Food Allergy

Many people have the perception that they are allergic to foods. However, in reality only about 2% of adults and 8% of children are affected by food allergy.

Food intolerance is sometimes confused with food allergy. Food intolerance is an abnormal response to a food or food additive that is not an allergic reaction. It is different from an allergy in that it does not involve the immune system. An example of this is a lactose intolerance caused by intolerance to milk in which an individual lacks an enzyme to properly digest the sugar in milk.

With a true food allergy an individual's immune system will overreact to an ordinarily harmless food. Symptoms may occur even after consuming a tiny amount of the food. Food allergens are usually proteins. The most common food allergens responsible for up to 90% of all allergic reactions are the proteins in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

The most common allergic skin reaction to a food is hives. Gastrointestinal symptoms of food allergy include vomiting, diarrhea and abdominal cramping and sometimes a red rash around the mouth, itching and swelling of the mouth and throat.

In severe cases, consuming a food to which one is allergic can cause a life-threatening reaction called anaphylaxis - a systemic allergic reaction that can be severe and sometimes fatal.

Symptoms of anaphylaxis are reversed by treatment with injectible epinephrine, antihistamines, and other emergency measures.

As they grow older, some children may tolerate foods that previously caused allergic reactions with the exception of peanuts and tree nut allergy. Only 21% of patients with peanut allergy will outgrow it. Periodic food allergy check ups with appropriate food challenges should be carried out under the supervision of the allergist.

Atopic dermatitis or eczema, a skin condition characterized by itch, scaly, red skin, can be triggered by food allergy. This reaction is often chronic, occurring in individuals with histories of allergy or asthma. Asthma symptoms may be triggered by food allergy, especially in infants and young children. However, it is rare for asthma to be the only symptom triggered by foods in adults.

Food intolerance reactions are usually caused by factors in the diet other than proteins that make up food allergens. These symptoms may be due to chemicals in some foods. Symptoms can include nervousness after consuming caffeine in coffee or soft drinks, headaches triggered by chemicals in cheese, or preservatives added to foods. These additives may cause adverse reactions in sensitive people. However, the allergic reactions to food additives are very rare.

An allergist/immunologist is the best qualified professional to diagnose food allergy. The allergist will inquire about the frequency, severity and nature of the symptoms and will ask about the amount of time that elapses between eating a food and any reaction. Allergy skin tests or blood tests may be used to diagnose food allergy. Rarely, patch testing to foods may also be utilized to diagnose food allergy. Your physician may also suggest that you keep a food diary or eliminate certain foods from diet.

If the diagnosis of food allergy remains in doubt, the allergist may recommend a "blinded" food challenge to establish a cause and effect relationship between a food and an allergy symptom.

The best way to treat food allergy is to avoid the specific foods that trigger the allergy. The avoid eating a "hidden" food allergen away from home, food allergic individuals must always inquire about ingredients when eating at restaurants or in other homes. It is important for food allergic individuals to read food labels carefully and to become familiar with technical or scientific names for food and to be prepared for emergencies. Those who have experienced an anaphylactic episode to foods must carry and know how to use an injectible epinephrine.