Source Naturals Free Form L-Glutamine Powder -- 16 oz

What the brand says

L-Glutamine, a free-form amino acid, can be converted to glutamic acid. Glutamic acid is a usable energy source for the brain, and a precursor to the important inhibitory neurotransmitter GABA (gamma-amino butyric acid). L-Glutamine also plays an important role in ammonia disposal.