Australian researchers have discovered that food allergies in children are linked to a hyperactive immune system at birth.

Analysis of cord blood from more than 1,000 infants has shown that children who have a hyperactive immune system when they are born are more likely to develop food allergies in their first year of life.

As reported in the Science Translational Medicine Journal, an “immune signature” has been uncovered by Australian researchers in the cord blood of children with clinical signs of food allergies at 12 months old.

While at present it cannot be proven that the heightened immune response at birth caused food allergies, Professor Len Harrison of the Walter & Eliza hall Institute and one of the study’s authors, said it “clearly differentiated these children from the rest,”

“This study really emphasises how critical it is to look at pregnancy and early life to really understand why chronic immune and inflammatory disorders such as allergies develop in childhood and later,” Professor Harrison said.

Recent decades have seen a rise in childhood food allergies, with most of the increase seen in children under the age of five.

Professor Harrison said the discovery could have implications for the development of a screening test for children at risk, “but the most important thing is to figure out what causes this and to change those circumstances”.

“I think the likelihood of a [genetically inherited abnormality] being the sole cause of this phenomenon is low,” he said. “I think it is more likely to be acquired somehow.

“One of the reasons for that is that the incidence of food allergy has increased considerably in the last 20 or 30 years or so, and really that can only be due to environment.”

Researchers are also investigating whether other environmental factors, such as infection of the placenta or amniotic fluid, the influence of the mother or baby’s gut microbiome, or the nutritional status of the mother may play a role.

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