Milk, the Most Commonly Undeclared Food Allergen Causing Unexpected Allergic Reactions in Sweden Between 2004 and 2011

Background: Allergy to milk proteins is a common allergic manifestation, especially among children. Different types of food products could be a risk factor for milk allergic individuals. According to the European Community Directive 2000/13/EC the list of ingredients shall include all the ingredients of the foodstuff, however with some exceptions. In 2003 Directive 2003/89/EC entered into force stating that milk and other ingredients, which are common elicitors of food allergic reactions, shall always be declared in the labeling.

Objective: To investigate which undeclared food allergen that most commonly has caused unexpected allergic reactions in Sweden between 2004 and 2011, i.e. since 2003/89/EC entered into force, and to compile data regarding the reactions to this food allergen.

Methods: The medical care, school personnel and control authorities have since 1990 been encouraged to report allergic reactions to foods, which do not declare the ingredient causing the allergic reaction, to the Swedish National Food Administration. Also, the suspected foods have been provided for analyses. Food allergens, e.g. caseins (a group of milk proteins), were analyzed with Enzyme Linked Immunosorbent Assay and/or Rocket Immunoelectrophoresis.

Results: Forty-eight cases of unexpected allergic reactions to foods, in which the causing food allergen was detected, were reported between 2004 and 2011. The most commonly detected food allergen was milk (21) followed by peanut (9), egg (6) and wheat (5). The persons who suffered from unexpected allergic reactions to milk were all children or teenagers. Mild symptoms were reported as well as anaphylactic reactions. One death was most likely caused by an allergic reaction to bread contaminated with milk. The lowest doses eliciting allergic reactions were calculated to be 2 to 6 mg casein. The types of foods causing the reactions were chocolate, ready-made meals, meat products, sauces, bread and a vegetarian milk substitute. The unexpected allergic reactions to milk were caused by mislabeling in 7 cases and to contamination in 14 cases.

Conclusions: Although rare, allergic reactions to undeclared food allergens may occur. Milk was the most commonly undeclared food allergen causing allergic reactions in Sweden between 2004 and 2011.