Glutamine is the most abundant amino acid in the body and is a precursor to the neurotransmitters glutamic acid and gamma amino buryic acid (GABA). GABA is an essential neurotransmitter in the brain and is formed in the body from glutamic acid (L-Glutamine). Its function is to calm neuronal activity and inhibit nerve cells from overfiring or firing erratically. Rather than stimulating neurons to fire, GABA inhibits neuronal activity. GABA is associated with mental states of calm and serenity, and also promotes muscle relaxation. It can also serve as a precursor to the production of glycogen and helps in stabilizing energy levels.

In addition to its potential uses in helping certain types of ADD/ADHD, extensive double blind tests have shown that L-Glutamine has the unique bility to boost growth hormone levels up to 430 percent. Growth hormone helps build and strengthen muscles and clear acid from body fluids, but starting at age 30, its production declines. This decline is associated with muscle loss (muscle breakdown is accelerated under acid conditions), increased body fat and accelerated aging. Glutamine supplements may help delay such developments.