Children born in Asia who migrated to Australia have a decreased risk of developing a nut allergy, say researchers.

Being born in Asia protects Australian schoolchildren from nut allergies, suggests a new study.

The researchers found that Australian-born children with Asian mothers had higher rates of the allergy than Asian-born children who migrated to Australia.

Western environmental risk factors such as diet changes, microbial and UV exposure may be part of the reason, they suggest.

The study of more than 57,000 five-year-olds also revealed that children from urban areas are more likely to have nut allergy than children from rural regions, and it's more common among children of mothers with higher education and socio-economic status.

The Murdoch Childrens Research Institute and University of Melbourne researchers said their study helped shed light on Australia's allergy epidemic.

They analysed the results of the 2010 School Entrant Health Questionnaire, a report filled out by a parent about their child's health and wellbeing at the beginning of primary school in Victoria.

Five per cent of the parents reported a food allergy and 3.1 per cent reported a nut allergy.

Australian-born children of Asian descent were more likely to have nut allergy than non-Asian children, while children born in Asia who migrated to Australia were at decreased risk.

Institute researcher Professor Katie Allen said that migration from Asia after the early infant period appeared to be a protective factor against the development of nut allergy.