Earlier this month US-based allergist, immunologist and paediatrician Dr Mitchell R Lester gave a lecture on asthma and allergies at Portiuncula Hospital in Ballinasloe, Co Galway. He spoke to Hélène Hofmanabout identifying food allergies and managing them
As many as 5-8 per cent of children under two years of age have an allergy or food sensitivity, according to allergist, immunologist and paediatrician Dr Mitchell R Lester.
However, according to Lester, who is based in Connecticut in the US, identifying an allergy (hypersensitivity or exaggerated response to a substance) in a young child can be difficult.
"Certainly with children we need to be aware of any allergies they might have," says Lester.
"These can be triggered by a number of things, such as dust, mould, cats, dogs, pollens in the air, and many have food allergies."
Although children are unlikely to develop seasonal allergies before the age of three, food allergies can be common.
"A toddler with atopic dermatitis, which is a type of eczema, may have a food allergy. So if they have moderate to severe eczema, that may be contributing," he says.
"If they are allergic to eggs, for example, and the mother is nursing and eating eggs, that might be affecting the child.
"With food allergies, the most effective cure at the moment is elimination. So if they're reacting badly to something, the mother should identify what it is and eliminate that from her diet," he says.
According to Lester, eggs, cow's milk, wheat and soy account for 90 per cent of food allergies in young children.
However, in later life, peanuts, tree nuts, gluten, shellfish and fish are the most common triggers, making up 90 per cent of allergies in older children and adults.
"It's not clear why it's these particular foods, but they are generally foods which are not eaten early in life. One theory is the level of protein they contain," says Lester.
"Interestingly, there is a higher instance of peanut allergies, for example, in the US than in Asia and we think that might be because they eat them younger there or it could be to do with the way they are prepared - in Asia they are fried and boiled, while here in the US they are more likely to be dry roasted."
According to the Asthma and Allergy Foundation of America, the majority of people with a food allergy have a peanut allergy, and it estimates that about one in every 100 children and adults is affected.
Irish experts think that as many as 16,000 children in Ireland could have a peanut allergy and an increasing number of children are developing the intolerance.
Although EU regulations, introduced in November 2005, compel food manufacturers to label products that contain any of 12 major allergens, including peanuts and tree nuts, Lester says this labelling can be unclear.
"A label may say the product contains nuts, although nuts are not listed in the ingredients and this can cause a lot of confusion and anxiety.
"What happens is a company prepares a product with nuts near, or in the same factory as, a product that doesn't contain nuts and then puts it on the label.
"I would recommend checking with the manufacturers and then making a decision. They might tell you they're made on the same machine, or they might tell you they're made in the same factory but three floors away and so you might decide to keep eating that product," he says.
"With an older person it's quite obvious if they have an allergy. If you eat enough of something to trigger a reaction, it happens fast.
"If someone says they're itchy all the time then it's unlikely to be a food allergy. But if they eat something and it causes hives or breathing problems, for example, then you know it's a food allergy.
"With younger kids look out for the eczema," says Lester.
He warns that in the US several hundred people die from food allergies every year. In the EU that figure is estimated to be at least 150 deaths a year.
Incidences of food allergies have gone up in general. That may be due to more awareness and better diagnosis, which is important, because at the moment elimination is the most effective cure, he says.