Deakin, Barwon Health researchers: Older siblings help protect babies from allergies

Geelong researchers have uncovered strong evidence that older siblings speed up the rate at which babies develop their gut microbiome, which protects them from allergic disease.

Erin Tucker with son Flynn, who has allergies.

Geelong researchers have uncovered strong evidence that older siblings speed up the rate at which babies develop their gut microbiome, which protects them from allergic disease.

The study, from Barwon Health, Deakin University and Murdoch Children’s Research Institute, has been published in the Journal of Allergy and Clinical Immunology.

While researchers have long known having more siblings is protective against allergic diseases and asthma, the underlying mechanism remained a mystery.

Findings from the Barwon Infant Study provide strong evidence that older siblings speed up the rate at which babies develop their gut microbiome — the collection of bacteria, yeast and fungi that live in the human gut and plays a crucial role in keeping humans healthy.

The team, led by Professor Peter Vuillermin, a paediatrician and director of research at Barwon Health, collected stool samples over the course of infancy from more than 1000 babies.

Barwon Health director of research Peter Vuillermin.

They then tested whether the children were allergic to five different foods at one year of age.

The babies had a skin prick allergy test, and if this was positive, a food challenge at Geelong hospital.

The most common forms of food allergy were egg and peanut.

The team examined DNA from the stool samples to measure the baby’s gut bacteria.

They analysed whether having siblings and owning dogs impacted how fast the baby’s gut microbiome matured; and then whether a more mature microbiome impacted the risk of developing food allergy.

Researcher Yuan Gao completed the research as part of her PhD studies at Deakin University and said the results were striking.

“Babies with older siblings had a much more mature gut microbiome by one year of age,” Dr Gao said.

“The really exciting part was that we were able to show that a more mature gut microbiome played a major role in the protective effect of siblings on the baby’s risk of food allergy.”

Prof Vuillermin said why older siblings accelerated the rate at which babies developed their gut microbiome was still being investigated.

It was possible they could be being exposed to more bacteria via their older siblings in day to day life, bolstering their immune systems, he said.

About one in 10 Australian babies develops food allergies.

Professor Vuillermin said building on the findings from the Barwon Infant Study, researchers were conducting a clinical trial, named ARROW.

“We aim to recruit over 2000 kids across Australia and New Zealand, to test whether a mixture of killed bacteria taken orally can protect young kids from wheezing illnesses – or what some would call asthma – by boosting a healthy response to viral infections,” he said.

“We will be applying for funding to also test whether the same strategy helps children with food allergies.

“ARROW is a very important study, which has been co-designed by the families and the team from the Children’s Inpatient Research Collaboration of Australia and New Zealand (CIRCAN).”

Flynn Tucker.

Torquay’sErin Tucker, whose 5-year-old Flynn is participating in the ARROW trial, said she was grateful for research like this and the Barwon Infant Study.

Flynn is allergic to cow’s milk, egg, most tree nuts, sesame and latex and also has asthma and hay fever.

He’s had 12 instances of anaphylaxis, all of which required at least one epipen and an ambulance.

“It has a huge impact on his life and our lives,” Mrs Tucker said.

“With so little known about why babies develop allergies and asthma, more research is needed.”

Originally published as Deakin, Barwon Health researchers: Older siblings help protect babies from allergies