hypersensitivity reaction to a food or food additive. It is by definition IgE-mediated, and it involves very specific downstream chemical mediators. IgE mechanisms account for the majority of immunologic reactions to food. Food allergy (hypersensitivity) is a more general term--it includes food anaphylaxis and is used to denote an immunologic reaction to food, whether it is IgE-mediated or the result of some other immune mechanism (Fig. 1). Food intolerance is a general term describing an abnormal physiologic response to an ingested food or food additive that is not proven to be immunologic in nature. This term encompasses idiosyncratic, metabolic, pharmacologic, or toxic responses to a food or food additive.