Mechanisms in adverse reactions to food. The gastrointestinal tract.

Application of strict diagnostic criteria to celiac disease has led to the realization that there is a wide clinical spectrum within this disease. Normally there are immune reactions to dietary proteins, particularly secretory antibodies of IgA class, low titers of serum antibody and specific down-regulation of IgE and T cell reactivity (oral tolerance). From time to time, abnormal immunity to foods, either as inappropriately high titers of antibodies or qualitatively altered responses, produce disease. Lactase deficiency, with dose-related lactose and milk-intolerance, occurs in 50-90% of most populations. White, western Europeans are the exception.