Food intolerance

Food intolerance (or non-allergic food hypersensitivity) is a detrimental reaction, often delayed, to a food, beverage, food additive, or compound found in foods that produces symptoms in one or more body organs and systems, but generally refers to reactions other than food allergy. Food allergies are immune reactions, involving mast cells in which food triggers release of mast cell mediators, such as histamine when the food allergen binds to pre-formed IgE antibodies already bound to the mast cell. This mechanism causing allergies to typically give immediate reaction (a few minutes to a few hours) to foods, There are numerous causes for other types of food sensitivities, most of which, in contrast to food allergies, cause delayed hypersensitivity reactions to the food.

Food intolerances can be classified according to their mechanism. Intolerance can result from the absence of specific chemicals or enzymes needed to digest a food substance, as in hereditary fructose intolerance. It may be a result of an abnormality in the body's ability to absorb nutrients, as occurs in fructose malabsorption. Food intolerance reactions can occur to naturally occurring chemicals in foods, as in salicylate sensitivity. Drugs sourced from plants, such as aspirin, can also cause these kinds of reactions. Finally, it may be the result of non-IgE-mediated immune responses.