What's Up With Glutamine, GABA, and Glutamate?

To ensure an adequate supply of glutamate in the central nervous system, the body undergoes the glutamate-glutamine cycle. EAATs -- excitatory amino acid transporters -- remove glutamate from the synaptic gap, the divide between neurons that allows the transmission of impulses. The amino acids move into glial cells, which provide support and insulation between neurons. At that point, the enzyme glutamine synthetase converts glutamate to glutamine, which is then transferred back into neurons and converted to glutamate.

The enzyme glutamic acid decarboxylase synthesizes GABA from glutamine. It is inhibitory, so when it interacts with a neuron, the neuron is less likely to release neurotransmitters. GABA interacts with ionotropic GABAa and metabotropic GABA receptors. The former interact with a negatively charged chlorine ion that flows to the neuron, while metabotropic receptors interact with a positive potassium ion that flows out of the neuron. Proteins then transport GABA into glial cells, where it is degraded by enzymes.

GABA is not available in fresh foods because it requires conversion. However, some foods increase GABA production due to its relationship with glutamine and glutamate. Foods rich in glutamine include milk from grass-fed livestock, ricotta, yogurt, nuts, and beans. Glutamate naturally occurs in parmesan cheese, mushrooms, and ripe tomatoes.

Known commercially as MSG, monosodium glutamate is a combination of sodium and glutamate used for decades in Asian cuisine. Discovered by a Japanese chemist, it is the fifth taste, or umami, because it enhances the flavor of food beyond the traditional four tastes. MSG is made from fermented cane, beets, or corn, and according to research, cooking with it reduces the sodium content of many recipes by up to 40 percent without sacrificing flavor. MSG is frowned upon in many circles, but studies generally show it is safe to consume.

Neurons use electrical and chemical signals for communication. When many neurons from the same part of the brain get excited and try to send messages all at once, this can cause a seizure. As an excitatory neurotransmitter, glutamate plays a major role in this process. Too little GABA upsets the balance between excitation and inhibition; glutamate becomes too excited, resulting in a seizure. In temporal lobe epilepsy, glutamate is released during seizures, which could explain the spread of the seizures.

Ammonia is a byproduct of many biochemical reactions and a toxin. Too much ammonia in the body, specifically the brain, can cause neurological impairments leading to edema, encephalopathy, or coma. The body's process to expunge ammonia involves detoxifying it first. The molecule alpha-ketoglutarate helps to convert ammonia first to glutamate, then to glutamine. This intricate process is reversed, and the kidneys excrete the nontoxic ammonia directly, or the liver releases it as urea.

Human growth hormone or HGH is a naturally occurring chemical that helps with muscle growth, fat metabolism, and other processes. Studies show that GABA is dual action: each action may have excitatory or inhibitory influences on the amino acid, affecting the secretion of HGH. Since GABA improves sleep quality and close to 80 percent of HGH is normally released during sleep, this may be the mechanism by which some athletes experience the most benefits.

Glutathione, a combination of glutamine, glycine, and cysteine, is a natural antioxidant. It can reduce the damage caused by oxidative stress, especially within the intestines. Inflammatory bowel diseases like ulcerative colitis and Crohn's can take their toll on the intestines, making the role of glutamine vital. The amino acid may decrease intestinal inflammatory reactions as well as stress in the intestines, while glutathione helps reduce sepsis.

Most healthy bodies make the glutamine they need, but there are times when supplementation is necessary to fulfill certain health and fitness goals. For those taking more than 1.5 grams of glutamine daily, side effects could include a rash, gas, nausea or swelling of hands and feet. More serious responses to glutamine overdose are rare, but they include hearing problems and chest pain, both of which require immediate medical attention.

The body closely controls glutamate in the brain, releasing it only when, and in the amount, needed. In the case of a stroke, for example, this controlled system falters, and the neurotransmitter floods the brain. It kills neurons through excessive excitation, and what happens is akin to a chemical spill that causes secondary damage. There are a variety of methods to help those with this type of brain trauma, including finding better ways to siphon the excess glutamate that occurs during traumatic brain injuries.