Low-birth-weight babies appear to be at significantly
higher risk of developing irritable bowel
syndrome (IBS) in later life, Norwegian researchers
report.
IBS is a chronic bowel
ailment characterized by cramping, bloating,
gas, diarrhea and constipation.
Now, the new study finds that "restricted
fetal growth significantly affected susceptibility
to IBS later in life," according to lead
researcher Dr. May-Bente Bengtson, from the
department of medicine at the University of
Oslo.
She added that "the rate of IBS was
significantly higher in women compared with
men, and [the] genetic contribution appeared
to be important for IBS among females,"
she said.
The report was published in the Sept. 27
online edition of the journal Gut.
In the study, Bengtson's team tracked the
health of 3,334 twin pairs, 1,250 of whom
were identical twins. The twins filled in
a questionnaire about their health, including
whether they had ever had IBS. The data were
then matched with their weight at birth.
Among all the twins, the rate of IBS was
5.4 percent, about one in 20. However, the
IBS rate among women was 7 percent, compared
with just 3 percent among men, the researchers
found.
http://digestive.niddk.nih.gov/ddiseases/pubs/ibs_ez/
Furthermore, the risk of developing IBS was
2.5 times greater among those whose birth
weights were below 1,500 grams (3.3 pounds)
compared with those weighing more than 2,500
grams (5.5 pounds) at birth. The risk was
generally higher for the lower-weight baby
of the twin pair, the researchers found.
Bengtson's team also found that babies who
weighed less than 1,500 grams tended to develop
IBS symptoms some 7.7 years earlier compared
with babies weighing more than 1,500 grams.
"Like other twin studies, we have shown
that restricted birth weight, when below 2500
grams, increases the risk of morbidity, and
the risk increases with decreasing birth weight,"
Bengtson said. "Convincing evidence exists
to suggest that restricted development of
specific fetal organs could predispose [individuals]
to other chronic diseases like cardiovascular
heart disease, non-insulin diabetes and hypertension."
The average age of IBS onset was similar
for both men and women, with the first signs
of the illness appearing at about the age
of 18 in men, and a year earlier in women.
In addition, the likelihood of IBS was stronger
among the identical twins, suggesting that
genetic factors play a key role in the illness.
Growth of the bowel is a dynamic process
that is ongoing at birth, Bengtson noted.
She speculates that a "lack of [fetal]
nutrition might disturb the development of
the gut and the nervous system, and thereby
cause symptoms of IBS, like abdominal pain,
bloating and disturbed defecation," she
said.
One expert said the connection between IBS
and low birth weight is a new finding, but
needs explaining.
"There is one question regarding their
interpretation of results -- is this a genetic
effect or is this a result of parental concern
over a twin who weighs significantly less
than the other twin?" said Dr. Charles
Gerson, a clinical professor of medicine at
Mount Sinai School of Medicine, New York City.
For example, parents might feed a lower-weight
twin differently than they do the larger twin,
he said.
The important role of genes in IBS in twins
is already known, Gerson said, but "interpretation
of data in IBS is always confounded by psychosocial
variables," he said.
