From the Manufacturer:
L-Glutamine is a free amino acid found that is very common in the muscles of the body. Because it can easily pass the blood-brain barrier, it provides fuel to the brain which is converted to glutamic acid--an essential element for cerebral function. Bodybuilders and dieters commonly use L-Glutamine to help maintain muscle mass. Our L-Glutamine is a pure crystalline, free form amino acid. Each tablet contains 500 mg of L-Glutamine.