AsianScientist (Feb. 24, 2016) – Australian-born children with Asian mothers have higher rates of nut allergy than Asian-born children who migrate to Australia, researchers from the University of Melbourne have found.
This is the first large, population-based study to show the prevalence of peanut and tree nut allergy, two of the most common foods that cause allergic reactions, and builds on more than a decade of allergy research. The paper was published in Clinical and Experimental Allergy.
The findings are helping to shed light on Australia’s allergy epidemic as scientists piece together clues to determine why food allergy rates continue to rise. Previous research has shown unexpectedly high rates of nut allergy in Melbourne, with three percent of one-year-old infants demonstrating a peanut allergy during medically-supervised food challenges. This has led to Melbourne being dubbed the ‘food allergy capital’ of the world.
The study, involving more than 57,000 five-year olds, also revealed that children from urban areas are more likely to have nut allergies than children from rural regions, and that nut allergies are more common amongst children of mothers with higher education and socio-economic status.
Researchers from Murdoch Childrens Research Institute and University of Melbourne analyzed the results of the 2010 School Entrant Health Questionnaire, a report filled out by a parent or guardian about their child’s health and wellbeing at the beginning of primary school in Victoria.
Researchers assessed the overall prevalence of parent-reported nut allergy (tree nuts and peanut), and whether this was affected by region of residence, socio-economic status, country of birth or history of migration.
Of the 57,000 respondents, almost 2,900 parents reported a food allergy (five percent) and slightly over 1,700 (3.1 percent) reported a nut allergy. While Australian-born children of Asian descent were more likely to have a nut allergy than non-Asian children, children born in Asia who migrated to Australia had lesser risk.
Murdoch Childrens Research Institute Professor Katie Allen, one of the researchers in the study, noted that migration from Asia after the early infant period appears to be a protective factor against the development of nut allergy. For Australian-born Asian children, their exposure to a different diet, bacterial and UV environment could be environmental risk factors.
“We know there are rising rates of migration from East Asia to Australia. Our finding that migration from Asia to Australia after birth can protect against early onset allergic disease such as food allergy provides a potent clue for us to follow when trying to understand why food allergy is on the rise,” said Allen.
The results, she said, suggest that removing children from the Asian environment or conversely exposing them to environmental risk factors in our Western environment uncovers a genetically-determined risk of food allergy in children of Asian descent.
Allen echoed this sentiment for children raised in rural areas.
“The overall presence of nut allergy in metropolitan Melbourne was 3.4 percent, compared with 2.38 percent in non-metropolitan areas,” said Allen.
“While the question still remains as to why allergy rates are on the rise, the urban-rural difference could be down to the hygiene hypothesis—which raises the possibility that our urban environment with less diverse microbial exposure may contribute to the rise in allergies.”
“It strongly suggests that early life environmental factors linked to the modern lifestyle play a key role in allergy development. Understanding these factors better will provide opportunities to intervene to prevent food allergy in the future.”
The study also revealed that nut allergy was more commonly reported amongst children of mothers with higher education levels, and a high socio-economic index. The research team suggests that mothers with higher levels of education and income from urban areas are more likely to seek medical advice for a food reaction, and therefore more likely to report a nut allergy in their child.
The article can be found at: Panjari et al. (2016) Nut Allergy Prevalence and Differences between Asian Born Children and Australian Born Children of Asian Descent: A State-wide Survey of Children at Primary School Entry in Victoria, Australia..
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Source: University of Melbourne; Photo: Shutterstock.
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