So What is MSG?
MSG is short for monosodium glutamate and it is the sodium salt of glutamic acid. Glutamate is an amino acid found naturally in all living cells as well as many foodstuffs. The human body produces about 40 grams of glutamate a day and this is where newborn babies who are breast fed get their version of "MSG" as human breast milk contains ten times more glutamate than cows milk. No wonder it tastes soo good :)
In neuroscience glutamate is an important neurotransmitter that plays a key role in long-term potentiation and is important for learning and memory. Glutamic acid is in a class of chemicals called excitotoxins, which are substances that overstimulate neurotransmitters (such as glutamate) to the point of cell damage, otherwise known as "excitotoxicity."
A source of debate among scientists is what effects excitotoxins may or may not have on the central nervous system and brain related disorders such as Altzheimer's disease. The results of animal testing has raised the question of whether or not MSG or other glutamates can harm the nervous system.
In humans, proteins are broken down by digestion into amino acids which serve as metabolic fuel for other functional roles in the body. The naturally occuring glutamate found in foods is called "bound" glutamate and it is the good glutamate. The bad glutamate is known as "free" glutamate and it is obtained in a factory by various processes, then modified or fermented and refined to what is known as monosodium glutamate.