According to the study, published in the journal Clinical and Experimental Allergy, infants who have less variety of microbiota in their gut at three months may be at greater risk of sensitisation to certain foods such as peanuts, milk or egg at the age of one.
While most infants with food sensitisations will not necessarily go on to develop allergies, they are more likely to experience eczema, allergic rhinitis or asthma.
Lead author Meghan Azad of the University of Manitoba said: "Ultimately, we hope to develop new ways of preventing or treating allergies, possibly by modifying the gut microbiota."
The study
The researchers took faecal samples from 166 infants at the age of 3 and 12 months and analysed microbiota present using Illumina 16S rRNA sequencing. Food sensitisation was determined at 12 months by skin prick testing.
They found that 3-month old infants who had low microbiotic richness in their gut, as well as an imbalance of the bacteria Enterobacteriaceae and Bacteroidaceae (a high E/B ratio), had an increased likelihood of developing food sensitisation at 12 months.
Sensitised infants aged one year also had low levels of Ruminococcaceae.
With each quartile increase in this mixed E/B ratio, the risk of sensitisation was doubled. Conversely, each quartile increase in microbiotic richness at three months was associated with a 55% fall in food sensitisation at 12 months.
Azad et al. claim that the associations were independent of breastfeeding, caesarean delivery and antibiotic use, which are all known to reduce gut microbiota richness and diversity.
The study excluded infants with a prior food allergy diagnosis, suggesting that the microbiota differences occurred before the sensitization developed. However, the scientists have called for more research to prove a causal effect.
“Our findings suggest that gut colonization during infancy may influence the development of food allergy and atopic disease and could present novel targets for intervention,” says the study.
The implications
The study is part of a wider project called the Canadian Healthy Infant Longitudinal Development (CHILD) Study, which will collect data from over 2,500 newborn infants with the aim of determining the complex interplay of genetic and environmental factors involved in food allergies.
Co-author Anita Kozyrskyj said: "At the end of the day, we want to know if infants who show changes to normal gut bacteria composition will go on to develop food or other allergies, or even asthma."
The study's authors said up to 28% of pre-school children in the US are food sensitised.
Last year a team of US scientists identified that common gut bacteria Clostridia may actively protect against food allergies by encouraging the body’s immune system to prevent allergens from entering the bloodstream. The University of Chicago researchers have filed a provisional patent for its use in probiotics.
Source: Journal of Clinical and Experimental Allergy
Published online ahead of print, March 2015; vol 45, iss 3, pp 632–643, DOI: 10.1111/cea.12487
“Infant gut microbiota and food sensitization: associations in the first year of life”
Authors: M. B. Azad, A. L. Kozyrskyj et al.