Amino acid

Glutamic acid or glutamate can be manufactured by the body. It is a precursor of proline, ornithine, arginine and polyamines. It functions as a stimulatory neurotransmitter and can also be converted by the body into the inhibitory neurotransmitter GABA and the amino acid glutamine, which participates in the production of DNA. Glutamic acid is found in particularly high levels in the brain, for instance in the nerves of the hippocampus, its memory centre.

Researchers working with epileptic patients have found that most epileptics have decreased taurine, GABA and glycine, with increased aspartic acid and glutamic acid. An explanation for this imbalance may be that glutamic acid is not being properly converted to GABA in these patients. The vitamin B6-dependent enzyme glutamate decarboxylase makes GABA from glutamic acid. Vitamin B6 deficiency is known to be associated with seizures and convulsions.

'Chinese restaurant syndrome', the symptoms of which include headache, nausea, weakness, flushing and sweating after eating Chinese food, may be due to a high content of monosodium glutamate - a sodium salt of glutamic acid - in the food. Those who suffer from this syndrome may also have reduced levels of glutamate decarboxylate. It has been proposed that this syndrome can be prevented with vitamin B6 supplementation.

Glutamine

Amino acid

Glutamine is not found in food. It is primarily a brain fuel which can take the place of glucose. It is particularly abundant in the substantia nigra and thalamus of the brain, as well as in the blood, where its concentration is three to four times greater than all other amino acids. It is 10 to 15 times more concentrated in the cerebrospinal fluid than in the blood. In fasting or starvation states, when glycogen stores have been exhausted, large amounts of glutamine (and alanine) are released from muscle tissue and serve to shuttle amino acid nitrogen and carbon to other tissues. The carbon may be converted to glucose by the liver and made available for energy production.

In the 1960s an experiment was carried out supplementing 15 grams a day of L-glutamine to alcoholics. Compared with placebo, this was found to produce a significant improvement in control over alcohol consumption, but follow-up studies are lacking.

Glutamine also performs a major role in DNA synthesis. An influx of large amounts of glutamine may stimulate muscle protein synthesis. 60 per cent of the ammonia produced in the kidney tubules to buffer excessive urinary acidity comes from the breakdown of glutamine.

Availability of supplements: from health food stores.