Glutamine is the
most abundant free amino acid circulating in the blood as well as
stored in the skeletal muscles. Glutamine is a diverse amino acid that
is utilized in numerous vital functions. It is necessary for rapidly
dividing cells, including those of the gut and immune system.
It is also used
as an energy source in mitochondria,180 and is a precursor of the brain
neurotransmitter glutamate. Glutamine is also needed for
optimal nucleotide biosynthesis and protein synthesis.
The function of
glutamine in stimulating glycogen synthase, the enzyme which controls
the synthesis and storage of glycogen fuel in muscles and liver, may
provide a mechanism by which glutamine supplements promote enhanced
Glutamine is an
important fuel for some immune cells, such as lymphocytes and
macrophages, that may have specific immunostimulatory effects.
People that do
heavy exercising can lower their glutamine levels causing stress to
their body and immune systems. For that reason, supplementing
with glutamine can be important to a serious athlete, someone
challenged with muscle loss, or who wants to help maintain optimal
immune function under heavy stress. Glutamine supplements cause a
rapid rise in cellular glutamine levels and glutamine stores in muscle.