A food allergy is due to an abnormal response of the immune system following ingestion of a food. Recent studies have indicated that up to 8% of children and up to 4% of adults have food allergies. Food allergies are more likely in patients with a parent or sibling suffering from food allergies. In addition, patients with other atopic disease (eczema, asthma, allergic rhinitis) are more likely to have food allergies, especially eczema.
At times, individuals can have adverse reactions to foods that do not involve allergen antibodies. These reactions can be caused by enzyme deficiencies such as lactose intolerance, toxins or bacteria in foods, food additives such as MSG, or sulfites. These types of reactions can be mistaken for food allergies, but they are evaluated and treated very differently.
It is critical to accurately diagnose food allergies because patients with true food allergies are at risk for potentially life-threatening reactions and need to strictly avoid that food. On the other hand, if a food allergy is incorrectly diagnosed then a patient may unnecessarily avoid foods which can adversely affect their quality of life.
Currently, eight foods account for nearly 90% of allergic reactions, including:
Hives (urticaria) and generalized itching
Swelling of eyes, lips, tongue and throat
Cough, wheezing and shortness of breath
Nausea, abdominal cramping, vomiting and diarrhea
Light-headedness, dizziness, fainting and drop in blood pressure
After obtaining a thorough history, your allergist may recommend testing to confirm an IgE-mediated allergy. Skin testing is performed in the office with results identified within minutes. In certain cases when skin testing cannot be performed or the results are not clear, blood tests may be ordered to look for IgE against the specific food. Therefore, testing is typically performed to only those foods with a concerning history.
Mammalian Meat Allergy
Allergy to mammalian meats (beef, pork, venison, lamb) is an IgE-mediated food allergy that presents with symptoms four to eight hours after ingestion of the food. This allergy is due to sensitization that occurs following a tick, chigger or red bug bite.
Pollen-Food Allergy Syndrome (Oral Allergy Syndrome)
Symptoms will include itching, burning and swelling of the lips, tongue, palate and throat immediately upon ingestion of fresh, uncooked fruits and vegetables, tree nuts, spices and shellfish. The reaction is due to the presence of certain proteins within these foods that cross react with proteins in pollens (including grasses, trees and weeds). Because the symptoms can be similar to those of true IgE-mediated food allergies, patients experiencing these symptoms should see a board-certified allergist for further testing.
There is currently no cure for food allergies. Once an IgE-mediated food allergy has been diagnosed by your board-certified allergist, complete avoidance of the food (or foods) will be recommended. Patients and parents will be instructed to read food labels in detail. In addition, eating out requires patients to ask servers for detailed lists of ingredients when menus are vague.
Once diagnosed with a food allergy, your allergist will provide you with a Food Allergy Action Plan and review the indications for antihistamines and epinephrine. Patients will be instructed to carry an epinephrine auto-injector with them wherever they go in order to always be prepared for a possible reaction. There is ongoing research for possible treatments for food allergies, but no long-term “cure” has been proven in studies to date.
While no “cure” currently exists for food allergies, in 2020, the FDA approved the first commercially developed product for peanut oral immunotherapy. Food oral immunotherapy (OIT) is the process of reducing a person’s sensitivity to foods that cause allergic reactions. OIT can be provided for other food allergies using readily purchased foods under the supervision of an experienced board-certified allergist using established protocols.