Food allergies in children has become extremely common over the last number of years, with statistics showing that the number of diagnosed cases has increased 10 fold. Although there has been an increase in the number of people that are diagnosed with food allergies, it unfortunately is also a condition that is very commonly misdiagnosed.

Allergies are commonly defined by two terms; An IgE allergy and an non-IgE allergy. IgE allergies consist of a very rapid onset of symptoms that usually occur within 20-30 minutes of ingesting an offending food. In most cases, the reaction can in fact be as instant as a minute or two. IgE allergies can cause very serious symptoms such as difficulty in breathing, hives and swelling and in more serious cases, a reaction can lead to a life threatening anaphylactic shock.

According the World Allergy Organisation; “The term food allergy is used when an adverse reaction is due to an immunologic mechanism. Allergic reactions to food may be caused by antibodies in the blood or cells in the immune system. The IgE-antibody is responsible for immediate allergic reactions occurring after eating foods (known as an IgE reaction). Allergic reactions involving immune cells (which are known as T-cells) tend to be delayed reactions.” These type of reactions are known as non-IgE food mediated reactions.

Non-IgE allergic reactions are NOT caused by the IgE-antibody and is where misdiagnosis frequently takes place. Because of the lack of understanding of a non-IgE allergy and as there are no ways of carrying out a test for it, many groups of people (especially babies and children) are left undiagnosed and untreated for this condition. Non-IgE allergies are much more common in children than adults and reactions can range from very mild to very severe.

Non-IgE mediated reactions usually occur because of cell reactions in the immune system. When this happens, it involves the mast cells of the body (a mast cell is what is known as a “master regulator” of the immune system).

Each mast cell contains storage sacs known as secretory granules and they in turn contain biologically active molecules known as mediators. When a reaction occurs, these cells are known to degranulate and secrete causing allergic reactions and inflammatory diseases of the gut. These cells are located in connective tissue such as skin, lining of the stomach and intestine as well as areas of the gut. In some cases when degranulation of these cells occur within the gut, it can cause brush border damage to the cell walls of the intestines, allowing food to pass through these walls and out into other areas of the body, triggering an auto-immune (T-cell) response.

Unlike an IgE reactions, it can take anything from up to 2 hours to 72 hours (according to research at Great Ormond Street Hospital London) for symptoms of a non-IgE reaction to actually start to appear. Please see “Diagnosing Food Allergies” section for further information on symptoms.