Network Health Dietitians July 08 Issue 36

short bowel syndrome
by Hannah Baker BSc ANutr and Dr Linda Thomas BSc PhD FIFST
Science Ofﬁ cer, nutritionist Science Manager, microbiologist
Short bowel syndrome: is there evidence for probiotic
beneﬁ t?
The length of the small intestine is with its permeable epithelial surface Small intestinal bacterial overgrowth
normally about 200 cm at birth, lining, is the site of maximum nutrient (SIBO)
varying from 275 cm to 850 cm in
absorption and removal of this is most Although the gut contains as
adults and tending to be shorter
likely to result in malabsorption prob- many as 1,014 microorganisms,
in women (13). Its surface area is
lems. The duodenum is not as good most of these are in the colon (12).
vastly increased by numerous villi
as the ileum and colon, however, in
The combination of its proximity to
and microvilli. Short bowel syn-
conserving ﬂ uids and electrolytes.
the stomach acid and its relatively
drome (SBS) is a malabsorption
The prognosis is better if the ileum is
rapid peristalsis means there are
problem that directly results from
conserved as it can adapt to take
much lower numbers of bacteria in
the anatomical or functional loss
over the function of the jejunum and
the small intestine (14). A common
of a signiﬁ cant length of intestine
colon.
complication of SBS is bacterial over-
(either because of surgery or due
Children with reduced absorption
growth in the small intestine (SIBO),
to a congenital defect).
of ﬂ uids and nutrients due to shorten-
and this can cause many problems
In infants, necrotizing enterocolitis
ing of the bowel are at increased risk
(see table). Increased bacterial
and congenital intestinal disorders are
of malnutrition and possible growth
deconjugation of bile in the small
the most common underlying causes,
retardation. In general, nutritional
bowel, for example, causes its rapid
whereas Crohn’s disease, tumours of
and/or ﬂ uid supplements are needed
re-absorption leaving an insufﬁ cient
the intestine, radiation and volvulus are
if less than 200 cm of the small bowel
amount for fat absorption, pos-
sibly leading to steatorrhoea and
the typical reasons in adults. Up to two
remains (1). A speciﬁ c vitamin-de-
deﬁ ciencies in fat-soluble vitamins.
patients per million in the UK receive
ﬁ ciency risk is also associated with
Pernicious anaemia may be caused
total parenteral nutrition (TPN) for SBS
removal of the ileum as Vitamin B12
by increased metabolism of vitamin
(11). Medical advances in neonatal
is the only vitamin absorbed here.
B12 by anaerobes, so that it is un-
care, surgery and TPN have improved
Loss of the ileum also results in bile salt
available for absorption. If carbo-
the prognosis for these patients, but
malabsorption, which has a laxa-
hydrates are not absorbed properly,
in consequence there has been an
tive effect on the colon and results
the abnormally high numbers of
increase in SBS incidence (15).
in bile salt depletion. The presence
bacteria in the small intestine can
The severity of SBS depends on
of an ileo-caecal valve is important,
metabolise them to produce short
which particular section of the small possibly because the viable count of
chain fatty acids. Although these
intestine is removed and how much bacteria increases greatly distal to
are normally considered beneﬁ cial
is left after resection. The duodenum, the valve.
in the large intestine, they increase
osmolarity in the small intestine and
�� thus may cause diarrhoea.
��
A build up of D-lactic acid in the
body (D-lactic acidosis) can also
result from this abnormal bacte-
��
��
rial metabolic activity in the small
��
��
intestine. In humans, L-lactic acid is
��
�� produced via an anaerobic carbo-
��
hydrate pathway with an enzyme
��
speciﬁ c for this isomer (L-lactic
��
dehydrogenase). D-lactic acid is
��
��
mainly produced in the body by the
��
intestinal bacteria or from fermented
�� foods. It is normally absent or at very
��
low levels in the blood, and is not a
��
��
problem in healthy people who can
metabolise it rapidly.
��
��
��
The rationale for probiotics in pa-
tients with SBS
�� SBS is not only life threatening, it
��
reduces a patient’s quality of life,
22 NHDmag.com July ‘08 - issue 36
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