Glutamic acid (glutamate) is simply converted to glutamine and is synthesized from argi-nine, ornithine, and proline. It is abundant in both animal and vegetable proteins and is found in high concentrations in the human brain. Glutamic acid, which is important to brain function, is the only amino acid metabolized in the brain. The conversion of glutamic acid to glutamine helps clear potentially toxic ammonia. Glutamic acid, with the help of vitamin B6 and manganese, is also a precursor of gaba (gamma-aminobutyric acid), an important neurotransmitter in the central nervous system. Glutamic acid helps transport potassium into the spinal fluid and is itself an excitatory neurotransmitter. (gaba, however, is inhibitory.) Glutamic acid thus has been used in the treatment of fatigue, parkinsonism, schizophrenia, mental retardation, muscular dystrophy, and alcoholism. Supplemented as L-glutamine, it penetrates the blood-brain barrier and can be used as a brain fuel. Research has shown that L-glutamine, in a dose of 500 mg. four times daily, decreases the craving for alcohol. This amino acid is now commonly used in alcoholism clinics. L-glutamine also seems to reduce the craving for sugar and carbohydrates and so may be helpful for some people in dealing with obesity or sugar abuse. It may also help in the healing of ulcers.
Monosodium Glutamate (MSG) is a single sodium salt of glutamic acid. This seaweed extract, now commonly produced chemically, may suggest the possible toxicity of glutamic acid as slightly neurologically irritating in high dosages. Some people seem to be particularly sensitive to glutamine and MSG. Otherwise, glutamine is relatively safe and is the best way to supplement this amino acid.
GABA itself has been used in the treatment of epilepsy, high blood pressure, and anxiety, as it helps in relaxation. GABA may also enhance the sex drive and reduce nighttime urination.