Low gut microbial diversity could up asthma risk in infants

Low gut microbial diversity in the intestines of infants could raise the risk for asthma development, a new research has suggested.

In 2011 the results of a comprehensive survey of the intestinal microbiota of allergic and healthy children were published. In the samples from the infancy period, the degree of variation and diversity of the bacteria strains was significantly lower among those who had developed allergic eczema when they were two years old.

A follow-up study was conducted when the 47 participating infants reached their seventh birthday. By then eight of them - 17 per cent - were suffering from chronic asthma. 28 per cent had hay fever, 26 per cent still had eczema, and 34 per cent 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 one week and one month.

Principal author Thomas Abrahamsson, paediatrician and researcher at Linkoping University, said that a high diversity of gut microbiota during the first months of life seems to be important for the maturation of the immune system.

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.

Senior author Maria Jenmalm, professor of experimental allergology, said that they were 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.

The study has been published in the journal Clinical and Experimental Allergy.