Clinical Manifestations of Food Allergy

Adverse reactions to foods are a diverse group of clinical syndromes resulting from immunologic and non-immunologic responses to food ingestion. Symptoms can range from mild, self-limiting reactions to severe, life-threatening reactions depending on the mechanism. This review primarily focuses on the clinical manifestations of immunologically derived adverse food reactions or food allergies. The true prevalence of food allergy is unknown. Up to 25% of the general population believes that they may be allergic to some food; however, the actual prevalence of food allergy diagnosed by a provider appears to be 1.5% to 2% of the adult population and approximately 6% to 8% of children. This discrepancy makes it imperative that clinicians are aware of the different food allergy syndromes. With a clear understanding of the clinical manifestations of food allergies, an accurate diagnosis and treatment plan can be formulated. Failing to do so may result in unnecessary dietary restrictions that may adversely affect nutritional status, growth, and quality of life. Most food allergic reactions are secondary to a limited number of foods, and the most common foods causing allergic reactions in children include milk, egg, peanuts, tree nuts, and fish. In adolescents and adults, allergies to peanuts, tree nuts, fish, and shellfish are most prevalent. Food allergies can result from immunoglobulin E (IgE)-mediated, non-IGE-mediated, or mixed IgE/non-IgE mechanisms. The purpose of this review is to discuss the clinical manifestations of each of these types of food allergy.