Sunshine, Dirt, and a Little Bit of Peanut Butter

Isabelle Amy

Melbourne children are the most allergic in the world but further study is needed to make recommendations into young diets, a leading researcher says.

“Our recent study of twelve month old infants in Melbourne found that one in ten infants had a food allergy,” says Dr Jennifer Koplin, research fellow at the Murdoch Children’s Research Institute (MCRI).

It is this figure that has led Melbourne to be crowned ‘Allergy Capital of the World’, with the highest prevalence of food allergy ever recorded.

Such critical revelations have had many parents and scientists asking why it is that the world’s ‘Most Liveable City’ might also have the most sensitive kids.

Research in Europe has found that exposure to certain microbes such as those found in farm dust may be a legitimate protectant for children, and it seems that in the inner suburbs of Melbourne children are not interacting with those microbes nearly enough through things like hay, dirt and farm animals.

Peanuts are one of the most common allergies among children. Photo: US Department of Agriculture.
Peanuts are one of the most common allergies among children. Photo: US Department of Agriculture.

A study by Hamida Hammad of Ghent University in Belgium has found mice that are exposed to a low dose of endotoxin or farm dust were much less likely to develop asthma and allergies.

Similarly, in Melbourne, a team of researchers at the MCRI found that children who grew up in homes with dogs and older siblings were less likely to develop allergies.

As Dr Koplin explains, “both of those things change the sorts of microbes that infants are exposed to and coming into contact with a range of microbes early in life might be important for developing a healthy immune system”.

Georgette Green, a primary school teacher who has taught in the Northern Territory, the ACT and in Victoria, says Melbourne is certainly a region with comparatively high allergy rates.

“At the schools I taught at in the Northern Territory, I don’t recall a single student reporting an allergy. Melbourne definitely stands out in that regard,” she said.

Ms Green adds that “some children can experience real social isolation when they suffer from severe allergies and it can definitely be both a social and academic setback.”

Although the research looks promising, Dr Koplin stresses that she and her colleagues aren’t able to translate these finding into clinical recommendations just yet.

“What we don’t know at the moment is which microbes are involved or when an infant would need to be exposed,” she said.

Additional research by MCRI has found that dirt microbes and germs are not the only ingredients in building a healthy immune system in children and infants.

Vitamin D is also crucial. In recent trials, the MCRI team found infants who are vitamin D deficient are 3 times more likely to have an egg allergy and 11 times more likely to have a peanut allergy.

The likelihood of having multiple food allergies also rises in children with Vitamin D deficiency.

The partial attribution of Vitamin D deficiency to Melbourne’s allergy epidemic is particularly contentious, as Australia is one of the few western countries that does not fortify the food chain supply with Vitamin D.

But it’s believed that a significant lack of exposure to sunlight, rather than a dietary issue, is the most prevalent cause of vitamin D deficiency, which correlates with further MCRI research that found that the likelihood of allergy rose in populations living further from the equator.

This finding might suggest that Melbournian children are not getting the exposure to sunlight they require in order to build immunity and develop healthy stores of Vitamin D.

The researchers from Dr Koplin’s team are set to commence a study that will aim to determine whether vitamin D supplements in the first year of an infant’s life may help decrease the likelihood of developing a range of allergies.

Perhaps the most crucial finding however has been that the early introduction of “allergenic foods” such as milk, eggs and peanuts into an infant’s diet may help prevent a child from developing allergies to those foods.

Many parents tend to avoid allergenic foods because of a belief that it could be dangerous or problematic, but as Dr Koplin asserted, “there is good evidence that delaying the introduction of peanuts can increase the risk of developing peanut allergy in some children”.

In the future her team hopes to make firm clinical recommendations about a child’s diet that will prevent children from developing possibly life-threatening allergies altogether.