I am not posting the following article to prove or disprove anything, I just thought it was interesting:
Introduction:
L-glutamine is the
most prevalent amino acid in the bloodstream and
because human cells readily synthesize it, is usually
considered a non-essential amino acid. It is found in
high concentration in skeletal muscle, lung, liver,
brain, and stomach tissue. Skeletal muscle contains the
greatest intracellular concentration of glutamine,
comprising up to 60 percent of total body glutamine
stores, and is considered the primary storage depot and
exporter of glutamine to other tissues. Under certain
pathological circumstances the body's tissues need more
glutamine than the amount supplied by diet and
biosynthesis. During catabolic stress intracellular
glutamine levels can drop more than 50 percent, and it
is under these circumstances that supplemental
glutamine becomes necessary.1
In times of metabolic stress, glutamine is released
into circulation, where it is transported to the tissue
in need. Intracellular skeletal muscle glutamine
concentration is affected by various insults, including
injury, sepsis, prolonged stress, starvation, and the
use of glucocorticoids. Therefore, glutamine has been
re-classified as a conditionally essential amino acid.
Research demonstrates glutamine supplementation may be
beneficial when added to total parenteral nutrition (TPN)
for surgery, trauma, and cancer patients. In addition,
evidence suggests it may provide benefit for certain
gastrointestinal conditions, wound healing, critically
ill neonates, HIV/AIDS patients, immune enhancement in
endurance athletes, and prevention of complications
associated with chemotherapy, radiation, and bone
marrow transplant.1,2
Biochemistry:
L-glutamine accounts
for 30-35 percent of the amino acid nitrogen in the
plasma. It contains two ammonia groups, one from its
precursor, glutamate, and the other from free ammonia
in the bloodstream. One of glutamine's roles is to
protect the body from high levels of ammonia by acting
as a nitrogen shuttle. Thus, glutamine can act as a
buffer, accepting, then releasing excess ammonia when
needed to form other amino acids, amino sugars,
nucleotides, and urea. This capacity to accept and
donate nitrogen makes glutamine the major vehicle for
nitrogen transfer among tissues. Glutamine is one of
the three amino acids involved in glutathione
synthesis. Glutathione, an important intracellular
antioxidant and hepatic detoxifier, is comprised of
glutamic acid, cysteine, and glycine.1,2
Clinical Indications Gastrointestinal Disease:
The gastrointestinal tract is by far the
greatest user of glutamine in the body, as enterocytes
in the intestinal epithelium use glutamine as their
principal metabolic fuel. Most of the research on
glutamine and its connection to intestinal permeability
has been conducted in conjunction with the use of TPN.
Commercially available TPN solutions do not contain
glutamine, which can result in atrophy of the mucosa
and villi of the small intestine. Addition of glutamine
to the TPN solution reverses mucosal atrophy associated
with various gastrointestinal conditions.3
Research has demonstrated glutamine-enriched TPN
decreases villous atrophy, increases jejunal weight,
and decreases intestinal permeability.4,5
Trauma, infection, starvation, chemotherapy, and other
stressors are all associated with a derangement of
normal intestinal permeability. One potential
consequence of increased intestinal permeability is
microbial translocation. Bacteria, fungi, and their
toxins may translocate across the mucosal barrier into
the bloodstream and cause sepsis.6
In numerous animal studies of experimentally induced
intestinal hyperpermeability, the addition of glutamine
or glutamine dipeptides (stable dipeptides of glutamine
with alanine or glycine) to TPN improved gut barrier
function, as well as immune activity in the gut.7
Conditions characterized by increased intestinal
permeability that might benefit from glutamine
supplementation include food allergies and associated
conditions, Crohn's disease, ulcerative colitis, and
irritable bowel syndrome. A clinical study of
ulcerative colitis patients demonstrated that feeding
30 g daily of glutamine-rich germinated barley
foodstuff (GBF) for four weeks resulted in significant
clinical and endoscopic improvement, independent of
disease state. Disease exacerbation returned when GBF
treatment was discontinued.8
It has also been suggested that cabbage juice
consumption may provide benefit to patients with
gastric ulcers and gastritis, by virtue of its high
glutamine content.
Wound Healing:
The gastrointestinal tract has a large number of immune
cells along its length - fibroblasts, lymphocytes, and
macrophages. The ability of glutamine to nourish these
immune cells may account for its positive impact on the
gastrointestinal tract and immunity. Healing of
surgical wounds, trauma injuries, and burns is
accomplished in part by the actions of these immune
cells. Their proper functioning is dependent on
glutamine as a metabolic fuel for growth and
proliferation. Therefore, a depletion of intracellular
glutamine can slow growth of these cells, and
ultimately prolong healing.1 A small clinical study
conducted recently in Poland demonstrated
glutamine-supplemented TPN rapidly improved a number of
immune parameters in malnourished surgical patients
with sepsis.9
Additional clinical trials also suggest that glutamine
supplementation, as well as arginine and omega-3 fatty
acids, may promote restoration of normal tissue
function and intestinal permeability in post-operative
patients.10,11
Infection and Immunity:
Decreases in glutamine concentrations may
result in an increased rate of infection in certain
stressed patient populations. Critically ill newborn
infants frequently display protein-calorie malnutrition
due to the demands of sepsis and respiratory failure. A
study of nine critically ill infants given a
glutamine-supplemented enteral formula (0.3 g/kg
glutamine daily) for five days demonstrated a
significant decrease in infection and septic
complications (20% in the glutamine group versus 75% in
the control group).12
Endurance athletes also have decreased plasma glutamine concentrations
after prolonged, strenuous exercise. This post-exercise
glutamine depletion and associated immunosuppression
may render the athlete more susceptible to infection. A
group of 151 elite runners and rowers were given two
drinks containing either glutamine or placebo
immediately after, and two hours post-exercise, and
then asked to complete questionnaires regarding the
incidence of infection during the seven days
post-exercise. The percentage of patients
infection-free during the seven days was significantly
higher in the glutamine group (81%) than in the placebo
group (49%).13
HIV/AIDS:
HIV infection appears to induce glutamine deficiency,
resulting in muscle protein wasting, particularly in
the AIDS stage of the infection.14
Approximately 20 percent of AIDS patients also have
abnormal intestinal permeability.15
Clinical studies have demonstrated glutamine
supplementation has significant benefit in these
patients. A double-blind, placebo-controlled study was
conducted with 68 HIV-infected patients having
documented weight loss who were given a nutrient
mixture containing 14 g L-glutamine twice daily for
eight weeks. Body weight, lean body mass, and fat mass
were measured throughout the eight-week period. At
eight weeks, patients taking the glutamine mixture had
gained 3.0 ± 0.5 kg of body weight compared to 0.37 ±
0.84 kg in the placebo group. The body weight gain in
the glutamine group was primarily lean body mass while
the placebo group lost lean body mass. An additional
benefit in the supplemented group was improved immune
status as evidenced by increased CD3 and CD8 cell
counts, and decreased HIV viral load.16
In another double-blind, placebo controlled study of
AIDS patients with abnormal intestinal permeability,
glutamine supplementation (8 g daily for 28 days)
resulted in stabilization of intestinal permeability
and enhanced intestinal absorption.15
Cancer and Bone Marrow:
Transplantation Like enterocytes, rapidly
growing tumors have high glutaminase activity, using
glutamine as their main fuel source.17
Consequently, glutamine supplementation has been
controversial in cancer patients. In vitro research has
found glutamine added to tumor cell cultures increased
cellular growth.18,19
On the other hand, in vivo animal studies have not
found glutamine increases tumor growth. In fact, one
animal study demonstrated that glutamine
supplementation actually reduced tumor growth by 40
percent and stimulated natural killer cell activity.20
Research has also suggested that rapidly growing tumors can become
glutamine traps and deplete muscle glutamine and
glutathione,17 although a clinical study of 32 colon
cancer patients demonstrated colon tumors did not
extract or trap more glutamine than intestinal tissue
without tumor.21
Fluoruoracil/folinic
acid chemotherapy for colorectal cancer often causes
diarrhea. In a double-blind, placebo-controlled,
randomized trial, glutamine (18 g daily) was given to
70 colorectal cancer patients five days prior to their
first cycle of chemotherapy. Treatment continued for a
total of 15 days and intestinal permeability and
absorption were measured. When compared to baseline
values, glutamine reduced changes in permeability and
absorption induced by chemotherapy and may be of
benefit in preventing chemotherapy-induced diarrhea.22
A similar effect was seen in esophageal cancer patients
undergoing radiation and chemotherapy, but the daily
glutamine dose was higher at 30 grams daily.23
Studies of glutamine's benefit in parenteral nutrition during and
after bone marrow transplant (BMT) have yielded mixed
results. Three earlier studies demonstrated glutamine
supplementation during BMT was of some benefit in
minimizing side effects of high-dose cytotoxic
chemotherapy, namely oropharyngeal mucositis, decreased
lymphocyte counts, and hepatic veno-occlusive disease.24-26
More recent studies, however, demonstrated
glutamine-enriched TPN solutions had only limited
benefit in BMT patients, in regard to number of days on
TPN, length of hospital stay, degree of mucositis,
white blood cell counts, infection, and diarrhea.27,28
Dosage and Toxicity Numerous clinical
trials in humans demonstrate that even at high doses,
glutamine administration is without side effects and
well tolerated, even during times of physiologic
stress. Glutamine is administered orally in bulk powder
or in encapsulated form. Dosages vary greatly depending
on the clinical situation, but are in the range of two
to four grams daily in divided doses for general wound
healing and intestinal support. For critically ill
adults, cancer, and HIV patients, the dosage is much
higher, ranging from 10-40 grams per day in divided
doses. For these patients, the bulk powder form of
glutamine eases administration of large doses.
References
1. Souba WW.
Glutamine Physiology, Biochemistry, and Nutrition in
Critical Illness. Austin, TX: R.G. Landes Co.; 1992.
2. Askanazi J,
Carpenter YA, Michelsen CB, et al. Muscle and plasma
amino acids following injury: Influence of intercurrent
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3. O'Dwyer ST, Smith
RJ, Hwang TL, Wilmore DW. Maintenance of small bowel
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4. Hwang TL, O'Dwyer
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immunodeficiency virus wasting. Med Hypotheses
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Simmel A, Roth E. Availability of glutamine from
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Armstrong A, Aust JB, et al. Effects of gastrin,
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21. van der Hulst RR,
von Meyenfeldt MF, Deutz NE, Soeters PB. Glutamine
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22. Daniele B,
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24. Anderson PM,
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Oh no Mayo, I have a piss deflector over my tree, you just can't see it 
And wow! your opinion is so easily influenced Mayo. I sure don't base my decision on a few random University studies posted from the internet.. 
