Cow's milk allergies are overdiagnosed in babies and children

The current medical guidelines for testing babies and young children for cow’s milk allergies may lead to overdiagnosis, according to a new study led by Imperial College London. The experts determined that while only one percent of children are allergic to cow’s milk, as many as 14 percent of families believe they have a child with this condition. 

The investigation was focused on nine guidelines for cow’s milk allergies published between 2012 and 2019 across many countries, mostly in Europe. The team found that many of the symptoms listed as being indicators of a cow’s milk allergy, such as regurgitating milk and loose stools, are very common in healthy babies. 

After analyzing a recent European birth cohort study which involved over 12,000 infants in nine countries, the researchers determined that the condition has been frequently misdiagnosed. 

The study revealed that eight out of ten of all guideline authors reported a conflict of interest with formula manufacturers. The research suggests that prescriptions for specialist formulas developed for babies with cow’s milk allergies had increased significantly between 2000 and 2018, yet with no evidence of an increase in cow’s milk allergies.

Out of the nine guidelines examined for the study, seven specified that women who are breastfeeding a baby with a suspected cow’s milk allergy should cut out all dairy from their diet. However, the experts analyzed 13 studies of breastmilk composition which indicate that less than one millionth of the protein from cow’s milk travels through to breast milk. Upon further analysis, the team concluded that this amount is too low to trigger a reaction through breastfeeding for over 99 percent of children who are allergic to cow’s milk.

Study lead author Dr. Robert Boyle is an allergy specialist at Imperial’s National Heart and Lung Institute.

“Many infants who are labeled as having milk allergy don’t have the condition,” explained Dr. Boyle. “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 breast-feeding altogether. It can also lead to families and the NHS unnecessarily paying for expensive specialist formula.”

Milk allergies are most common in children under two, and they fall under two categories: IgE mediated and non-IgE mediated. An IgE mediated reaction can be very dangerous, with symptoms ranging from vomiting and hives to difficulty breathing.

The symptoms of non-IgE mediated reactions may include diarrhea, vomiting, or excessive crying. According to the researchers, the non-IgE mediated symptoms are often confused with normal conditions in young 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,” explained study first author Dr. Daniel Munblit. 

“Non-IgE cow’s milk allergy affects less than 1 percent of infants, whereas troublesome vomiting, crying or eczema each affect 15-20 percent of babies.”

Overall, 81 percent of all guideline authors reported that funding was received from formula manufacturers, which is a conflict of interest. Three of the guidelines were directly supported by formula manufacturers or marketing consultants, who stand to make a profit.

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

“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.”

The study is published in the journal JAMA Pediatrics.

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By Chrissy Sexton, Earth.com Staff Writer