Whenever you give your child tomato sauce, they have a reaction. But when you give them tomatoes in other forms, nothing happens. Could it be an allergy?
“This is not an allergy,” says Dr Juan Trujillo, a paediatric allergist and co-director of the Centre of Excellence in Allergy at Cork University Hospital and UCC.
“For allergy, there’s always a reaction when you have the same culprit food.”
The hospital’s allergy centre is the only specialised allergy service outside of Dublin and the only centre in Ireland accredited by the World Allergy Organisation.
“It sees 3,000 patients a year between new, return, and follow-up. They’re aged from one day old to 16 years.”
Trujillo says the most common childhood food allergens here are milk, eggs, peanuts and tree nuts (hazel, Brazil, cashew, walnut).
“In other parts of the world, it changes. Australia has the highest macadamia nut allergy in the world because they eat a lot of macadamia.”
Dr Maeve Kelleher, a consultant in paediatric allergy at CHI, Crumlin, says traditionally less common allergens are emerging here.
“Wheat, fish, legumes — peas, beans — and seed allergy. Because we’re increasingly using them, eating different foods than 20 years ago. When I worked in London, we saw a lot of legume allergies in cultures that used lentils a lot.”
There are two types of food allergy, depending on symptoms and when they happen.
IgE-mediated food allergy is triggered by the immune system producing immunoglobulin E (IgE). Symptoms develop just seconds or minutes after eating. There’s a greater risk of anaphylaxis with this allergy type.
“Symptoms come on straight away, though sometimes can appear after one to two hours. They can include swelling of the face, skin reactions, or breathing troubles,” says Trujillo.
Non-IgE-mediated allergic reactions are caused by different immune system cells. This type can be hard to diagnose because symptom development is delayed.
“It could be two to 24 hours after ingesting the culprit food,” says Trujillo. Symptoms are often gastrointestinal: Abdominal pain, mucus, bloody diarrhoea and, in young children, colic.
Evidence-based tests exist for IgE-mediated food allergies, but not for the non-IgE type.
“Taking a good clinical history is essential — sitting with the parent, asking about the child’s reaction, the timing of it, what they think the cause is,” Trujillo says.
He warns against removing any suspect food from your child’s diet unless a doctor has advised this. Instead, keep a diary of their food intake, “record any symptoms in a calendar”, and bring it to the doctor.
“You have to become like Sherlock Holmes at home — start looking at things that are connecting.”
Trujillo believes we are in an “allergy epidemic” due to delayed introduction of foods to very young children.
“Ten to 15 years ago, the [advice] was to delay introduction of so-called allergenic foods — milk, eggs, tree nuts, peanuts, soya bean, fish — sometimes for one to one-and-a-half years.
“But delaying introducing these in those with an allergic propensity actually increases chances of their becoming allergic to the foods.”
When food is the culprit
With today’s focus on allergy prevention, he says parents are encouraged to introduce a diversity of foods into their children’s diets early — even before six months of age. Since following this changed advice, Trujillo says “the usual patient coming to our clinic now is allergic to one or two foods — instead of having five or six things they avoid”.
Treatment for food allergy depends on the culprit food, he says. “For milk and egg allergies, we use the ‘milk and egg ladder’ — progressively introducing different products containing milk and eggs in a stepped approach so as to increase amount of that food being eaten at home”.
However, he urges doing this only under supervision of a paediatric allergist or specialist.
In the case of other food allergies, they will mostly not be cured and avoidance is the recommended strategy.
Knowing how to treat moderate and severe reactions, such as anaphylaxis, is a must. “This is where adrenaline auto-injectors come in. We advise parents to always have them [available to their child] and to know how and when to use them.”
Kelleher confirms that — though not available in Ireland — oral immunotherapy treatments are now emerging. She points to the Vitesse trial in which Ireland is participating. It is evaluating an investigational drug patch for four- to seven-year-old children with peanut allergy. The small amount of peanut protein in the patch is designed to potentially desensitise a peanut-allergic person by repeated exposures via the skin.
“Before the patch, you might have reacted to one-tenth of a peanut. After the patch, you won’t react until you have two peanuts. This is the goal — it would be a lifelong treatment rather than a cure,” she says.
Do children outgrow food allergies?
“It depends on the food,” says Trujillo. “Eight or nine out of 10 will outgrow milk and egg allergies by age five, two out of 10 might grow out of peanut and tree nut allergies by age eight. For most children in Ireland right now with a peanut or tree nut allergy at age 10 or 12, they probably won’t outgrow it. But as we move towards new ways to treat these allergies, there could be more hope for younger children.”
Intolerance isn’t an allergy
Allergy disinformation is widespread.
“It can come from healthcare professionals doing so-called allergy and intolerance tests that aren’t accepted by the medical community. These won’t distinguish what true allergy is — they could give false information,” says Trujillo.
Some 50% of patients who attend the allergy centre have had “wrong or inadequate management by themselves or by other non-specialists”, and it has led to avoidance of foods.
He says it is very easy to eliminate a food from a child’s diet, but not so easy to return it.
“Eliminating foods can cause nutritional problems. Children learn to eat various foods in their early years.
“If you stop them eating [some foods] at this stage, they become picky eaters.”
Trujillo acknowledges the difficulty of finding paediatric allergist support in Ireland.
“When parents are looking for information, they can sometimes look for any kind of answer.”
The first line of support should always be the GP. “In Cork, we meet GPs and community dietitians every two months to help build knowledge of true allergy because they are the filters.”
Terms like “food intolerance” and “food insensitivity” can also create confusion.
“Intolerance isn’t an allergy — it’s a food unsuitable to your body. It’s almost always dose-dependent. Maybe when you drink a lot of milk, rather than a little, you get symptoms like flatulence, diarrhoea, or bloating,” explains Trujillo. Food allergy, on the other hand, is not dose-dependent. “Sometimes it may be a mild reaction, sometimes severe, but the particular food always gives a reaction.”
Similarly, food insensitivity is not allergy either. “It’s another way to say some foods will interrupt your system.”
The CHI paediatric clinic sees a couple of thousand allergy patients annually. “We’ve done a lot of work to reduce it,” says Kelleher, adding that long wait times can “push people” to look for information wherever they feel they can get it.
“There are definitely a lot of myths about food allergy. Our advanced nurse practitioner, Mairéad Sheehan, did a study looking at people on long waiting lists and the effect of giving them myth-busting allergy information. The study showed this improved quality of life. Now, we give the information to all patients.”
Common myths range from “allergic reactions get worse each time”, to “adrenaline pens are dangerous”.
Kelleher also comes across the misplaced belief that children with eczema should be allergy tested to determine the cause of their eczema. “But eczema is a skin barrier condition.”
The real link between eczema and food allergy is that babies with eczema are more at risk of immediate-type food allergies. “For us, eczema is a flag to ensure the common food allergens are introduced to these children to try and prevent allergy.”
Kelleher and her team embrace the reality that online sources are where many people get their information today.
“We want to get reliable, evidence-based information out on social media. It can be challenging to do this in a busy hospital.”
As Trujillo puts it: “We will fight the allergy epidemic with knowledge.”
