Melbourne researchers have found solid evidence that something in Australia’s environment could be triggering child nut allergies.

The Murdoch Children’s Research Institute compared more than 57,000 Victorian school health questionnaires hunting for clues for the reason Melbourne has been dubbed the food allergy capital of the world.

Of the questionnaires reviewed, 5 per cent of parents reported their child had a food allergy and 3 per cent reported a nut allergy.

“The first thing we noted [in previous studies] was Australia has such high rates of food allergies … and the second thing we then noticed was that Asian [background] children have really high rates,” Professor Katie Allen said.  This [latest] piece of information shows that if children were born in Asia and then moved to Australia they are protected against food allergy.

“This is an incredibly exciting finding because it provides really solid evidence about the fact that there’s something in the environment that’s driving this allergic epidemic.”

Professor Allen said the research shows that children born in Australia but of Asian descent were three times more likely to develop a nut allergy than non-Asian infants.  This discovery suggests a heightened genetically-determined risk of food allergy.

“However, if the children were born in Asia but then moved to Australia they seem to be completely protected from the nut allergy, so zero percent,” she said.  “The risk factors we think that are probably important include something called the ‘Hygiene Hypothesis': the way infants are fed food in the first few years of life, and the UV exposure or ‘Vitamin D Hypothesis’.

“So it’s probably to do with modern lifestyle; so bugs, food and sunshine.”

Professor Allen said ironically the anti-skin cancer message of “slip, slop, slap, wrap” had led to low rates of vitamin D across the community.

“Some countries in the northern hemisphere actually supplement infants with vitamin D … Australia is one of the few countries in the world that neither fortifies its food chain supply by adding vitamin D to milk and dairy products, nor has supplementation of infants in the first year of life,” she said.

Professor Allen told the ABC, that researchers are currently conducting a three-year trial of vitamin D supplements for infants to investigate whether it would have any impacts on allergy rates.

She added that there were also “clear differences” in microbes found in Australia and Asia, which could give those born in Asia some protective effect against allergies.

The “hygiene hypothesis” was also possibly behind the disparity in the number of metropolitan Victorian children with nut allergies [3.4 per cent] and those reporting allergies in non-metropolitan areas [2.4 per cent], researchers found.

“Our urban environment with less diverse microbial exposure may contribute to the rise in allergies,” Professor Allen said.

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