Low diversity of gut bacteria in infants linked to higher risk of asthma

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 Allergy.

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. http://onlinelibrary.wiley.com/doi/10.1111/cea.12253/abstract


To top