The rising rate at which Australian children are being admitted to hospital for serious food allergies has flattened since infant feeding guidelines were changed, new research shows.
The rate of hospitalisation for food anaphylaxis has increased in Australia in recent decades – but data suggests that changes to allergy prevention and infant feeding guidelines in 2008 and 2016 have helped to stem the rise in young children and teenagers.
In 2008, the Australasian Society of Clinical Immunology and Allergy guidelines were changed to recommend that allergenic solid foods should no longer be delayed, and in 2016 they were again updated to suggest such foods should be introduced in the first year of life.
Study co-author Prof Mimi Tang, an immunologist at the Murdoch Children’s Research Institute, said the greatest benefit of the updated guidelines was in children aged one to four.
In this age group, the researchers found that the yearly rate of increase in anaphylaxis admissions dropped from 17.6% between 1999 and 2007 to 6.2% between 2008 and 2015, and to 3.9% after 2016.
In the first two periods, the annual rate of increase in children aged five to nine dropped from 22% to 13.9%, and after 2016 the rate of increase was -2.4%.
For 10- to 14-year-olds, the annual rate of increase dropped from 18.0% between 2008 and 2015 to 10.8% after 2016.
Tang said there had been important changes to allergy prevention advice in the last 15 years. “Prior to 2008, all of the food allergy … prevention guidelines around the world were advising to delay the introduction of allergenic foods such as egg, milk and peanut until the ages of somewhere between two and four, depending on the food,” she said.
“The reason these recommendations were in place was based on theoretical concerns that the gut barrier was perhaps not as strong in young babies.”
But a growing body of evidence showed that delaying allergenic foods was associated with an increased risk of developing food allergies.
In 2015, a randomised controlled trial published in the New England Journal of Medicine found that introducing peanuts into the diet between the age of four and 11 months drastically reduced the chances of developing a peanut allergy by age five.
That research “provided for the first time the highest-level evidence that earlier introduction could prevent food allergy”, Tang said. “Subsequent to that there were other studies showing similar findings for egg and milk allergies.”
In the new study, published in the Journal of Allergy and Clinical Immunology, Tang and her colleagues noted an ongoing increase in anaphylaxis hospitalisation rates in teenagers aged 15 and older at the time the research was completed. People in this age group were born before the 2008 changes to the Australian guidelines.
“We actually only saw flattening of rates in the children that could have benefited from the timing of these updates,” Tang said.
There was, however, an acceleration in the year-on-year rate of increase for children aged one year and younger.
“Children with food allergy typically react when they have eaten the food for the first time,” Tang said. The finding in infants suggests “that first exposure is happening in the first year of life rather than beyond”, she said.
“But if you look at zero- to four-year-olds, in that cohort overall the rates are flattening. So whatever flattening is occurring with the one- to four-year-olds, it’s greater than the increase in the under ones,” she said.
Overall, annual food anaphylaxis admission rates in children and teenagers increased ninefold in Australia between 1999 and 2019.
“There are many things in the environment that may be contributing to the rise in food allergies,” Tang said. Such factors potentially include changing diet and exposure to a narrower range of microbes.