Erin Tucker never leaves home without multiple EpiPens, Ventolin and other life-saving medication for her son, Flynn.
The five-year-old was diagnosed with cow's milk and egg allergies when he was two months old and has since been diagnosed with allergies to tree nuts, sesame and latex as well as having developed asthma.
He has had 12 anaphylactic reactions.
"Nothing that we do is spontaneous, it requires a lot of planning," Ms Tucker said.
"If we want to go away for a weekend or do a day trip, we are constantly doing a risk assessment of how close is that place to an ambulance or a hospital that might be able to intubate him quickly.
"We pretty much have to bring all of his food wherever we go."
Ms Tucker said planning those logistics had become easier with time.
"But some of the things that don't get easier is we call the ambulance and pray to God that he is OK," she said.
Flynn's younger sister, Zoe, has also been diagnosed with allergies but Ms Tucker said they were not as extensive nor as serious.
The Tuckers think that might be thanks to Flynn.
The missing piece of the food allergy puzzle
For more than three decades, researchers have known that children from larger families are less likely to develop allergic disease, but the potential reason for that has remained a mystery.
Researchers from Barwon Health, Deakin University and Murdoch Children's Research Institute have used long-term data from the Barwon Infant Study to demonstrate how older siblings speed up the rate at which babies develop their gut microbiome, which protects them from allergic disease.
The Barwon Infant study has been running since 2010, collecting information from more than 1,000 mother-infant pairs from the Geelong region who have been recruited from birth for research into developmental milestones of childhood.
The team has used poo samples to measure babies' gut bacteria and then test whether the children are allergic to five different foods at one year of age.
The findings, published in the Journal of Allergy and Clinical Immunology, indicated participants with older siblings had a much more mature gut microbiome by the time they turned one.
"We don't yet know exactly why that's happening but what we think is probably happening is that we all share bacteria with one another all the time," said research team leader and Barwon Health paediatrician, Peter Vuillermin.
"What we could see very clearly was if kids had more siblings at a year of age … they had a decreased risk of food allergy," Professor Vuillermin said.
Director of the UNSW Microbiome Research Centre Emad El-Omar said newborns experienced a "transitional microbiome" as they came into contact with more bacterial sources.
"That's a kind of an unstable period because the baby will continue to be exposed to the environment, to other members of the family, to pets, to so many other different things," Professor El-Omar said.
"Clearly, if there are more and more members cohabiting, they will get more of a diversity of microbiome."
Professor El-Omar said Australians were increasingly aware of the impact of microbiomes and gut health on overall mental and physical wellbeing.
"I'm really, really excited about the fact that, generally speaking from my experience with the population here, there's a lot of awareness about gut health. Everybody is aware that gut health is relevant," he said.
"Thanks to all the good research that is ongoing within Australia and keeping up with what's happening worldwide, we will benefit from that tremendously over the next five years."
Scientists hope to build on findings with trial
The researchers are now recruiting more than 2,000 children across Australia and New Zealand for a clinical trial to build on the findings from the Barwon Infant Study data.
The trial will test whether a mixture of killed bacteria taken orally can protect young children from asthma and other wheezing illnesses by boosting a healthy response to viral infections.
Flynn Tucker is taking a probiotic tablet to see whether it boosts his gut microbiome and protects him from allergens.
Around one in every 10 Australian babies develops food allergies.
Ms Tucker said the family felt privileged to take part in the clinical trial.
"We're known as the allergy capital of the world," Ms Tucker said.
"It could mean that there could potentially be cures for asthma or for food allergies which would have a tremendous impact on Flynn's life and our quality of life," she said.
"And it could mean that there are families in the future that don't have the allergy experience and journey that we've had."
Professor El-Omar believes patients may eventually be able to tailor probiotic treatments to their specific allergies or issues.
"I suspect what's going to happen in the next five years or so is that we will learn a lot more about the personalisation of the intervention," he said.
"I think, with more and more knowledge, and certainly more focused kind of therapeutics, we might be able to manipulate it with consortia of appropriate microbiota that are missing.
"It's something that we can crack. I think definitely through proper clinical trials and proper choice of these probiotics, I think it is something that we can certainly make progress with."
Professor Vuillermin said the prevalence of food allergies in the Australian community was increasing.
"We know the rate of food allergy anaphylaxis, the most severe form of food allergy, has increased threefold since the 1990s.
"For many years, Australia has had among the highest rates of asthma in the world, so it's a really important public health problem and what we desperately need is prevention strategies."
