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Good
Bacteria May
Halt Allergies in Babies
NEW
YORK (Reuters Health) - Giving soon-to-be mothers and newborns
doses of ``good'' bacteria may help prevent childhood allergies,
new research suggests. The findings are preliminary, but allergy
experts say they offer the first good evidence that harmless bacteria
can train infants' immune systems to resist allergic reactions.
Researchers
in Finland used a type of bacteria found naturally in the gut--called
Lactobacillus rhamnosus--to try to prevent allergy development
in at-risk infants. Cultured bacteria that can potentially promote
health are called probiotics. Such cultures are found in certain
foods like yogurt and cheese.
In this case,
Dr. Marko Kalliomaki and his colleagues at Turku University Hospital
gave a group of pregnant women probiotic capsules every day for
a few weeks before their due dates. For 6 months after delivery,
women who breast-fed continued on the probiotics, while bottle-fed
infants were given the treatment directly. All of the babies were
considered to be at high risk of developing allergies because
a parent or sibling was affected.
By the age
of 2 years, 35% of the children (46 of 132) had developed allergic
eczema, a condition in which the skin becomes irritated, red and
itchy. But children who had received probiotics were half as likely
to develop the skin condition, according to findings published
in the April 7th issue of The Lancet.
This cut in
eczema risk is the ``most spectacular, single result'' to come
out of studies on preventing allergic disease, Dr. Simon H. Murch
of Royal Free and University College School of Medicine in London,
UK, said in an interview.
However, Murch
stressed, the study was small, and the probiotics showed effects
only on eczema. It is too soon to tell whether they may ward off
asthma and other allergies.
Exactly why
friendly gut bacteria might protect against allergies is unclear,
but Murch said the effect may be an ''extension of the hygiene
hypothesis.''
This hypothesis
holds that the worldwide growth in allergic disease is in part
due to our increasingly sterile surroundings. When babies are
exposed to germs early on, some experts suggest, their immune
systems are steered toward infection-fighting mode--and away from
the tendency to overreact to normally benign substances. Support
for this idea comes from studies showing that infants who have
more colds and other infections have lower asthma rates later
in life.
The results
of this study suggest that intestine-dwelling bacteria may also
play an important role in pushing the immune system away from
allergic reactions, the Finnish researchers explain.
But how gut
bacteria might do this is unclear, noted Dr. Andrew Liu, a pediatric
allergy specialist at National Jewish Medical and Research Center
in Denver, Colorado. Also unknown, he told Reuters Health, is
whether these friendly bacteria or infection-causing germs are
more important in cutting allergy risk.
Still, Liu
said the findings are ``quite exciting,'' in part because probiotic
treatment seems harmless.
And although
the treatment has so far shown effects only on eczema, Liu noted,
eczema is often an indicator of a child's later asthma risk.
SOURCE:
The Lancet 2001;357:1076-1079.
Reference
Source 89
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