Food allergy
A food allergy is defined as an adverse immunological response to a food protein, this is separate to having a metabolic intolerance for a particular food (e.g. lactose).
Food allergies can be IgE mediated, cell mediated or a combination of the two. IgE mediated food allergies result from abnormal sensitisation to a food allergen that causes specific IgE production, once produced, the IgE binds on the mast cells, leading to mast-cell degranulation and release of mediators that cause the signs and symptoms of an allergic reaction. This can include anaphylaxis and oral allergy syndrome.
Meanwhile cell mediated reactions involve T-cells and are a delayed form of allergic reaction, occurring hours or days after ingesting the offending food. Diseases include food protein induced enterocolitis, enteropathy, proctocolitis and coeliac disease.
Mixed diseases include atopic dermatitis and the eosinophilic gastroenteropathy (e.g. eosinophilic oesophagitis).
Food induced anaphylaxis gives the familiar symptoms and is most commonly caused by allergens such as peanuts, tree nuts, shellfish and fish.