Childhood allergies - conflicting views

Two studies recently completed at the Johns Hopkins Children's Center suggest that that the prognosis for a child with a milk or egg allergy appears to be worse than it was 20 years ago. ‘Not only do more kids have allergies, but fewer of them outgrow their allergies, and those who do, do so later than before,’ said lead researcher Robert Wood.

Previously, studies have reported that 75% of children with milk allergy outgrew their condition by the age of three, but the new study indicated that only 20% of children may outgrow their allergy by four years of age. By eight years of age, 42% of the children had outgrown the condition, while 79% were allergy-free by the age of 16.

Similar trends were seen in the egg-allergy group, report the researchers, with only 4% of the children
studied outgrowing this allergy by four years of age. Only 37% were allergy-free by the time they reached ten years of age, which rose to 68% by the age of 16.

Wood and co-workers reported a correlation between a child's blood levels of milk and egg antibodies (IgE) – the immune chemicals produced in response to allergens – and disease behaviour: the higher the level of antibodies, the longer the time to outgrow the allergy.

‘Our data suggests that this does not happen as early as previously thought. Furthermore, we have identified an egg IgE level of at least 50 kU/L as a marker of persistent egg allergy,’ wrote the authors.
In terms of milk, they added: ‘Our findings stand in marked contrast to the study that is most often quoted, which found that 75% of children with IgE- mediated milk allergy were tolerant by the age of three years. However, one positive finding is that patients did continue to achieve tolerance well into adolescence.’

A major new study led by Professor Tara Dean at the University of Portsmouth followed nearly all the babies born in one year on the Isle of Wight over a period of three years. Their conclusions were that not only were parents too quick to assume their child had an allergy or intolerance for a specific food, but also that food hypersensitivity has not increased since the only other major study on the subject 20 years ago.

Dr Venter said that by the age of three about three-quarters of the babies who were allergic to, or intolerant of, milk had outgrown their reaction and half had outgrown their reaction to eggs. Babies who reacted badly needn’t necessarily avoid these foods forever. They could very easily be eating cakes made using eggs or milk by the age of two and scrambled eggs by the age of three, although a small proportion may remain allergic throughout life.

Of the 807 babies in the study, more than a third of their parents, 272, said their child was allergic or intolerant to one or more foods. The babies were studied at six months, one, two and three years of age and the actual number who proved to be allergic to any food by the age of three was less than 60.
Of those who proved to be allergic to a food at the age of three, the most common allergies were to peanuts, eggs and milk.

The main reason parents gave for thinking their child was allergic to a food was their child coming out in a rash, itching or developing eczema; a gastrointestinal problem (tummy ache, vomiting, diarrhoea, constipation or colic) or a respiratory problem (shortness of breath, asthma, wheeziness, a runny nose and coughing).
The most likely foods to cause an allergic reaction in the children confirmed as allergic at age three were: peanut (11); eggs (nine); milk (four); wheat, brazil nut and almond (two); gluten, hazelnut, cashew nut and corn (one); fish and tomato (0).

Journal of Allergy and Clinical Immunology November 2007, Volume 120, Issue 5, Pages 1172–1177
Journal of Allergy and Clinical Immunology December 2007, Volume 120, Issue 6, Pages 1413–1417

First Published in March 2008

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