Dymatize Nutrition L-Glutamine, the free amino acid, is the single most abundant amino acid present in skeletal muscle tissue. L-Glutamine supports muscle tissue by limiting the degradation of protein through nitrogen retention, glycogen synthesis, and protein synthesis. L- Glutamine also assists in the fueling and detoxifying of the brain. Thus, L-Glutamine has been dubbed “the thinker’s amino”. L-Glutamine’s muscle and brain tissue supporting qualities have made L-Glutamine an invaluable addition to an athlete’s regimen.