Microbiota and infantile food allergies: an association under the microscope

A team of American researchers tried to better understand the possible causal link between the composition of the intestinal microbiota and the onset of sensitization and/or an allergy to certain foods in children under three years old

 

Food allergies can cause very sudden, virulent reactions in the organism–referred to as anaphylactic shock–which can be life-threatening in extreme cases. Early childhood is a very particular period of study: the first months of life have long-term consequences for health, in particular for the development of food allergies.

The largest study to date

More than 200 children were enrolled in a major prospective study. The composition of their early intestinal microbiota was described between the ages of three and six months and the researchers checked for any sensitization or allergy when the children reached the age of three years. Almost 40% of subjects presented with a food sensitization–predominantly to milk, and with a high proportion to eggs–and fewer than 7% recorded an allergy (principally eggs and peanuts), between the ages of nine months and three years. The study revealed that sensitization to food varies according to the ethnic origin of the child: African Americans children being more affected than the other groups. This result, which calls for additional studies, is not the most surprising: contrary to the conclusions of previous studies, the researchers did not record a difference with respect to the microbial diversity of the three groups of children (sensitization, allergy, control).

Differences in certain bacterial genera

Four genera were under-represented in children with food sensitization and four others were under-represented in those who had recorded a food allergy. Some of these bacteria are already known for their role in allergic disorders such as eczema, asthma or atopy–a genetic predisposition to develop allergies. These results highlight the protective role of certain bacteria against certain allergens. This temporal progression from bacterial colonization to sensitization/allergy of children demonstrated by the study seems to point at the composition of the microbiota as a cause of the development of their food allergies. The mechanisms at work must be elucidated and the species and strains that are important in the onset of allergies identified more precisely. But it is a first step towards preventive strategies or treatments based on modulation of the intestinal microbiota of infants.

 

Sources:

 

Savage J., Lee-Sarwar K., Gordillo J. & al. A prospective microbiome-wide association study of food sensitization and food allergy in early childhood. Allergy. 2018;73:145–152