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Food Allergy

Adverse reactions to foods are classified as being toxic or nontoxic.¹ Toxic reactions are not related to individual sensitivity but occur in anyone who ingests a sufficient quantity of tainted food. Examples of toxic reactions include reactions to histamine in scombroid fish poisoning or to bacterial toxins in food poisoning. In contrast, nontoxic adverse reactions to food depend on individual susceptibility and are either non­ immune-mediated--i.e., food intolerance alergy, or immune-mediated--i.e., food allergy. This article focuses on the clinical manifestations of food allergy.

Allergic Reactions

Skin

Urticaria
The skin is a common target organ for allergic responses to food. Acute urticaria is characterized by pruritic, transient, erythematous raised lesions, sometimes accompanied by localized swelling

Atopic Dermatitis
Atopic dermatitis usually begins in early infancy and is characterized by a typical distribution (face, scalp and extremities), extreme pruritus and a chronic and relapsing course. This inflammatory skin condition is frequently associated with allergic disorders (e.g., asthma and allergic rhinitis).

Dermatitis Herpetiformis
Dermatitis herpetiformis is a chronic papulovesicular skin disorder in which lesions are distributed over the extensor surfaces of the elbows, knees and buttocks.

Oral Allergy Syndrome
The oral allergy syndrome is characterized by pruritus and edema of the oral mucosa occurring after the ingestion of certain fresh fruits and vegetables.¹¹ The symptoms rarely progress beyond the mouth. The reaction occurs primarily in patients with allergic sensitivity to pollens and is caused by IgE.

Celiac Disease
A number of immunologic reactions to food proteins are not mediated by IgE. Celiac disease presents over a period of months with steatorrhea, flatulence and weight loss. Hypersensitivity to gluten.

Allergic Eosinophilic Gastroenteritis
Although allergic eosinophilic gastroenteritis is an IgE-mediated disease in some patients, about one half of patients do not exhibit specific IgE antibody to foods. Patients with allergic eosinophilic.

Infantile Proctocolitis
The symptoms of infantile proctocolitis are limited to the lower gastrointestinal tract and are of short duration. The ingestion of the responsible food (usually cow's-milk protein or breast milk.

Food Protein­induced Enterocolitis and Enteropathy
Patients with enterocolitis induced by food protein are often diagnosed in infancy and present with profuse vomiting and diarrhea. When severe, these symptoms may lead to lethargy, dehydration.

Rhinitis
The upper respiratory tract can be a target of IgE-mediated food allergy. Symptoms may include nasal congestion, rhinorrhea, sneezing and pruritus. The prevalence of food-induced allergic rhinitis.

Asthma
Food-induced asthma is an IgE-mediated illness that may result from the ingestion of a causative food.

Heiner Syndrome
An example of a non­IgE-mediated adverse pulmonary response to food is Heiner syndrome.

Anaphylaxis

Anaphylaxis refers to a dramatic multiorgan reaction associated with IgE-mediated hypersensitivity. Fatal food-related anaphylaxis appears to be more common in patients with underlying asthma symptoms.

Controversies and Food Allergies

The relationship of food allergy to a number of clinical entities remains controversial. Food allergy may play a role in a minority of patients with migraine headaches,²⁵ although the pharmacologic activity of chemicals found in some foods (i.e., tyramine in cheeses) is more often responsible.

The role of food allergy in childhood behavior disorders is also controversial.