Food Allergies
What causes it?
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 bloodstream.
How does it happen?
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:
- Milk
- Egg
- Soy
- Wheat
- Peanut
- Tree nuts
- Fish
- Shellfish
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
- itchiness
- 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
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
- Illness
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
- 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.
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 a 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.