A study has linked the development in kids of any of food allergy, asthma, eczema and rhinitis to a common factor – an unbalanced gut microbiome.
Researchers have long been intrigued by the gut microbiome in the development of allergic diseases. But this Canadian study is unique in identifying a common origin in infancy across the four separate allergic diseases. As well, it explored the composition of gut bacteria in children before and following allergic sensitization.
As each allergic disease has a separate list of symptoms, they are usually studied on their own. “But when you look at what is going wrong at a cellular level, they actually have a lot in common,” notes Dr. Charisse Petersen, co-senior author and a researcher at BC Children’s Hospital Research Institute and BC Children’s Hospital.
The study is part of the long-running CHILD Cohort Study and involved medical assessments on 1,115 children. Researchers tracked the kids from birth to 5 years of age. Five hundred and ninety-two of the children developed at least one allergy type by age 5. Their results were compared against the other 523 kids in the group – who never developed allergies.
The research team at BC Children’s finds in this and previous work that how bacteria colonizes the gut of infants is vital to immune system development. When there is not a balance between beneficial and harmful bacteria from an early age, this leads to what’s called dysbiosis. That bacterial imbalance skews the immune system toward an allergic response.
“Early life bacterial colonization is key for training the immune system and helping it to know what it should react to and what it shouldn’t,” co-senior author Dr. Stuart Turvey told the Canadian Press. Turvey, a leader of the CHILD study, is a professor of pediatric immunology.
Gut Microbiome: Bacterial Clues
“There are a lot of potential insights from this robust analysis,” says Turvey of the study published in Nature Communications. “From these data we can see that factors such as antibiotic usage in the first year of life are more likely to result in later allergic disorders.” Antibiotics are known to wipe out beneficial bacteria in the gut microbiome.
In contrast, the study team from four universities found breastfeeding for the first six months had a protective effect against allergy risk. With both factors, “this was universal to all the allergic disorders we studied,” notes Turvey.
As they tracked the children in the CHILD study, the researchers collected stool samples at ages three months and one year of age. Within those stool samples they could see a bacterial “signature.” It indicated gut microbiome imbalance in the group that would go on to develop by age 5 any of: food allergies, asthma, eczema or rhinitis.
Turvey and the team hope these insights can lead to therapies that correct infants’ gut microbiomes. “Developing therapies that change these interactions during infancy may prevent the development of all sorts of allergic diseases in childhood, which often last a lifetime,” says Turvey.
Microbiome and Peanut Allergy
Another August 2023 study zeroes in on specific gut microbiome characteristics in infants that may predict the childhood onset of peanut allergy.
The study, involving several U.S. centers, was led by Dr. Supinda Bunyavanich, an allergist-researcher at the Jaffe Food Allergy Institute at Mount Sinai in New York.
The research team monitored infants considered at risk for developing allergies. They began by examining stool samples in infancy, and then later in childhood. The team identified key differences in gut bacteria and metabolites in the child study participants who developed a peanut allergy by about age 9.
In the kids who developed peanut allergy, there was a different abundance of bacteria such as Clostridium and Bifidobacterium. In addition, metabolites like butyrate and isovalerate decreased over time in those who developed peanut allergy.
Bunyavanich says the paper, published in the Journal of Allergy and Clinical Immunology, offers insights into potential preventive strategies. These “could have a profound impact on how we address peanut allergies in children.”
While the insights hold promise of diet interventions or probiotic approaches, the lead author provides a note of caution. “Altering a child’s gut bacteria isn’t yet an immediate solution,” says Bunyavanich. “We need further research to truly harness these findings.”
The researchers say the associations between the gut microbiome features and the onset of peanut allergy are strong. But they do not yet confirm a direct peanut allergy cause.