Glutamine (Gln) is the most abundant free amino acid (AA) in the body with concentrations fluctuating around 500–900 μmol/L. The biological functions of Gln have been widely studied, and they have opened new targets because Gln could modulate physiological functions such as immune enhancer, muscular maintainer, nitrogen transporter, neuronal mediator, pH homeostasis, gluconeogenesis, amino sugar synthesis, and insulin release modulation. In 1990, it was identified that Gln is a conditionally essential AA, meaning that in hypercatabolic or stress conditions, the body suffers depletion in its circulating levels. Moreover, this condition is an independent risk factor of mortality, has been correlated with increase in infection rates, and length of hospital stay in intensive care units (ICU) patients. This characteristic confers the option of Gln use, meaning that through its targets, it could improve the outcome of patients who are suffering a hypercatabolic or hypermetabolic condition.
Part of the book: Superfood and Functional Food