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DESCRIPTION
Glutamine is a nonessential amino acid, which means that
it is manufactured from other amino acids in the liver; it does not have to be
obtained directly through the diet.
Glutamate (glutamic acid) is converted in the liver to
glutamine through the addition of ammonia. Therefore, glutamine is important in
ammonia detoxification. Glutamine is also useful in the brain as a
neurotransmitting substance.
Glutamine synthesis and degradation in the kidney help
regulate the body's acid-base balance and electrolyte levels. Glutamine levels
are higher in the blood than those of many other amino acids and are thought to
play an important role in removing ammonia, which is the toxic metabolite from
protein of tissues. The interconversion of glutamine and glutamate is dependent
upon adequate levels of vitamin B-6.
Low levels of glutamine may be associated with increasing
acidity and increased loss from the body of minerals such as calcium,
magnesium, sodium, and potassium. Individuals with low levels of glutamine may
be more susceptible to "Chinese Restaurant Syndrome" and need enhanced levels
of vitamin B-6 to prevent this condition when they eat MSG-laden foods.
Glutamine has been used to treat individuals with certain
types of brain biochemical problems, liver problems, and mineral deficiency
signs from the loss of potassium, sodium, magnesium, and calcium. Dr. Roger
Williams has suggested it may have value in managing alcoholism.
RECOMMENDED DIETARY ALLOWANCES
An RDA has not been established for glutamine because it
is a nonessential amino acid. Glutamine is considered a relatively safe amino
acid and is consumed in the food daily at levels of several grams. Its
therapeutic dose has been 100 to 1,000 mg. per day.
FOOD SOURCES
Glutamine is a nonessential amino acid, which means that
it is manufactured from other amino acids in the liver; it does not have to be
obtained directly through the diet.
METHOD OF ACTION
Prior to 1940, amino acids were generally regarded as
relatively-stable nutrient building blocks. In the 1940s and 50's that concept
was abandoned when it was found that the nitrogen atom in amino acids such as
aspartic acid and glutamic acid could be rapidly converted from one amino acid
carbon skeleton to another. The process by which these nitrogen atoms are
exchanged is called transamination and is dependent upon the coenzyme pyridoxal
pyrophosphate, which is derived from vitamin B-6. Both aspartic acid and
glutamic acid can incorporate ammonia, thereby resulting in the production of
asparagine and glutamine, respectively. It soon became apparent that asparagine
and glutamine are soluble, nontoxic carriers of additional ammonia in the form
of their amid groups. An active enzyme converts aspartate and ammonia to
asparagine and glutamate and ammonia to glutamine. The nitrogen in glutamine is
used in a great variety of biochemical processes, including the formation of
carbamoyl phosphate used in the urea cycle and the production of purines, which
are used in DNA and RNA.
Glutamate, glutamine, and aspartate also play central
roles in the removal of all nitrogen from organic compounds. The exchange of
nitrogen by transamination is reversible so that when the body is properly
managing glutamate and aspartate, there is the exchange of nitrogen from one
source, ultimately, from the urea cycle and the elimination in the urine as
urea. |
