Low diversity of gut bacteria in infants linked to higher risk of
10 January 2014
A study of seven-year old children by Linköping University in
Sweden has found that those children with low diversity of gut flora
when infants are more likely to suffer from asthma at school age.
This was a follow-up to a study conducted in 2011 that surveyed
the intestinal microbiota of allergic and healthy children. It found
that the degree of variation and diversity of the bacteria strains
in infants was significantly lower among those who had developed
allergic eczema when they were two years old.
The follow-up study was conducted when the 47 participating
infants reached their seventh birthday. By then, eight of them (17%)
were suffering from chronic asthma, 28% had hay fever, 26% still had
eczema, and 34% reacted to the allergens in a skin prick test. But
it was only the asthma cases that could be connected to low
intestinal microbial diversity at the age of five weeks. The results
have been published in the journal Clinical & Experimental
The results of this study give further credence to the connection
between intestinal flora and lung health, which has previously been
demonstrated in animal studies.
“A high diversity of gut microbiota during the first months of
life seems to be important for the maturation of the immune system,”
says Thomas Abrahamsson, paediatrician and researcher at Linköping
University, and principal author of the article.
The hypothesis is that in order to function effectively, the
immune system needs to be “trained” by large numbers of different
microorganisms. In the absence of sufficient stimulation from large
numbers of different bacteria, the system may overreact to innocuous
antigens it encounters. A high gut microbial diversity has also been
shown to strengthen the barrier function of the mucous membrane.
“We are speculating that a deficient maturity of the immune
system at an earlier age and a less efficient mucosa barrier
function can open the way to certain types of viral infection that
can be linked to the development of asthma,” says senior author
Maria Jenmalm, professor of experimental allergology.
The analysis of the bacterial flora in the children's stools was
carried out using a method known as 454 pyro sequencing at the
Science for Life Laboratory, in conjunction with researchers Anders
Andersson and Lars Engstrand. This is a powerful genetic method that
identifies DNA sequences typical of different bacterial species,
including those that cannot be cultivated in the traditional way.
1. Abrahamsson T, Jakobsson H, Andersson AF, Björkstén B,
Engstrand L and Jenmalm MC. Low gut microbiota diversity in early
infancy precedes asthma at school age by Clinical & Experimental
Allergy, in print 2014.