Food intolerance is a general term used to describe a wide range of adverse reactions to foods, including allergic reactions, adverse reactions due to enzyme deficiencies, pharmacological reactions, and other unspecified reactions.

IgE (Immunoglobulin E) is one of five immunoglobulins (IgM, IgG, IgD, IgA and IgE). It is the final product of the immunoglobulin family to be discovered. IgE not only has a unique chemical structure but also has many important physiological functions such as type I hypersensitivity reactions, parasitic infections, autoimmune processes, and is indispensable in the pathogenesis of allergic disorders.

Reactions to food are common and can be divided into two types: true food allergies and all other reactions. It is important to know the difference between food allergies and other types of reactions because each is treated differently.