Use of Isotope Dilution Methods to Investigate Glutamine Metabolism in vivo in Humans

Glutamine (Figure 8.1) represents merely 5% of bound amino acids in body protein.¹² Since mammals have the ability to synthesize glutamine, it is not an essential amino acid by conventional criteria. Glutamine has, however, gained a peculiar status among amino acids, and is now believed to play a prominent role at the crossroads of protein and energy metabolism.