Adherence to the current guidelines for detection of allergy to cow’s milk leads to overdiagnosis, i.e. misdiagnosing healthy children. Many mothers in this situation opt not to breastfeed, limit their diet or buy specialised formula. Such behaviour is supported by official recommendations, but many of their authors are associated with formula manufacturers. These conclusions were reached by scientists from Sechenov University and Imperial College London; the results were published in the journal JAMA Pediatrics.

As the authors of the article found out, about 14% of families believe that their child has an allergy to milk, while in fact only 1% of children suffer from it. Scientists believe that one of the possible reasons for this situation may be clinical guidelines for detecting allergies to cow’s milk proteins. To test this hypothesis, researchers analysed nine guidelines for diagnosing cow’s milk allergy published between 2012 and 2019 by medical organisations in several countries, mostly European.

Scientists have found that many guidelines consider excessive crying, regurgitating milk and loose stools as allergy symptoms, although they are often found in healthy children. Seven of the nine guidelines recommend that women who breastfeed exclude all dairy products from their diet if their child is suspected of having an allergy. However, a review of studies shows that the amount of cow’s milk protein that gets into the mother’s breast milk is not enough for a reaction in most children with allergies.

‘Many infants who are labelled as having milk allergy don’t have the condition. Having a child with suspected milk allergy can be a stressful time for any family. Misdiagnosing milk allergy could lead to another condition with similar symptoms being missed, or breast-feeding mothers needlessly following restricted diets – or even stopping breastfeeding altogether. It can also lead to families and the NHS unnecessarily paying for expensive specialist formula,’ said Robert Boyle, Consultant Allergy Specialist and lead author of the paper from Imperial College’s National Heart and Lung Institute.

According to the authors, milk allergy is most often found in children under the age of two and is divided into two types, one of which involves immunoglobulin E (IgE), and the other not. IgE-mediated allergies cause vomiting, hives and, in rare cases, a more severe reaction – breathing difficulties. Symptoms of non-IgE-mediated reactions can include vomiting, diarrhoea or excessive crying, and they are often confused with normal symptoms in babies.

‘In the nine guidelines we studied, seven of them suggested including milder symptoms as indication of non-IgE cow’s milk allergy, such as regurgitating milk, crying and rashes – but many of these symptoms are present normally in babies, and will get better with time. Non-IgE cow’s milk allergy affects less than 1% of infants whereas troublesome vomiting, crying or eczema each affect 15–20% of babies,’ explained Daniel Munblit, Associate Professor of Paediatrics from Sechenov University and first author of the article.

Previous research shows that over the past ten years, in at least a few countries (such as England and Australia), doctors have been recommending specialised formulas for children with allergies significantly more often. Knowing this, the researchers checked the guidelines for a possible conflict of interest among the authors and found that eight out of ten authors had reported links to formula manufacturers, and three of the guidelines were directly supported by formula producers or their marketing consultants.

‘Formula manufacturers may gain from promoting increased cow’s milk allergy diagnosis – by influencing practitioners and parents to use a specialised formula in place of a cheaper formula, and by potentially undermining women’s confidence in breastfeeding, so that specialised formula is used in place of breastmilk,’ noted Robert Boyle.

He added, ‘We must not only critically appraise our current guidelines, and dissociate the development of guidelines from those who may profit from them, but also ensure we are giving each family the best possible care by avoiding overdiagnosis of cow’s milk allergy.’