Food allergies are on a rise in the United States. It is estimated that 1-3% of patients have food allergies, if not more. Food allergies are slowly being understood by patients and affect the quality of life.
Definition and prevalence
Food allergy is defined as an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food.
There are over 170 types of food allergies now. Most studies have focused on the most common food allergies such as hen’s eggs (hereafter referred to as eggs), cow’s milk, peanuts, tree nuts, soy, wheat, fish, and crustacean shellfish. Allergic reactions associated with these foods are typically caused by proteins that elicit specific immunologic reactions.
A number of specific clinical syndromes may occur as a result of food allergy. The most serious is anaphylaxis, which occurs in about one to 70 per 100,000 persons in the general population, and in 13 to 65 percent of suspected food allergy cases. Asthma and atopic dermatitis are associated with food allergies, but a causal link between food allergies and these disorders has not been established.
The time course of food allergy resolution in children varies by food, and may occur as late as the teenage years.9–12. By adolescence, 85 percent or more of children who have allergies to cow’s milk will tolerate cow’s milk, and up to 70 percent will outgrow egg allergies, but only about 20 percent will eventually tolerate tree nuts and peanuts.
A high initial level of allergen-specific IgE against a food is associated with a lower rate of resolution of clinical food allergies over time. Food allergies in adults can reflect persistence of childhood food allergies or de novo sensitization to food allergens encountered after childhood, most commonly seafood. Although there is a shortage of data from U.S. studies, food allergies that start in adult life tend to persist and not resolve.
Atopic dermatits, asthma, and food allergy
Family history of atopy and the presence of atopic dermatitis are risk factors for the development of sensitization to food allergens and the development of food allergy. Asthma, however, is a stronger risk factor.
Food allergies may coexist with asthma, and asthma is the risk factor most commonly associated with severe food allergy. Patients with food allergies and asthma have higher rates of emergency department visits and hospitalizations for asthma, and also have a higher risk of death from exercise-induced anaphylaxis. Exercise-induced anaphylaxis typically occurs within 30 minutes or less, but sometimes up to six hours after ingesting a specific food, with symptoms beginning after initiation of exercise. In this syndrome, ingestion of the specific food and exercise are required. Either factor alone does not produce symptoms.
When should a food allergy be suspected?
Food allergy should be considered when there is anaphylaxis or any combination of the following symptoms: angioedema, pruritus, diarrhea, nausea, dizziness, hypotension, chest tightness, cough, dyspnea, laryngeal edema, and nasal congestion.
The only way to diagnose a true food allergy is through laboratory specific IgE testing. There are many other food allergy tests available, however, these are not recommended.
IgE testing laboratory tests must be correlated with the patient’s food allergy symptoms. If the IgE is high and then the patient has a documented food allergy, then the diagnosis is most likely to be confirmed.
Food allergy treatment is simply elimination and avoidance. If there are multiple food allergies, then referral to a nutritionist in necessary to you receive adequate nutrients.
If you ingest a food that causes and allergy, please make sure you have an epinephrine pen, antihistamines, and a bronchodilator with you.
So far, there is no good prevention for food allergies. Please visit your family physician to discuss your questions and concerns about food allergies.