Early gut microbiota alterations may precede food sensitization

Last Updated: 2015-03-25

By Anne Harding

NEW YORK (Reuters Health) - The gut microbiota of infants who develop food sensitization at one year of age is different from that of children who don't become food-sensitive, according to new findings from the Canadian Healthy Infant Longitudinal Development (CHILD) study.

"Within a few months after birth, there are some changes in infant gut microbiota, namely a reduced number of different species, that predict development of food sensitivity at one year," Dr. Anita Kozyrskyj of the University of Alberta in Edmonton, the senior author of the new study, told Reuters Health.

Food-sensitized infants also had more Enterobacteriaceae and fewer Bacteroidaceae at three months and one year than did unsensitized infants, Dr. Kozyrskyj and her colleagues report in the March issue of Clinical & Experimental Allergy.

Most infants with sensitization to milk and eggs at this age don't go on to develop food allergy, the researchers note in their report, but these children are at greater risk of atopic dermatitis, allergic rhinitis and asthma. Early life exposures that alter children's contact with microbes, such as cesarean birth and antibiotic treatment, have been proposed to play a role in children's food allergy risks, although studies have had mixed results.

In the current study, the researchers collected fecal samples from 166 infants from the CHILD study at three months and one year of age. All infants underwent skin prick testing for food allergens at one year.

Twelve of the infants (7.2%) were sensitized to food by their first birthday, most frequently egg or peanut. At three months of age, these children had significantly lower overall gut microbiota species richness than did the children who did not go on to develop food sensitization. By one year there was no longer a significant difference between the two groups, however.

Among the food-sensitized infants, at three months of age Enterobacteriaceae represented 46.4% of dominant microbial families, versus 17.3% for the non-sensitized infants (p=0.004). However, food-sensitized infants had fewer Bacteroidaceae than did non-sensitized infants (0.5% vs. 23.4%).

The ratio of Enterobacteriaceae to Bacteroidaceae at three months was 115.5 for sensitized infants and 1.0 for non-sensitized infants (p=0.03), while at one year the ratios were 0.31 versus 0.02, respectively (p<0.0001).

The results did not change when the researchers excluded infants who had already been diagnosed with food sensitivity at three months of age, and were independent of breastfeeding, cesarean delivery, and antibiotic use, all of which have been linked to lower diversity and richness in the gut microbiota.

"Another part of our research program is investigating pregnancy and postnatal factors that affect infant gut microbiota composition," Dr. Kozyrskyj told Reuters Health. "Knowing that some of these changes are associated with cesarean section delivery, there are some opportunities for prevention possible."

The findings also raise the possibility that the changes in microbiota may normalize towards the composition of an infant who does not develop sensitization, Dr. Kozyrskyj added, possibly with probiotics, or even by swabbing the vagina of a mother who delivered her baby by cesarean section and then swabbing her newborn's skin to "seed" normal microbiota growth, as is being done in a randomized controlled trial currently underway.

SOURCE: http://bit.ly/19l6T7u

Clin Exp Allergy 2015; 45:632-43.