demand increases in the the immune cells, intestinal mucosa, and the kidneys, when responding to cachexia, trauma, and infection. Often during these times your glutamine needs will surpass the skeletal muscle’s ability to synthesize glutamine. What then happens is a decrease of the body’s free (intra-cellular) glutamine pool.^[15,16]When glutamine is reduced there is a corresponding lowering of the protein and metabolism changes.^{[15, 16]}

Side Effects Linked to L-Glutamine

When L-Glutamine is taken orally, it appears to be safe for the majority of adults; however, the research is not sufficient to verify this nor is their enough data to identify side effects.

Special Precautions for L-Glutamine:

Pregnant or breastfeeding women should not take L-GLutamine as the data is lacking.
Those with severe liver disease where there is confusion/trouble thinking Glutamine should be avoided as it can make it worse.
Those with MSG sensitivity (Monosodium Glutamate) could have a glutamine sensitivity because Glutamine converts to glutamate.
If you suffer from mania, Glutamine can worsen the condition so it should be avoided.
L-Glutamine can cause an increase in seizures in those who have a seizure disorder.
If you are taking any medications, you should not use glutamine supplements without first consulting your doctor.

Resources:

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)
Awad S, et al. A randomized crossover study of the metabolic & hormonal responses following two preoperative conditioning drinks. Nutrition. (2011)
Wischmeyer PE, et al. Glutamine preserves cardiomyocyte viability & enhances recovery of contractile function after ischemia-reperfusion injury. JPEN J Parenter Enteral Nutr. (2003)
Stinnett JD, et al. Plasma & skeletal muscle amino acids following severe burn injury in patients and experimental animals. Ann Surg. (1982)
Carvalho-Peixoto J, Alves RC, Cameron LC. Glutamine & carbohydrate supplements reduce ammonemia increase during endurance field exercise. Appl Physiol Nutr Metab. (2007)
Griffiths RD. Outcome of critically ill patients after supplementation with glutamine. Nutrition. (1997)
Wischmeyer PE. Glutamine: the first clinically relevant pharmacological regulator of heat shock protein expression. Curr Opin Clin Nutr Metab Care. (2006)
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)