According to data from the Mayo Clinic, about 2% of adults and 6% of children have some type of food allergy. Those percentages may seem low, but in a population of over 300 million in the U.S. that translates to 6 million and 18 million individuals, respectively.
Like any other allergy, a food allergy occurs when the immune system overreacts to an allergen. In this case, the allergens are typically milk, eggs, peanuts, shellfish and a few other foods.
In response to contact or ingestion, the body releases an antibody called IgE (immunoglobulin E) since it sees the food not as nutrition, but a foreign invader. The antibodies stimulate the release of histamine, prostaglandins and other compounds that produce the symptoms.
Food allergy symptoms tend to be more extensive than those that mark other allergic reactions. Nasal congestion and watery eyes are possible. But they are more often accompanied or overwhelmed by hives (itchy red welts that form on the skin), swelling of the lips, tongue or throat, wheezing and even nausea and abdominal pain.
In severe cases anaphylactic shock can occur. Anaphylaxis is a systemic (overall body) allergic reaction. It involves drastically lowered blood pressure, constricted airways leading to breathing difficulty, dizziness and other serious symptoms. It comes on quickly and, left untreated, sometimes causes death, as many as 200 per year in the U.S.
In some cases, food allergy reactions are localized. Fresh fruits and vegetables cause some to experience tingling in the mouth. The cause is thought to be proteins similar to those found in ragweed pollen.
Differentiating between a food intolerance and a food allergy requires a professional diagnosis by an allergist.
A skin prick test can frequently determine whether or not a person actually has an allergy to certain foods. The doctor takes an extract of the suspect substance and exposes the patient by inserting a small amount under the skin with a lancet. The skin is observed for about half an hour to note any swelling or itching in reaction to the extract.
A blood test may be warranted. This measures the amount of IgE produced in response to consuming the suspect food. But it is not always definitive.
Lactose intolerance, for example, is caused by the genetically induced lack of the digestive enzyme needed to safely process cow’s milk. The symptoms may be similar, but this is not an allergy.
Eliminating the troublesome food from the diet and environment is the first and best line of defense. Those with an allergy to eggs simply shouldn’t consume eggs or egg products. Those sensitive to peanuts and peanut dust can generally avoid coming into contact with it.
Since there is no cure yet for food allergies, avoidance is the best medicine. However, symptom relief is possible when accidents occur. Antihistamines are advisable. It’s also good to have on hand an EpiPen or similar device that allows allergy sufferers to inject a small amount of ephinephrine during an emergency. This can stave off any serious attack of anaphylaxis.