| The term 'food allergy' should be reserved for those | | | | in an unstable gut flora although it has also been |
| reactions where foods precipitate symptoms | | | | reported in patients with normal gut flora. Although |
| immunologically; classic allergic reactions are mediated | | | | products of fermentation serving as diagnostic |
| by IgE and occur rapidly after ingestion of a very | | | | markers may be discovered in these patients, at |
| small quantity of the food concerned. | | | | present no simple test for food intolerance exists. |
| Food, however, can also precipitate symptoms by | | | | There is popular interest in the suggestion that food |
| non-immunological mechanisms. If taken in sufficient | | | | intolerances are related to overgrowth of Candida in |
| quantity, pharmacologically active substances in food | | | | the colonic flora but, as there is no scientific evidence |
| (such as caffeine or vasoactive amines) can affect | | | | supporting this suggestion, treatment with antifungal |
| some patients, and there are those who lack the | | | | agents is not justified in patients who are not |
| necessary enzymes to metabolize substances such | | | | immunosuppressed. |
| as lactose in cows' milk. Enzyme deficiencies may be | | | | No reliable data are available as to the incidence and |
| also be acquired, for example after treatment with | | | | prevalence of food intolerance or allergy as a cause |
| monoamine-oxidase inhibitors. Such non-immunological | | | | of gastrointestinal problems, reflecting the lack of a |
| reactions are usually termed 'food intolerance'; larger | | | | specific diagnostic marker. Patients with 'unexplained |
| quantities of food are necessary to produce them, | | | | chronic gastrointestinal symptoms may be thought to |
| and they are usually of slow and insidious onset. | | | | have irritable bowel syndrome. Studies have indicated |
| Some food intolerance is probably caused by | | | | that in up to 50% of patients appearing to have |
| abnormal fermentation in the colon and it can follow | | | | irritable bowel syndrome, symptoms are caused by |
| gastroenteritis or antibiotic usage which has resulted | | | | food intolerance. |