Info about Food Allergies
Types of Food Allergens
There appear to be around eight foods, including those of both plant and animal origin, that are responsible for causing the majority of food allergies, namely peanuts and tree nuts, wheat, soya, cows’ milk, egg, shellfish, and fish. The geographical distribution of these allergies reflects patterns of food consumption with, for example, buckwheat allergy being much more common in the Far East, where they are staple foods, than is the case in Western countries. The distribution of allergies also differs across Europe, with reactions to fish and shellfish being higher in Mediterranean countries, where fish consumption is higher.
In addition to foods that sensitize individuals directly (probably via the gastrointestinal tract), there is a group of fruit and vegetable allergies that arise from the presence of cross-reactive epitopes in the allergens. Thus, individuals who become sensitized to pollen are more likely to develop IgE, which recognizes homologous proteins present in fresh fruits and vegetables. Around 70% of individuals who develop birch pollen allergy with IgE towards the pollen protein Bet v 1, develop allergies to apples and other fruits of the Rosacea because the anti-Bet v 1 IgE reacts with fruit homologs such as the apple protein Mal d 1. Similarly, many of those who develop allergy to latex have IgE, which recognizes the chitin-binding domain of the hevein polypeptides that make up the rubber latex network. An almost identical domain is found in a group of enzymes, the class I chitinases, found in a number of fruits including avocado, chestnut, and banana, which the anti-latex IgE recognizes. As a consequence of this cross-reactivity, individuals with latex allergy frequently suffer from allergic reactions on consuming these fruits.