CausesBy Mayo Clinic staff
All true food allergies are caused by an immune system malfunction. Your immune system identifies certain milk proteins as harmful, triggering the production of immunoglobulin E (IgE) antibodies to neutralize the protein (allergen). The next time you come in contact with these proteins, these IgE antibodies recognize them and signal your immune system to release histamine and other chemicals. Histamine and other body chemicals cause a range of allergic signs and symptoms. Histamine is partly responsible for most allergic responses, including runny nose, itchy eyes, dry throat, rashes, hives, nausea, diarrhea, difficulty breathing and anaphylactic shock.
There are two main proteins in cow's milk that can cause an allergic reaction:
- Casein, which is found in the solid part (curd) of milk that curdles
- Whey, which is found in the liquid part of milk that remains after milk curdles
You or your child may be allergic to only one milk protein or allergic to both casein and whey. These proteins not only are present in milk, but they're also found in processed foods. Additionally, most people who react to cow's milk will also be allergic to sheep, goat and buffalo milk. Less commonly, people allergic to cow's milk are also allergic to soy milk.
- Atopic and allergic disorders. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec13/ch165/ch165c.html?qt=milk allergy&alt=sh. Accessed June 5, 2011.
- Food allergy: An overview. The National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodallergy/documents/foodallergy.pdf. Accessed June 5, 2011.
- Sicherer SH. Food allergens: Overview of clinical features and crossreactivity. http://www.uptodate.com/home/index.html. Accessed June 2, 2011.
- Tips to remember: Food allergy. American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/publicedmat/tips/foodallergy.stm. Accessed June 5, 2011.
- Schneider Chafen JJ, et al. Diagnosing and managing common food allergies: A systematic review. Journal of the American Medical Association. 2010;303:1848.
- Du Toit G, et al. Identifying and managing cow's milk protein allergy. Archives of Disease in Childhood: Education and Practice Edition. 2010:95:134.