Nearly two-thirds of children with food allergy have outgrown their allergy by four years of age, however, there continue to be remarkably high rates of any allergic disease, with almost half of the children surveyed experiencing some form of allergy by four.

The new findings released during Food Allergy Week from MCRI's HealthNuts study involving 5276 kids, recruited at age one, have shown the prevalence of challenge-confirmed food allergy reduced from 11 per cent at age one to 3.8 per cent at age four.

Resolution of egg allergy was the main driver of this change, dropping from 9.5 per cent to 1.2 per cent.

The prevalence of peanut allergy also fell from 3.1 per cent to 1.9 per cent. Despite this, peanut allergy was still the most prevalent food allergy in four-year-old children.

Previously, the HealthNuts study reported on the prevalence of food allergy when 2800 participants had been recruited. The interim results showed more than 10 per cent had challenge-confirmed food allergy at age one.  This is higher than reports in other countries, ranging from one to five per cent, and earned Australia the unfortunate title of 'food allergy capital of the world'.

The new results, published in the Journal of Allergy and Clinical Immunology, reflect previous research which has shown about 20 per cent of children will outgrow peanut allergy and 80 per cent will develop tolerance to egg.

The prevalence of asthma, eczema and hayfever in four-year-olds was also measured, said the study's lead author Dr Rachel Peters from MCRI.

Asthma prevalence was 10.8 per cent, eczema was 16 per cent and hayfever 8.3 per cent, Dr Peters said.

"Overall, 40 to 50 per cent of this population-based cohort experienced symptoms of any allergic disease in the first four years of their life," she said.

"Although the prevalence of food allergy decreased between ages one and four, the prevalence of any allergic disease among four-year-old children is still remarkably high."

Senior author Prof Katie Allen said the study results were among the most robust in the world as they were derived from a large sample size, a high response rate from participants and relied on the gold-standard oral food challenges to measure allergies. Other non-food allergies were measured by questioning parents about whether their children had been diagnosed by a doctor and experienced symptoms of asthma, eczema or hayfever in the past year.

Prof Allen said there had been an increase in the prevalence of allergic diseases internationally, initially marked by a rise in asthma, eczema and hayfever, peaking in the 1990s and 2000s. "This was followed by the second wave of the allergy epidemic with an increase in reported food allergies over the last two decades. Allergies are now recognised as a significant public health concern," Prof Allen said.

Children in the HealthNuts study will now be followed up at age six and 10. 

Food Allergy Week is an annual initiative from Allergy & Anaphylaxis Australia that aims to increase awareness of food allergy in an effort to promote understanding and help protect those at risk. 

Health Nuts Study Participant - Samuel's story

Samuel Hill (image above) was one of the last participants to join the Health Nuts Study. He had suffered from terrible eczema since birth, which was potentially linked to food allergy. He went from a child who was spending probably 70% of his life in miserable agony to a happy, bright and bouncy boy.

At the 4-year-old tests, they discovered that Samuel was no longer intolerant to egg. His parents were thrilled and cooked him his first boiled egg in three years. Around the same time, the family received the devastating diagnosis that Samuel had Type B cell Non-Hodgkin's Lymphoma. This diagnosis meant he had to pull out of the study.  Following successful treatment, Samuel was able to rejoin the study however as a result of his treatment, his immune system was severely depleted which meant that the team had to start the testing from scratch.

The results showed that luckily Samuel hadn't developed any new allergies, but they were able to identify more specifically which foods Samuel was allergic to, including nuts, sesame, peanuts and cashews.

Samuel's dad, Craig was very grateful that his son was able to take part in the study. "We cannot begin to tell you the difference this study has made to both our lives and Samuel's. We discovered he was allergic to nuts. At the time we had no idea what the symptoms were and we were just stunned at what we missed. Not to mention the fact that they informed us that he was potentially anaphylactic where nuts were concerned. As a parent there is not anything I can think of that is more humbling than discovering that peanut butter toast could be the last thing your child ever eats!!"