The term food intolerance is an umbrella term for all unwanted symptoms or diseases associated with the consumption of specific food items. It is not synonymous with the term food allergy. Besides toxic reactions (food poisoning etc.) and digestive disorders with a structural cause (stomach resection, diverticulum, pancreatitis etc.), for targeted diagnostics in the case of food intolerances, first and foremost, a differentiation has to be made between immunological and non-immunological reactions.
|Enzyme defects||Malabsorption||Allergies||Autoimmune diseases||Pseudo-allergies|
|Laktose intolerance||Fruktose malabsorption||Typ I (Soforttyp)||Coeliac disease||Food additive|
|Fruktose intolerance||Phytosterin-Resorption||Typ IV (Spättyp)|
|Histamine intolerance||Kreuzallergien (Inhalationsallergene)|
The reactions that are non-immunologically-mediated actually make up the major proportion of all adverse reactions to food. Either they are the result of an enzyme deficiency, where carbohydrates contained in the food are not adequately digested, or their cause lies in absorption dysfunction – called malabsorption – where the carbohydrates are absorbed only to a limited extent in the small intestine. In both cases, carbohydrates find their way into the deeper part of the intestine where they are osmotically active and also lead to flatulence and diarrhoea due to bacterial decomposition. The immune system plays no part in these intolerance reactions, that is, all of the ingredients in the food are tolerated by the immune system. In the European population, the most common dysfunctions in the digestion and absorption of amines and carbohydrates are lactose, fructose, and histamine intolerance.
With immunologically-mediated food intolerances, all components of the ingested food can indeed be digested and absorbed by the organism, but particular food ingredients cause the immune system to be activated. The immune system of the affected person cannot therefore ensure tolerance of the food ingredients that are actually harmless. The adverse inflammatory responses that are triggered resemble those that take place also in the biologically useful defence against pathogens. Immunological food intolerances encompass the spectrum of food allergies and cross-reactions, the autoimmune-induced coeliac disease, and so-called pseudo-allergic reactions to food additives.