Are food intolerances genetic

Intolerances and allergies

Food is a complex source of allergens and contains many glycoproteins that lead to an allergenic reaction and can also cause cross-reactions with one another (Table 1). The classic food allergies in infants and children are almost always triggered by proteins from milk, chicken eggs, nuts, soy, wheat and fish. Adults, on the other hand, react more frequently to allergenic structures found in nuts, celery, fruit, fish, legumes and soy (6, 7, 8).

Whether casein in cow's milk, ovalbumin or ovomucoid in hen's eggs or parvalbumin in fish: all allergenic structures identified so far have been recorded and standardized by the WHO (http://www.allergen.org). Allergenic components can react differently to heat, the pH value of the stomach and cleavage by pancreatic enzymes, so there are certainly protein structures that can withstand the effects of heat and retain their allergenic properties even after the food has been prepared. For example, parvalbumin's allergenic potential is retained when it is heated, so that many people are allergic to cooking vapors when preparing fish (9). But gastric pH and digestive enzymes also have to be overcome. Proteins that are stable in digestion are the true food allergens and are characterized by the fact that they can be absorbed in intact form via the gastrointestinal epithelium.

Adults are at increased risk of developing a food allergy if they are allergic to pollen and / or are atopic. This can be explained by the cross-reactive protein structures that occur in both pollen and food; this is referred to as a pollen-associated food allergy. Many foods contain proteins that are structurally similar to the pollen allergens of early flowering trees, herbs, grasses or grains. Oral allergy syndrome can not only make itself felt as swelling and tingling in the area of ​​the lips, tongue or throat, but can also lead to life-threatening complications due to narrowing of the airways (10).

Birch pollen allergy sufferers are most frequently affected by an allergic cross-reaction with apples or other fresh fruit, among other things. In addition to pollen, latex, insect venom or house dust mite allergies can also be the cause of a cross-reaction (Table 2).

A detailed anamnesis forms the basis for the diagnosis of food allergies. It is useful to create a nutrition and symptom diary over several weeks in order to identify possible triggers and to obtain information about risk factors. In addition, skin tests such as the skin prick test with native foods or commercial extracts can provide information that is supported by a serological IgE determination of the most important allergens. An oral provocation test, which must always be carried out under medical supervision, can be carried out to check the correspondence of diagnostic parameters and clinical symptoms.

Celiac disease, a special case

Celiac disease is a lifelong hypersensitivity to the adhesive protein gluten, which leads to chronic inflammatory bowel disease in people with a genetically determined risk. The prevalence of celiac disease in Germany is around 0.3 percent. The number of unreported cases is high. This is particularly fatal, since undiagnosed and untreated celiac disease is associated with an increased risk of developing additional autoimmune diseases such as diabetes mellitus and / or thyroiditis with continued exposure to gluten (11).