Food Allergy Update


by Cathy Green, M.D., Allergist and Immunologist

Allergy Chart


Research shows that children currently have more food allergy than at any time in the past. A  2008 Centers for Disease Control and Prevention report revealed that there has been an 18% increase from 1997 to 2007 in childhood food allergy1.  In this study 3.9% of children are currently affected. Children were most commonly allergic to cow’s milk, eggs, and peanuts.  Other common allergies include tree nuts (like cashews and walnuts), fish, shellfish, wheat, and sesame seeds.


One theory for this rise in childhood food allergy is that we live in a very clean environment. This theory is known as The Hygiene Hypothesis.  It is believed that living in an industrialized nation like the United States throws off our immune balance and leads to allergy.


In the past, children typically grew out of food allergies by 5 years of age. However, recent studies of allergic children indicate that only 11 % of these children grew out of their egg allergy and 19% grew out of their cow’s milk allergy by 4 years of age. In the same studies, 80% of children had grown out of egg and cow’s milk allergy by 16 years of age3,4. Peanut allergy is typically considered a persistent allergy. It can resolve in about 20% of young children by school age when their blood IgE levels to peanut show that the allergy is not very severe. However, peanut allergy may recur in some of these children once they start eating peanuts.


Food allergy means that the body produces an antibody called IgE (Immunoglobulin E) to certain foods. This antibody then binds to cells in the body called mast cells which are present in the lining of the nose, sinuses and airways, intestinal tract, skin and eyes.  When someone with a severe food allergy eats the food to which they are highly allergic, the IgE on the surface of the mast cells recognizes this food and becomes cross-linked which then causes release and production of a rush of allergic chemicals. These chemicals then cause the severe allergic reaction known as anaphylaxis. Symptoms of anaphylaxis include hives and swelling, difficulty swallowing, shortness of breath, wheezing, and vomiting. These symptoms can be life threatening. Children and adults with severe food allergy commonly require emergency room treatment and can require admission to the hospital. In the most severe cases, death will occur. Less severe food allergy can worsen underlying allergic conditions like asthma, atopic or allergic dermatitis, hives, and sinus allergies. It can also cause heartburn, diarrhea, gas and bloating.

Food allergies are diagnosed with specialized tests which include specific ImmunoCAP IgE blood testing and/or food allergy skin testing. The specific ImmunoCAP IgE blood testing results and the allergy skin testing results help to define the severity of the food allergy. Testing is necessary to define how strictly a food must be avoided and can help predict how severe the allergic reaction will be if the food is accidentally eaten.


Currently, the only approved treatment for food allergy is avoidance. In addition, it is also crucial to be prepared for a severe anaphylactic reaction if accidental ingestion should occur. Medicines like injectable epinephrine, Benadryl, prednisone and others will treat this type of reaction. Future treatments may include sublingual food immunotherapy (giving foods little by little under the tongue), food vaccines, Chinese herbal medicines, and anti-IgE antibodies.


In summary, food allergies are currently on the rise and are much more severe than at any time in the past. Blood and skin testing are necessary to help define the severity of the food allergy and the risk of anaphylaxis. The only currently approved therapy is food avoidance and immediate treatment when ingestion occurs. Thus, it is imperative that those with food allergy understand the severity of their condition and have an immediate action plan to prevent severe illness or even death should accidental ingestion occur.



  1. Branum A.M., Lukacs S.L.: Food Allergy among U.S. children: trends in prevalence and hospitalizations.  NCHS Data Brief 10. 1-8.2008.
  2. Sicherer, S. H., Sampson, H.A., Food Allergy. Journal of Allergy and Clinical Immunology - Volume 125, Issue 2 Suppl 2 (February 2010).
  3. Savage J.H., Matsui E.C., Skripak J.M., Wood R.A.:  The natural history of egg allergy.  J Allergy Clin Immunol 120. 1413-1417.2007. 
  4. Skripak J.M., Matsui E.C., Mudd K., Wood R.A.:  The natural history of IgE-mediated cow's milk allergy.  J Allergy Clin Immunol 120. 1172-1177.2007. 
  5. Sicherer S.H., Sampson H.A.:  Peanut allergy: emerging concepts and approaches for an apparent epidemic.  J Allergy Clin Immunol 120. 491-503.2007.