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Katie Allen’s young patients are often surprised to discover that, like them, she has food allergy and carries an EpiPen.
But unlike her patients, Katie developed the condition as an adult. After the birth of her first child, she noticed whenever she would devour her beloved peanut butter sandwiches, her throat started swelling. “This started getting worse every time I ate it. I’d eat some, then have this really swollen throat, then I would start to drool,” she says. “I went to get some tests and they said I had adult-onset peanut allergy, which I didn’t even know existed.”
The paediatric gastroenterologist and allergist, who is a world-leader in food allergy research, can empathise with her patients and provide advice based on her team’s research.
This research has begun unravelling the mystery behind the rising food allergy epidemic in the modern world. Her findings could potentially help prevent allergy in millions of children worldwide.
When Katie first immersed herself in food allergy research a decade ago, she says there was a perception rising food allergy rates were a myth or a media beat-up. But her research has proven otherwise, with her team the first to confirm the rising allergy epidemic in Australia.
About five per cent of Australian children have a food allergy. But Melbourne is a hotspot, with one in 10 babies having a food allergy at 12 months – the highest incidence of food allergy reported in the world.
Food allergy sparks a strong reaction in the community – something Katie’s own condition has allowed her to observe. “It’s very complex and people have very strong views one way or the other. It doesn’t exist, or it does exist, or they’re hyper anxious.
“My view is that we should empower people to be able to eat what they need to eat, that’s safe for them. That doesn’t matter if it is coeliac disease, an intolerance, or an allergy.”
Katie’s two large cohort studies are behind most of the Institute’s food allergy findings. HealthNuts involves 5,300 children, diagnosed with food allergy at age one. It’s the largest single-centre population based study of food allergy in children ever mounted. The second is SchoolNuts, a population-based study of 10,000 school kids aged 10 to 14.
Research led by Katie has identified three hypotheses – which she summarises as the Five Ds – contributing to Australia’s high rates of allergy. These are dry skin and diet, dogs and dribble, and Vitamin D.
One of the biggest impacts of the research is its influence on Australian and American infant feeding guidelines, which were changed to advise parents that introducing egg earlier in their baby’s diet is not only safe, but may even prevent egg allergy.
‘Dogs and dribble’ relates to findings that exposure to more bacteria in the home – whether from older siblings, a dog or a dummy dropped on the floor and popped back in bub’s mouth – was not necessarily a bad thing for kids’ immune systems. In fact, a few extra germs might even have a protective effect.
Dry skin refers to an eczema gene, found to increase the risk of food allergy, and diet to delaying allergenic solids such as peanut.
Low Vitamin D levels are suspected to play a role too. Katie is now leading a trial, Vitality, involving 3,000 babies, to see whether food allergy can be prevented in the first year of life by supplementing infants with Vitamin D drops.
Allergy rates are lower in northern Australia, where there is more sunlight and therefore less Vitamin D deficiency in kids. Melbourne, with its lower levels of sunlight, is an allergy hotspot.
Unlike North America and Europe, where infants are supplemented with Vitamin D drops and the population consumes dairy products fortified with the vitamin, no such policies exist in Australia.
A more recent finding published this year suggests Asian children may be predisposed to food allergy but environmental factors in Asia are protective.
Children with the highest rates of food allergy across Victoria were found to be those who were Australian-born but whose parents were born in Asia. However children born in Asia who migrated to Australia in the first five years of life were completely protected.
All of these factors form a different piece of the puzzle put together by Katie and her team.
“We really feel like we are on the edge of something because we know food allergy has risen over the past 20 years. So if it’s happened that quickly, then we must be able to stop it,” Katie says. “There’s something we should be able to identify. It’s just so tangible.”