Intolerance Health Dictionary

This is divided into food aversion, where a person simply avoids a food they dislike; food intolerance, where taking the food causes symptoms; and food allergy, where the symptoms are due to an immunological reaction. Some cases of food intolerance are due to idiosyncrasy – that is, a genetic defect in the patient, such as alactasia, where the intestine lacks the enzyme that digests milk sugar, with the result that individuals so affected develop diarrhoea when they drink milk. Intolerance to speci?c foods, as distinct from allergy, is probably quite common and may be an important factor in the aetiology of the IRRITABLE BOWEL SYNDROME (IBS).

For the diagnosis of true food allergy, it is necessary to demonstrate that there is a reproducible intolerance to a speci?c food; also, that there is evidence of an abnormal immunological reaction to it. Occasionally the allergic response may not be to the food itself but to food contaminants such as penicillin, or to food additives such as tartrazine. There may also be reactions to foods which have pharmacological effects, such as ca?eine in strong co?ee or histamine in fermented cheese, or such reactions may be due to the irritant e?ect on the intestinal mucosa (especially if it is already diseased) by, say, highly spiced curries.

Testing blood and skin for food allergy is beloved of some alternative practitioners but, in practice, the results of tests do not necessarily agree with what happens when the food is taken. Therefore, a careful history is as useful as any test in making a diagnosis.... food intolerance

is due to lack in the INTESTINE of the ENZYME known as LACTASE which is responsible for the digestion of lactose, the sugar in milk. The result is that drinking milk or eating milk-containing products is followed by nausea, a sensation of bloating, or distension, in the gut, abdominal pain and diarrhoea. (Similar disturbances after taking milk may also occur in those who do not lack lactase but have an allergy to milk protein). Treatment is by means of a low-lactose diet avoiding fresh or powdered milk and milk puddings. Many can tolerate fermented milk products, as well as the small amounts of milk used in baking and added to margarine and sausages. However, infamts may have to be fed exclusively on a lactose-free formula as even breast milk may produce symptoms.... lactose intolerance

See coeliac disease.... gluten intolerance

lowered threshold or heightened sensitivity to the normal pharmacological action and dosage of a drug. It is unpredictable but there is some evidence of familial history.... drug intolerance