cover story
Rats fed a diet devoid of nucleo- evidence pertaining to the benefits symptom scores of IBS compared to
tides showed signs of reduced of enteral and parenteral feeds placebo (15). The authors speculate
nuclear material, reduced endo- supplemented with arginine, glu- that improved gut function could
plasmic reticulum and reduced tamine or omega-3 fatty acids are be via similar mechanisms found in
ribosome numbers in hepatocytes inconclusive and inconsistent (28). animal studies, namely increased
(13). The authors conclude that Clearly there still is the potential for mucosal protein, DNA and villus
dietary nucleotides are essential for further investigation in nucleotide height.
the normal functioning of the liver supplemented feeds. A number of aspects of the im-
but overt deficiency or functional
mune systems in athletes exhibit tran-
changes were not investigated. Dietary nucleotides
sient dysfunction after prolonged,
Feeding a nucleotide supplemented There is very limited data on the
heavy exertion, effectively leaving
diet to rats has also demonstrated nucleotide content of foods in their
an open window of impaired immu-
gastrointestinal benefits. Rats with raw state let alone what happens
nity for pathogens to gain a foot-
experimentally induced ulcerative during processing. Free nucleotides
hold, increasing infection risk (32).
ileitis fed nucleotide supplemented and nucleic acids are present in
Indeed prolonged training increases
enteral and parenteral feeds show all foods of animal and vegetable
the rates of infection, particularly
accelerated healing of small-bowel origin – but the amount is largely
upper respiratory tract infections
ulcers compared with rats fed a dependent on the cell density. Thus,
(URTI) like colds and coughs (33).
standard formula (9). In another meat, fish and seeds are reported
Nutritional supplements (glutamine,
study, weaning rats fed a nucleo-
to have high nucleic acid content
omega-3 fatty acids
side-supplemented diet
and antioxidants)
saw increased villus
Nucleotides and cell generation
have been studied
height and enhanced
as countermeasures
gut maturation com-

• Every new cell requires 3 billion
to exercise-induced
pared to rats fed a nucleotides to build it’s DNA
immune changes with
standard diet (24).
• Some cells and organs in the
limited success (34).
body lack the ability to pro- This may be due to the
Human clinical studies
duce nucleotides
limitation of a single
Patients who re-
nutrient in abolishing
ceive enteral or paren-
immune suppression.
teral feeds as their sole
But human studies
source of nutrition could
have demonstrated an
potentially be a group
improvement in mark-
whose intake of nucleo-
ers of immune function
tides is minimal and in
Clearly, the human body has a with nucleotides (23).
whom deficiency symp-
requirement for nucleotides . . .
Endurance exercise
toms might manifest. It but is this requirement exogenous
has been shown to
is not clear whether this
or endogenous?
decrease salivary IgA
has been observed but
(35). Salivary IgA is the
studies in critically ill,
whilst milk, eggs and fruit have rela- first line of defence against patho-
ICU patients show that whilst enteral
tively lower amounts (2). gens causing URTI.
feeds improve nutritional deficien-
Studies of a wide range of food
cies they do not ameliorate the
Two small studies by McNaugh-
products have found that the grow-
impaired immune response (25).
ton et al., (2006 & 2007) examined
Several enteral feeds containing
ing conditions of mushrooms (29), trained males before and after a 60
so-called immunomodulators (usu-
the method of storing sardines (30) day supplementation period with
ally arginine, omega-3 fatty acids
and degree of ripening of cheese a commercially available nucleo-
and nucleotides) are available for
(31) can affect the nucleotide tide supplement, Nucell (Wyreside,
clinical use. Several have been sub-
content of foods. So even before it Preston, UK) on salivary IgA follow-
ject to clinical review with encour-
reaches our plate, a food consid- ing a two minute maximum exercise
aging results in terms of decreased
ered to be a rich source of nucleo- test (36) and a 90 minute cycle ride
infection rate (25), improvements in
tides may no longer be, depending (37). No difference was observed in
markers of immune function (23) and
on the growing, storage and pro- performance, lactate or other mark-
shorter hospital stay (25).
cessing conditions experienced. ers of physiological stress but salivary
A systematic review undertaken
IgA was significantly increased fol-
by Beale et al., (1999) has examined
Nucleotide supplements lowing the period of supplementa-
the benefits of enteral feeds, includ-
A number of studies examining
tion after both exercise trials. These
ing those that contain nucleotides.
the effects of supplemental nucleo-
results are encouraging and warrant
They concluded that whilst there
tides have also been carried out in
further investigation to show whether
was no effect on mortality, there
differing populations and for differ-
the incidence of URTI is affected.
were significant reductions in infec-
ent beneficial effects.
tion rate, ventilator days and length
A small randomised cross-over
Conclusion
of stay in hospital and the benefits
trial (n=37) of IBS sufferers found
It is clear that nucleotides are
were most pronounced in surgical
that taking IntestaidIB, a nucleotide
involved in many aspects of cellular
(26) and malnourished patients (27). based supplement (1 x 500mg cap- metabolism, growth and immune
Another review of enteral feeds sule three times daily) resulted in a function. Their precise mechanism of
has concluded that, on the whole, 4-6% improvement in three of seven
action remains to be fully understood.
12 NHDmag.com Aug/Sep ‘08 - issue 37
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