Published: 08-08-2013 00:00 | Updated: 29-10-2014 10:56

Caesareans weaken gut microbiota and increase risk of allergies

Children who came into the world by Caesarean section are more often affected by allergies than those born in the natural way. The reason for this may be that they have a less diverse gut microbiota, according to a study presented in the scientific journal Gut.

The researchers from Linköping University, Karolinska Institutet, the KTH Royal Institute of Technology, Örebro University and the University of Glasgow have followed the gut microbiota development in 24 children in the provinces of Östergötland and Småland in Sweden.

Those children that were delivered by Caesarean section had a less diverse gut microbiota during their first two years of life than those born vaginally. Particularly clear was the low diversity among the group Bacteroidetes, which, according to earlier observations of the research groups, are particularly linked to protection against allergies. Thus, these children may run greater risk of developing allergies, but diabetes and irritable bowel syndrome are also more common among children born by Caesarean.

"Sometimes Caesarean sections are necessary. But it is important that both expectant mothers and doctors are aware that such a delivery may affect the child's health," says Maria Jenmalm, professor of Experimental Allergology at Linköping University.

The gut microbiota may be regarded as the biggest organ in the body. In the small and large intestines of an adult, there are at least ten times more bacteria than there are cells in the body. The number of species in a human exceeds 100. They use the nutrients in what we eat and in return for the food they provide a range of services. For example, some of them produce antibiotic-like substances which can kill off other unpleasant bacteria.

"One condition for these new insights into this fascinating universe of bacteria is the recent advances in biotechnology. With modern DNA sequencing and computer analysis methods we can determine the species composition in hundreds of samples at the same time, and even get an idea of what characteristics the bacteria have," says Anders Andersson, researcher in metagenomics at the KTH Royal Institute of Technology and Science for Life Laboratory.

Study co-author from Karolinska Institutet was Professor Lars Engstrand, also affiliated to Science for Life Laboratory.


Decreased gut microbiota diversity, delayed Bacteroidetes colonisation and reduced Th1 responses in infants delivered by caesarean section.
Jakobsson H, Abrahamsson T, Jenmalm M, Harris K, Quince C, Jernberg C, et al
Gut 2014 Apr;63(4):559-66