The Conditionally Essential Amino Acid. Maximum growth and proliferation of most cell types occurs with adequate glutamine stores.

Glutamine plays a key part with the branched chain amino acids (BCAA) in muscle energy metabolism and the over training syndrome of athletes. Approximately, 55% of glutamine taken up is oxidized via alpha-ketogluterate and the Kreb's cycle to form CO2 and a further 20% is incorporated into citrate, lactate, organic acids, and glucose. Most glutamine is partly metabolized to form alanine and lactate. During fever, surgery, and trauma muscle free glutamine concentrations fall. Adequate circulating glutamine is needed for mucosal healing and muscle protein synthesis; therefore glutamine may be considered “conditionally essential.” Studies suggest that providing increased oral protein intake can replete muscle glutamine concentrations.