One in 20 children show food hypersensitivity by two years of age – but only half of children with confirmed food hypersensitivity showed IgE, the antibody responsible for allergic diseases.
Researchers in Hampshire followed 823 infants until two years of age. Food hypersensitivity was diagnosed using a double-blind, placebocontrolled food challenge. Symptoms that emerged up to 48 hours after the end of the food challenge were regarded as indicating hypersensitivity.
A quarter (25.5 per cent) of parents believed that their child showed food hypersensitivity but the cumulative incidence of confirmed food hypersensitivity by two years of age was only 5.0 per cent. Eczema and gastrointestinal symptoms were the commonest presentations (39.0 and 26.8 per cent respectively). No child had a history of anaphylaxis.
Overall, by two years of age, 2.6 per cent of infants had developed IgE-mediated food allergy, including to hen’s eggs (2.1 per cent), cow’s milk (0.7 per cent), peanuts (0.6 per cent), and soy, wheat and fish (each 0.1 per cent). Eight of the 21 infants with IgE-mediated food allergy reacted to more than one food.
A similar proportion – 2.4 per cent – had food reactions that were not mediated by IgE, including to cow’s milk (1.7 per cent), hen’s eggs (0.6 per cent), soy (0.2 per cent), and peanut, wheat, lentil and broccoli (each 0.1 per cent). Four of the 20 infants reacted to more than one food. No infant showed IgE-mediated and non-IgEmediated food reactions.
Several factors independently predicted food hypersensitivity. For example, wheeze at the initial assessment increased the risk almost 21-fold (adjusted odds ratio [OR] 20.6) and maternal atopy about 88-fold (OR 87.5). Eczema (OR 18.7) or rhinitis at the initial assessment (OR 4.8) and infants’ healthy dietary patterns (OR 0.3) independently predicted IgEmediated allergy.
Predictors for non-IgEmediated food hypersensitivity included maternal consumption of probiotics during breastfeeding (OR 45.4), dogs in the home (OR 19.5), age at first solid food introduction (OR 0.60) and healthy dietary patterns (OR 0.28).
“IgE mediated and non-IgE mediated [food reactions] should be considered as two separate conditions and treated accordingly,” said Kate Grimshaw, senior research fellow at the University of Southampton and specialist paediatric dietitian at Southampton Children’s Hospital.
“We have shown that they have distinct differences in reactions and the risk factors associated with them. It is important that healthcare professionals recognise that a child may be reacting to a food, despite test results being negative.”
(Clin Transl Allergy DOI:10.1186/s13601-016-0089-8)