LE Magazine August 2003
Xylitol candies in caries prevention:
results of a field study in Estonian children.
All field studies have unequivocally reported significant
reductions in dental caries occurrence associated with the use
of chewing gum containing xylitol. No other xylitol products
besides chewing gum have so far been tested in field trials. A
five-year follow-up study with two- or three-year xylitol
consumption periods began in Estonia in 1994 with 740
10-year-old children in 12 schools at baseline examinations.
For the study, three clusters each including three to five
schools were formed on the basis of baseline caries
experience. The products were used under the supervision of
the teachers three times per day during school days but not
during weekends or during the three-month summer holiday. The
daily dose of xylitol was 5 g in all groups. The children were
examined every year in September by two experienced
clinicians. Dental caries was recorded according to WHO
criteria. After three years, all xylitol groups showed a
highly significant 35% to 60% reduction in caries incident,
compared with the corresponding control groups. The
differences between candies, between candies and chewing gum,
and between two- and three-year users in the xylitol groups
were non-systematic, indicating no trends between the groups.
The results suggest that not only xylitol chewing gum but also
xylitol candies are effective in caries prevention, and that a
school-based delivery system seems to offer a practical way to
distribute and control the use of the xylitol products.
Community Dent Oral Epidemiol 2000
Jun;28(3):218-24
Glutamine
Branched-chain amino acid
supplementation and the immune response of long-distance
athletes.
OBJECTIVE: Intense long-duration exercise has been
associated with immunosuppression, which affects natural
killer cells, lymphokine-activated killer cells, and
lymphocytes. The mechanisms involved, however, are not fully
determined and seem to be multifactorial, including endocrine
changes and alteration of plasma glutamine concentration.
Therefore, we evaluated the effect of branched-chain amino
acid supplementation on the immune response of triathletes and
long-distance runners. METHODS: Peripheral blood was collected
prior to and immediately after an Olympic Triathlon or a 30k
run. Lymphocyte proliferation, cytokine production by cultured
cells, and plasma glutamine were measured. RESULTS: After the
exercise bout, athletes from the placebo group presented a
decreased plasma glutamine concentration that was abolished by
branched-chain amino acid supplementation and an increased
proliferative response in their peripheral blood mononuclear
cells. Those cells also produced, after exercise, less tumor
necrosis factor, interleukins-1 and -4, and interferon and 48%
more interleukin-2. Supplementation stimulated the production
of interleukin-2 and interferon after exercise and a more
pronounced decrease in the production of interleukin-4,
indicating a diversion toward a Th1 type immune response.
CONCLUSIONS: Our results indicate that branched-chain amino
acid (BCAA) supplementation recovers the ability of peripheral
blood mononuclear cells proliferate in response to mitogens
after a long distance intense exercise, as well as plasma
glutamine concentration. The amino acids also modify the
pattern of cytokine production leading to a diversion of the
immune response toward a Th1 type of immune response.
Nutrition 2002 May;18(5):376-9
Therapeutic considerations of
L-glutamine: a review of the literature.
The most abundant amino acid in the bloodstream,
L-glutamine fulfills a number of biochemical needs. It
operates as a nitrogen shuttle, taking up excess ammonia and
forming urea. It can contribute to the production of other
amino acids, glucose, nucleotides, protein and glutathione.
Glutamine is primarily formed and stored in skeletal muscle
and lungs, and is the principal metabolic fuel for small
intestine enterocytes, lymphocytes, macrophages and
fibroblasts. Supplemental use of glutamine, either in oral,
enteral or parenteral form, increases intestinal villous
height, stimulates gut mucosal cellular proliferation and
maintains mucosal integrity. It also prevents intestinal
hyperpermeability and bacterial translocation, which may be
involved in sepsis and the development of multiple organ
failure. L-glutamine use has been found to be of great
importance in the treatment of trauma and surgery patients,
and has been shown to decrease the incidence of infection in
these patients. Cancer patients often develop muscle glutamine
depletion, due to uptake by tumors and chronic protein
catabolism. Glutamine may be helpful in offsetting this
depletion; however, it may also stimulate the growth of some
tumors. The use of glutamine with cancer chemotherapy and
radiotherapy seems to prevent gut and oral toxic side effects,
and may even increase the effectiveness of some chemotherapy
drugs.
Altern Med Rev 1999
Aug;4(4):239-48
Plasma-amino acid profiles in sepsis
and stress.
Sepsis has been associated with specific plasma amino acid
patterns. Sixty-five patients were prospectively investigated
as to whether these patterns are indeed sepsis specific, or
specific for metabolic stress without concomitant sepsis, or
associated with the presence of organ failure. Virtually all
aminoacid levels were decreased by 10% to 30% (p less than
0.05), whereas cystine and phenylalanine were significantly
elevated. These changes were more pronounced in severe sepsis.
Organ failure was not associated with significantly altered
amino acid profiles. No differences were found between sepsis
and stress without signs of sepsis. In addition, imminent
death was not associated with aberrant amino acid profiles. We
conclude that sepsis and metabolic stress are associated with
changes in plasma amino acid profiles, but that such changes
are aspecific and therefore poor indicators of disease
severity.
Ann Surg 1989 Jan;209(1):57-62
Glutamine: clinical applications and
mechanisms of action.
Supplementation of the conditionally essential amino acid
glutamine may be beneficial for individuals who are highly
stressed and have minimal energy and protein reserves. This
includes elderly individuals, postoperative patients,
individuals with cancer and very low birthweight infants.
Individuals who are undergoing treatment with catabolic
glucocorticoids may also benefit. Unfortunately, confusion
exists as to situations in which glutamine may be beneficial
because a clearly defined "glutamine deficiency syndrome" has
not been described as for some other nutrients. In this
review, we will discuss how glutamine affects protein
metabolism under certain stressful conditions, how it affects
intestinal mucosal integrity and how this might relate to
sepsis and systemic inflammation. We will also discuss
nutrients that are closely related to glutamine such as
glutamate, nucleotides, arginine, glucosamines, and ornithine
alpha-ketoglutarate and how and why they might be used as
substitutes for glutamine.
Curr Opin Clin Nutr Metab Care 2002
Jan;5(1):69-75
Glutamine supplementation in bone
marrow transplantation.
An increasing number of clinical investigations have
focused on supplementation of specialized enteral and
parenteral nutrition with the amino acid glutamine. This
interest derives from strong evidence in animal models and
emerging clinical data on the efficacy of glutamine
administration following chemotherapy, trauma, sepsis and
other catabolic conditions. Glutamine has protein-anabolic
effects in stressed patients and, among many key metabolic
functions, is used as a major fuel/substrate by cells of the
gastrointestinal epithelium and the immune system. These
effects may be particularly advantageous in patients
undergoing bone marrow transplantation (BMT), who exhibit
post-transplant body protein wasting, gut mucosal injury and
immunodeficiency. Studies to date indicate that enteral and
parenteral glutamine supplementation is well tolerated and
potentially efficacious after high-dose chemotherapy or BMT
for cancer treatment. Although not all studies demonstrate
benefits, sufficient positive data have been published to
suggest that this nutrient should be considered as adjunctive
metabolic support of some individuals undergoing marrow
transplant. However, BMT is a rapidly evolving clinical
procedure with regard to the conditioning and supportive
protocols utilized. Thus, additional randomized, double-blind,
controlled clinical trials are indicated to define the
efficacy of glutamine with current BMT regimens.
Br J Nutr 2002 Jan;87 Suppl
1:S9-15
Glutamine: essential for immune
nutrition in the critically ill.
Critically ill patients on intensive care units are at an
increased risk of sepsis, which is a major cause of mortality
in these patients. Recent evidence suggests that impairment of
the functioning of the immune system contributes to the
development of sepsis in such patients. In particular,
monocytes show reduced expression of HLA-DR antigen,
associated with impaired antigen presenting capability and
decreased phagocytic activity; lymphocytes show decreased
proliferation in response to mitogens and T-helper cells show
a shift in the Th1/Th2 ratio consistent with impaired
immunity. The amino acid glutamine becomes conditionally
essential in the critically ill, yet such patients frequently
have a marked deficiency of glutamine; the reasons for this
are still unclear. Glutamine is required by the cells of the
immune system both as a primary fuel and as a carbon and
nitrogen donor for nucleotide precursor synthesis. In vivo
studies have demonstrated that glutamine is essential for
optimal immune cell functioning for monocytes, lymphocytes and
neutrophils. A number of trials of patients fed by the enteral
or parenteral route have shown improved infectious morbidity
when supplemented with glutamine. However, the exact mechanism
of glutamine action in these patients remains to be
determined.
Br J Nutr 2002 Jan;87 Suppl
1:S3-8
Can glutamine modify the apparent
immunodepression observed after prolonged, exhaustive
exercise?
Glutamine is an important fuel for some cells of the immune
system. In situations of stress, such as clinical trauma,
starvation, or prolonged, strenuous exercise, the
concentration of glutamine in blood is decreased, often
substantially. In endurance athletes this decrease occurs
concomitantly with relatively transient immunodepression.
Provision of glutamine or a glutamine precursor has been found
to decrease the incidence of illness in endurance athletes. To
date, it has not been established precisely which aspect of
the immune system is affected by glutamine feeding during the
transient immunodepression that occurs after prolonged,
strenuous exercise. However, there is increasing evidence that
neutrophils may be implicated.
Nutrition 2002 May;18(5):371-5
Back to the
Magazine Forum
|