Approximately one in 20 Australian adolescents aged between 10 and 14 years have a food allergy. This number suggests that the previously reported rise in food-induced anaphylaxis in adolescence may actually reflect an increasing commonness of food allergy, rather than a growth in the reporting of anaphylaxis.

This is one of the few population-based studies in the world examining the frequency of food allergy in early adolescence using the gold standard of oral food challenge (OFC).

The results of the study confirmed that the prevalence of food allergy is around 5% in early adolescence. Peanut and tree nut are the most common allergies with each affecting 2-3% of adolescents.

Murdoch Children’s Research Institute’s (MCRI) Dr. Mari Sasaki, the study’s lead author said this further confirms that Australia has a worryingly high prevalence of food allergy.

“Although the rate of food allergy is not as high as in infancy, it is still concerningly high in early adolescence. Parents need to remain vigilant and look out for the signs that their child may have a food allergy,” Dr. Sasaki said.

The ‘SchoolNuts Study’ was undertaken by the Australian Centre of Food and Allergy Research, based at the Murdoch Children’s Research Institute (MCRI).

10,000 kids aged 10 to 14 took part in the study, which saw students and their parents complete a questionnaire regarding the adolescent’s food allergy or food-related reactions and other allergic diseases.

Clinic evaluation consisted of skin prick tests (SPT) and OFC where eligible. The SPT covered 15 food allergens – egg white, cow’s milk, soy, peanut, cashew, almond, hazelnut, walnut, pistachio, macadamia, pecan, brazil nut, pine nut, sesame and shellfish.

An OFC was undertaken if students were suspected to have a current food allergy from the response to the questionnaire and further information collected by phone with the SPT results

The results show that the prevalence of food allergy was approximately 5% in early adolescents.

“Peanut was the most common food trigger at 2.7% followed closely by tree nuts at 2.3%,” said the study’s senior author and leader of the Schoolnuts study, Professor Katie Allen.

Cashew had the highest prevalence of the tree nuts and egg had the highest reaction among the other (non-nut) foods.

SchoolNuts Study Participant
Fourteen year old Liam Wray participated in the SchoolNuts study in 2014. Liam and his family felt that participating in the study gave him a better understanding about his allergies.

Liam is allergic to cashews and peanuts and needs to carry an epipen as well as ventolin because he is a mild asthmatic. He was thought to also be allergic to almonds and hazelnuts but he was surprised and happy to discover that he can now eat these nuts without any allergic reaction.

Liam’s mum Lisa said it was easier to control his allergies when he was at preschool age. “We were always with him and we knew what he was eating. When he started primary school in 2008 we were very nervous and worried that he would have a severe reaction but the school was very supportive. First aid training was provided to teachers and a no nut policy was introduced because there were other children with severe allergies at the school.”

“We have always encouraged Liam if he was unsure about the food to ask whether there is nuts in it and if it did to avoid the food but not too make a big deal about it. We are very fortunate that Liam can tolerate almonds, hazelnuts, and that he understands what to do if he has an allergic reaction,” Lisa said.

The new results, published in the Journal of Allergy and Clinical Immunology, are in line with MCRI’s age one to four year old ‘HealthNuts’ study that showed that one in 10 children aged one suffer from a food allergy.

Senior author Professor Katie Allen said that previous data on hospital anaphylaxis admission rates showed that anaphylaxis related to food allergy was most common among preschool-aged children.

“Recent Australian data suggests that the increase in food anaphylaxis admission rates for older children is accelerating at a greater rate than for preschool-aged children. However, despite the accelerating increase in rates of anaphylaxis, the prevalence of food allergy in this age group has not been studied to the same extent as it has in early childhood,” Prof Allen said.

The strengths of this study are the number of participants and the thorough clinic evaluation which included OFC to confirm the diagnosis of a food allergy. In addition, the team have been able to investigate the prevalence of tree nut allergy, which has not previously been extensively researched.