Food allergies cause the immune system to react abnormally when exposed to one or more specific foods such as milk, egg, wheat and nuts. People with this type of food allergy will react quickly, within a few minutes to a few hours. Immediate reactions are caused by an allergen specific IgE antibody that floats around in the blood stream.
Once an allergenic food is eaten, the protein is absorbed during digestion and enters the bloodstream. That food will cause symptoms throughout the body because IgE binds to the food protein and then activates the allergy cells to release histamine and other chemicals that are involved in the allergic reaction.
For example, if someone has an IgE-mediated allergy to the protein in milk, he or she may experience symptoms in the skin (hives), stomach (vomiting), lungs (coughing, wheezing), and circulatory system (decreasing blood pressure).
Who is at risk for food allergies?
Food allergies are common. Five percent of children under the age of five have a food allergy. Roughly 4% of adolescents and adults have a food allergy.
The prevalence of food allergies does seem to be increasing. Researchers believe many factors may play a role in food allergy development including maternal diet during pregnancy, timing of food introduction, anti-relux treatment during infancy, and breastfeeding status.
If someone comes from an “allergic family” — one that includes family members with asthma, environmental allergies and eczema — the person has an increased risk for allergy.
The most common food allergens include:
- Tree nuts
All of these foods can trigger anaphylaxis (a severe, rapidly progressive, life threatening allergic reaction) in patients who are allergic.
Symptoms of food allergies:
When someone has a food allergy, the body’s IgE antibodies identify that specific food as an invader and can produce symptoms in multiple areas of the body.
Skin: “hives” (red blotches or welts that itch), mild to severe swelling
Eyes: tearing, redness, itch
Nose: clear discharge, itch, congestion
Mouth: itch, lip swelling, tongue swelling
Throat: tightness, trouble speaking, trouble inhaling
Lungs: shortness of breath, rapid breathing, cough, wheeze
Stomach: repeated vomiting, nausea, abdominal pain, diarrhea (usually later)
Heart and circulation: weak pulse, loss of consciousness
Brain: anxiety, agitation, loss of consciousness
Diagnosing IgE-mediated food allergies
Receiving a diagnosis of food allergy may come in a few ways:
You or your child may have had a reaction to a food which led to an evaluation by an allergist. Your child may have had a flare of eczema, which led to concerns about a food allergy.You may have discussed concerns about your child with his or her pediatrician, who recommended consultation with a specialist.
When you meet with Dr. Jacobs, we will discuss the food reaction history, as well as get a detailed medical and family history.
Based on the history and findings, we may recommend testing and / or a food challenge.
Treatment for IgE food allergies
Reactions to food can be different every time. The reaction can depend on a variety of factors including:
- The amount of food eaten
- Uncontrolled asthma
In addition, the way the food was prepared and the amount of food protein ingested can affect the reaction.
Allergic reactions can occur quickly, so whenever more than one body system is involved in a food reaction (i.e. throat and skin); the best treatment available is Epinephrine. Epinephrine comes in a variety of forms including auto-injectors, such as Epi-Pen, Auvi-Q and other generic forms.
If the reaction is mild at first — and you’ve given an antihistamine — then the reaction quickly worsens, you should give epinephrine.
Children and adults with food allergies should always carry epinephrine with them, or it should be readily available at places where they routinely spend time such as school, daycare and home.
Oral Immunotherapy (OIT) is now offered by the The Center for Allergy & Immunology for treatment of food allergies.
Click here for more information on our Food Allergy Risk Reduction (FARR) Program, for infants who do not yet have a known food allergy but who are at higher risk of developing one.
Outgrowing food allergies
Some children with IgE-mediated food allergies will outgrow their sensitivity. For example, we know that milk, egg and soy allergies are more commonly outgrown during childhood and adolescence; while peanut and tree nut allergies are more likely to persist. Only about 20 percent of patients with peanut and tree nut allergies will outgrow them.
Not all children outgrow their allergies. Certain factors have been associated with the persistence of food allergies, including:
- Age of first allergic reaction
- Severity of allergic reaction
- Whether the child has asthma
- History of eczema
The majority of children with an egg allergy are able to tolerate cooked eggs as part of another food, such as cake (about two eggs per cake, heated at 350 degrees and cooked for 30 minutes). These same children typically would not tolerate a lightly heated egg, such as scrambled eggs or as part of French toast.
Similarly, many children with a milk allergy are able to tolerate small amounts of heated milk in other food products.
If your child is able to tolerate these heated forms, there is a better chance of outgrowing the allergy. A food challenge can be performed to the baked form of egg and milk.