A team from a leading children's hospital carried out what they claim is the largest study to date on children who have milk and egg allergies.
They found a trend towards more severe and persistent allergies in children, although there was evidence that some lose allergies during adolescence.
The researchers say food allergies are more 'unpredictable' and 'aggressive' than before.
In America, 3 per cent of children are allergic to milk and 2 per cent allergic to eggs.
A team from Johns Hopkins Children's Center in Maryland followed 800 children with milk allergy and just under 900 with egg allergy over 13 years.
While earlier research found that three-quarters of children with milk allergy grew out of it by the age of three, the team said that only 20 per cent of children taking part in the study were no longer allergic to milk by the age of four and 42 per cent by the age of eight.
The trend was also seen in the egg allergy group, with just 4 per cent growing out of this allergy by the age of four and 37 per cent by age of ten.
Lead researcher and head of Allergy and Immunology Robert Wood said, 'The bad news is 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 them, and those who do, do so later than before.
'We may be dealing with a different kind of disease process than 20 years ago. Why this is happening, we just don't know.'
FURTHER INFORMATION
The studies are in the November and December issues of the Journal of Allergy and Clinical Immunology.
