Delayed immunologic food reactions

Delayed onset reactions to ingested foods may be difficult to recognize, especially if days or weeks elapse before symptoms appear. More than one immunologic mechanism may be involved and it is often difficult to assess the relative importance of each. Because immunologic responses occur in many healthy subjects who readily tolerate a specific food, little importance can be ascribed to a particular immunologic test unless it is shown that at least 95% of normals with similar exposure do not have such a response. Each food contains multiple antigens and allergic individuals differ considerably both in their immune responses and in the clinical manifestations they display. Because of this, the recognition and management of delayed food reactions is complex and requires an awareness of documented food-related disorders. It is a fruitful area for future research.