Glutamine is the most abundant single amino acid in the blood and in the intracellular free amino acid pool (most abundant amino acid in muscle tissue). It comprises 61% of the amino acid pool in skeletal muscle. Glutamine's unique structure, containing two nitrogen side chains, consists of 19% nitrogen - making it the primary transporter of nitrogen into the muscle cell. In fact, glutamine alone is responsible for 35% of the nitrogen that gets into the muscle cell. Glutamine literally drives muscle building nitrogen into the muscle cell where it is synthesized for growth.