Skin Testing With Ultra-Heat-Treated (UHT) Cow’s Milk in Children With Cow’s Milk Allergy

A majority of cow’s milk-allergic patients are able to tolerate extensively heated cow’s milk while remaining reactive to unheated milk because prolonged heat disrupts conformational epitopes recognized by cow’s milk specific immunoglobulin E and reduces allergenicity. Techniques used to improve the safety and durability of cow’s milk often involve heat; pasteurization involves heating milk to 72°C for 15 seconds and does not change the allergenicity of cow’s milk proteins. Another technique is ultra-heat-treated (UHT), prevalent in many countries outside the United States, which involves heating milk to 135°C for 1-2 seconds and allows for storage of unopened milk containers for prolonged periods without refrigeration. There are reports of patients counseled to ingest UHT cow’s milk as a substitute for unheated cow’s milk, presuming UHT processing may reduce the allergenicity of cow’s milk proteins. However, there are no documented reports of cow’s milk-allergic children safely tolerating UHT cow’s milk. The purpose of this study was to determine if skin testing using UHT forms of cow’s milk was significantly different from other forms of cow’s milk.

The study included 102 children with cow’s milk allergy living in Australia.

Subjects were recruited through a pediatric allergy clinic. Those included had a history of reacting to unheated cow’s milk and a positive skin prick test (SPT), defined as wheal size >3 mm, to commercial cow’s milk extract. Subjects who tolerated unheated cow’s milk or had no prior reactions to cow’s milk were excluded. Subjects then underwent SPT with commercial whole cow’s milk extract, casein extract, UHT milk, evaporated milk, and whole cow’s milk, with histamine and normal saline controls. Subjects were then challenged with unheated or heated cow’s milk based on treating physician’s assessment, and subsequently classified into three groups based on results of challenge: heated milk-reactive, heated milk-tolerant, and unheated milk-tolerant.

The study population had mean age of 4.98 years, 61.8% male, and high rates of other atopic diseases. After oral food challenges, 86% were tolerating some form of milk, with 72% tolerating heated milk only (heated milk-tolerant) and 28% tolerating both heated and unheated milk (unheated milk-tolerant). There was no difference in the mean SPT results for UHT cow’s milk between heated milk-tolerant and heated milk-reactive groups. For the unheated milk-tolerant group, mean SPT results were significantly lower for all the various forms of milk and extracts compared with unheated milk-reactive groups. Within the heated milk-reactive and heated milk-tolerant groups, there was no difference in mean SPTs for UHT compared with commercial whole cow’s milk extract.

UHT cow’s milk does not behave significantly different from other forms of cow’s milk in heated milk-allergic and heated milk-tolerant subjects, suggesting that the processing of UHT does not sufficiently alter cow’s milk proteins so as to be tolerated by heated milk-allergic children.

This study provides evidence that UHT cow’s milk is unlikely to be tolerated by patients who can tolerate heated cow’s milk but not unheated cow’s milk. Cow milk allergic patients who only tolerate heated cow’s milk should be counseled to avoid UHT milk.