How can your new baby be ‘primed’ to have a reaction to soy, nuts or dairy before it is even old enough to walk or talk?
“When babies have an allergic reaction to food, it’s frightening,” says Associate Professor Vuillermin, a paediatrician from Barwon Health, Deakin University and the Murdoch Children’s Research Institute.
“And if it is a severe reaction, it is even more frightening.”
Unfortunately, says A/Prof Vuillermin, food allergies in babies are common in Australia.
“There has been a three-fold increase in hospital presentations due to food allergy over recent decades, and most of this increase has been among children under five years of age.
“In fact, up to 1 in every 10 babies in Melbourne will develop a food allergy during the first year of life.”
A/Prof Vuillermin stresses that although the food allergies issue is huge, the problem facing Australia is not ‘just’ about food allergies.
The bigger issue is about recent increases in immune-related diseases – from diabetes to Multiple Sclerosis, to chronic inflammatory conditions like cardio vascular disease, which have increased in prevalence all around the world over the last 50 years or so.
“Much of that increase is unexplained,” he says. “And food allergies – an immune-related condition – are the most recent cab off the rank in terms of the increase.”
They found a new immune ‘signature’, which can now be used to identify babies at risk of developing food allergies in the first year of life.
The matter, he says, warranted investigation. The concerned paediatrician was recently involved in the first ever study in humans that associated the existence of a ‘primed immune system’ causing food allergies with babies.
A/Prof Vuillermin recently joined fellow researchers Dr Yuxia Zhang and Professor Len Harrison from the Walter and Eliza Hall Institute to investigate how a baby aged one and under, can develop food allergies.
The team focused on a recruited cohort of pregnant mothers and babies from the Barwon region of Victoria. When the babies reached age one, they performed comprehensive allergy testing.
What the team found was that from 174 babies tested, 61 had food allergies. “The overall prevalence of food allergies in this group was just under eight per cent of children at one year of age.”
The findings, published yesterday in the journal Science Translational Medicine, show that some babies have immune systems that are ‘primed’ for food allergies by the time they are born.
A/Prof Vuillermin says the findings were more or less consistent with other studies around Australia, although they came in at a lower rate than the Melbourne average.
“But there’s no reason to suspect that the rates are dramatically different in different parts of Australia.”
What does ‘a primed immune system’ mean?
The researchers analysed each baby’s cord blood and linked the results back to the child participants who had developed food allergies by age one.
This is where the team discovered scientific gold. They found a new immune ‘signature’, which can now be used to identify babies at risk of developing food allergies in the first year of life.
“What we found in the babies who developed food allergies is that when you stimulate their T cells, they produce more inflammation,” he explains.
These young ‘hyper responsive’ immune cells then push the second line of immune cells, ‘predisposed’ to react to some foods, down an allergic pathway. An immune response results. And that’s what gives a baby a reaction to soy, dairy and nuts in the early years of their life.
A newly discovered pathway to prevention
So what now that the researchers have discovered the mechanistic part of the food allergy process in babies? A/Prof Vuillermin says the next step for researchers is to move on from how to determine why.
“Maybe it’s genetic? The increase in food allergies are far too high to be due to genetic reasons alone.”
“Environment might be at play. But it could also have something to do with the composition of the mother’s gut flora during pregnancy, vitamin D or their diet.”
Researchers are also yet to discover the hyper immune cells, called monocytes, were activated during pregnancy or birth.
“Ultimately, what we’d like to do now is identify avoidable risk factors that are modifiable. Or identify specific interventions that we can introduce to prevent food allergies in babies.
“And that’s a pretty important challenge.”