Is Glutamine Supplementation Helpful or Harmful?

http://articles.mercola.com/sites/a.../glutamine.aspx

]"Numerous recent studies as well as Siegel’s Basic Neurochemistry textbook emphatically state that the major source of glutamate is from glutamine in the brain. Normally, when the brain finishes using glutamate for chemical communication between brain cells at the synapse the glutamate is taken up by surrounding glial cells and changed by the enzyme glutamine synthease into glutamine, where it is stored.

The Problem With Excitotoxins

The glutamine is then transported to the neuron and by the enzyme glutaminase, it is converted to glutamate--the potential excitotoxin. I say potential because unless it accumulates outside the brain cell it is harmless.

This is the major source of glutamate within the brain. Excitotoxins are usually amino acids, such as glutamate and aspartate. These special amino acids cause particular brain cells to become excessively excited, to the point they will quickly die. Excitotoxins can also cause a loss of brain synapses and connecting fibers. Food-borne excitotoxins include such additives as MSG, aspartame, hydrolyzed protein and soy protein extract.

... Adding large amounts of glutamine to the diet increases significantly brain levels of glutamine and, hence, glutamate.

... Likewise, recent studies have shown that high brain glutamine levels increase brain levels of free radicals and impair the ability of brain mitochondria to produce energy. When the brain produces low energy, excitotoxins, such as glutamate, become even more toxic. It has been shown that the reason for glutamine toxicity under these conditions is because it is converted to the excitotoxin--glutamate.

The major use for high-dose glutamine would be to repair gastrointestinal injury. In such cases, I would recommend short-term use only. Those with a history of the following conditions should avoid glutamine, even for short-term use:

Stroke
Neurodegenerative disease
Pregnancy
Malignancy
Recent vaccinations
ADHD
Hypoglycemia
Autism
Multiple sclerosis
Other neurological disorders

Glutamine has recently been shown to produce extreme hypoglycemia, even more so than leucine, which is known to produce fatal hypoglycemia in infants.

The reason Chinese Restaurant Syndrome is not seen with glutamine challenge is that the glutamate receptors in the lungs and esophagus are stimulated by glutamate, not glutamine. The glutamine must be converted first and this occurs primarily in the brain.

The only safe situation for glutamine use is in the vigorous athlete. Glutamine is used as a muscle fuel, so that vigorous exercise will consume most of the glutamine before it can accumulate in the brain. I would still avoid long-term use in high doses. I would caution readers to avoid excess glutamine, especially in the above named conditions and situations."

I've read Blaylock's book Excitotoxins and think he knows what he's talking about, though apparently some people are more sensitive than others. I know that I am one of the sensitive ones. I felt like absolute crap once from taking a potassium magnesium aspartate combination, but had no idea why at the time. Calcium is an excitotoxin in high quantities and I have to avoid too much of it, and make sure I take plenty of magnesium. I also avoid food dyes and MSG as well. Oddly enough though, aspartame in diet soda didn't seem to affect me, even though I now avoid it on general principal.

I've only tried glutamine a few times. One 500 mg capsule under the tongue does indeed stop a sugar craving in its tracks, but if I go over 1,000 mg in a day, I feel the same way I feel from too much calcium - awful, e.g. super depressed, teary, like a nervous wreck.