Food allergy is a problem that affects a significant part of the population, but is more prevalent in infants and children. This problem is frequently encountered in allergy/immunology practices. There are a couple of important concepts to understand. Not all problems related to foods are actually allergic. There are also issues related to food intolerance (such as nausea, vomiting and queasiness). Other conditions that can be associated to foods include gastroesophageal reflux, symptoms related to lactose intolerance, and certain types of poisonings related to foods. Food additive reactions (such as with MSG, etc.) are frequently not allergic.
Headaches can be associated to chemicals released from foods, but usually do not involve allergic mechanisms. Allergic reactions to foods, in younger children, usually present with eczema. The main foods related in young children include wheat, egg, milk, peanut and soy.
More serious reactions can be termed “anaphylaxis” which usually involve more than one organ system. Typical signs and symptoms can include nausea, vomiting, skin rash, difficulty breathing and swelling of the throat. The most commonly implicated foods are peanut and other tree nuts as well as shellfish (although other foods are certainly possible).
There is a new diagnosis called eosinophilic esophagitis which can present with acid reflux symptoms. Difficulty swallowing or painful swallowing should be evaluated initially by a physician. Visual findings on endoscopy as well as biopsy findings confirm the diagnosis and these patients need an allergy consultation to consider food allergy.
Another new diagnosis is oral allergy syndrome, which occurs with various fruits and vegetables. This is usually manifested as mouth itching and is related to properties of these foods that “cross react” with different inhalant allergens.