It usually occurs in children, although at the same time the number of adults allergic to food is increasing. In adults, it can usually give signals from the skin – as a result of emerging swelling, rashes, atopic dermatitis – or the digestive system. Sometimes a food allergy is the result of chronic fatigue syndrome. How to diagnose it?
Food allergies are quite difficult to diagnose. There is no single method that will isolate the right allergen. It is usually diagnosed in several stages:
- First, the doctor interviews the patient,
- Then he orders tests that will show what the patient is allergic to.
Difficulties in diagnosing food allergy
Making a diagnosis is difficult because there are many factors that cause an allergic reaction. The total amount of products in the diet, the method of storing food, the amount of processed products are then taken into account. In addition, most patients are allergic to more than one allergen and, in combination with cross-allergy problems, diagnosis is very difficult.
Types of allergy tests
- Native tests – these are tests with fresh allergens – in this type of tests, fresh food products are applied directly to the skin.
- Provocation tests – this type of test is performed after the elimination diet. Provocation tests in food allergy are performed by gastroscopy: foods that are suspected of causing allergies are administered directly into the stomach and the patient’s reactions are observed.
- Skin food allergy tests – the basic set consists of 15-20 allergens, but it can be modified individually. The sets contain 15-20 allergens, among which we can find the main food allergens: flour, eggs, fish, milk; fruit and vegetable allergens – carrot, apple, strawberry, tomato; meat allergens – pork; as well as spice and cocoa allergens. Sets of this type of allergens can be adapted to the type of organism of a given person, individually modified. What is such a test? A drop of allergen is applied to the forearm or back, then the skin is punctured. Result: when redness and a blister appear after 15-20 minutes, the person is allergic to the given allergen. The first reaction reading is read after 48 hours, the second after another 48 hours.
- Blood tests (RAST) – most often they are performed for children who are less than 3 years old, as well as for people whose allergies are so strong that they are given antihistamines all the time. They consist in the determination of IgE antibodies for basic mold, mite, pollen and animal allergens. In people taking antihistamines, it is required to stop taking them 7-14 days before the tests. This type of test is also indicated for people who have a discrepancy between the history and the result of skin tests, as well as those who have severe allergic changes.