New Test Beats Current Milk Allergy Detection

The BAT 2 milk study, funded by the UKRI Medical Research Council (MRC), looked at the accuracy of BAT in identifying cow's milk allergy compared to two routinely used allergy tests - the skin prick test and specific IgE measurement - in 150 children undergoing oral food challenges to cow's milk. The team found that BAT was more accurate at identifying children who reacted to oral food challenges than the skin prick or specific IgE tests, particularly in children under 2 years old. The results also showed that the use of BAT as a standalone test could reduce the need for oral food challenges, which are currently used in the clinic to confirm diagnosis.

Although BAT is not yet routinely used in clinical practice, the researchers believe that wider adoption of the test - which is also about five times cheaper to perform than an oral food challenge - could transform the diagnosis and management of cow's milk allergy.

A more accurate assessment of clinical allergy

Cow's milk allergy affects 2-3% of babies and young children¹ and is a leading cause of food-induced anaphylaxis. However, existing diagnostic tools often result in overdiagnosis, leading to unnecessary milk avoidance and related nutritional and developmental concerns.

Allergy tests can also be inconclusive, and oral food challenges - the consumption of small amounts of the allergen under close medical supervision - are often needed to confirm the allergy or whether the food can be safely reintroduced into the diet.

BAT is a laboratory test that measures how basophils (a type of white blood cell) in a blood sample react when exposed to allergens, such as milk proteins. Unlike traditional testing methods, which can lack precision, BAT offers a more accurate assessment of clinical allergy and could also offer a safer alternative to oral food challenges.

The research, published in the journal Allergy, represents the largest diagnostic investigation of BAT for cow's milk allergy to date. In the study, children were first offered an oral food challenge with baked milk, and those who tolerated baked milk were offered an oral food challenge with fresh milk. Among the children tested, 85% were able to tolerate baked milk, while 47% tolerated fresh milk.

Compared to the results of the oral food challenge, BAT was found to be particularly more accurate than the skin prick and specific IgE tests at predicting children who could tolerate baked milk, and at detecting fresh milk allergy, especially in children under 2 years of age.

For baked milk, out of 100 patients, 88 children were correctly diagnosed with BAT, compared to 69 with specific IgE and 64 with skin prick tests. Statistical analyses also showed that using BAT would significantly reduce the need for subsequent oral food challenges with baked milk to confirm diagnosis: per 100 children, 49 oral food challenges were required after BAT, compared to 88 after specific IgE and 100 after skin prick tests.

Introducing baked milk into the diet of children with cow's milk allergy has been shown to support the development of tolerance and reduce long-term dietary limitations. The findings suggest that BAT could play a crucial role in guiding safe reintroduction of milk into children's diets sooner, as well as helping to reduce the waiting times and costs associated with oral food challenges.

References

1. BDA - The Association of UK Dietitians. Milk Allergy, available at: https://www.bda.uk.com/resource/milk-allergy.html (accessed 10 July 2025)