Patients with food-related complaints pose a diagnostic challenge to their physicians because it is often difficult to document the underlying nature of the offending agent(s). Patients tend to report vague symptoms that are often chronic and delayed in onset. The patients generally fall into several distinct clinical groups: (a) patients with IgE-dependent mediated hypersensitivity allergic reactions, (b) patients who consume infected foods, (c) patients who consume food containing metals or toxins, and (d) infants on certain formulas.

Infants who receive hydrolysate formulas may develop necrotizing enterocolitis. This formula activates intestinal mast cells, thereby stimulating local immune mechanisms and inflammatory cells and increasing epithelial permeability (279). The mucosa becomes infiltrated with chronic inflammatory cells. Certain food additives induce GI disease via allergic reactions. Yellow dye No. 6, an artificial coloring found in candy, foods, and many drugs, serves as a GI allergen and results in allergic gastroenteritis with mucosal infiltration by large numbers of eosinophils (280,281).