eatrightPREP Domain 3 Practice Exam

True food allergy involves the immune system reacting to a food protein, most often via IgE antibodies. When exposed, these antibodies trigger release of mediators like histamine, leading to rapid symptoms such as hives, swelling, wheeze, or even anaphylaxis. Food intolerance is not immune-driven; it results from non-immune processes like enzyme deficiencies (for example, lactase deficiency in lactose intolerance) or sensitivities to additives, causing GI symptoms without immune involvement. This makes the statement that allergy is an immune-mediated (IgE) reaction the best distinction. The other choices describe intolerance or non-immune mechanisms, which don’t fit the true allergy–intolerance contrast.