Every child knows that today: fruit, vegetables, dairy products and wholemeal bread are healthy. But it is also a fact that many people get complaints from it. They range from swelling in the mouth, sore throat, hives all over the body, drop in blood pressure to abdominal pain and diarrhea. The symptoms can occur individually or simultaneously. The reason is a food allergy or intolerance. The symptoms can be similar, but from a medical point of view the causes are very different.
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Allergies – the immune system reacts incorrectly
“The food allergy is caused by an overreaction of the immune system,” explains Prof. Dr. Ludger Klimek, Head of the Center for Rhinology and Allergology in Wiesbaden. “It classifies harmless substances in the food, such as protein, as enemies and forms larger amounts of special antibodies to fight them. They are directed against foreign proteins and trigger allergic inflammation in the body. This releases histamine, which causes the well-known symptoms.” The reaction can start within seconds. “The protein-related food allergy is the most common form. About six percent of children and three percent of adults are affected,” says Prof. Klimek.
While individual foods such as cow’s milk, chicken eggs or peanuts trigger an allergy in small children, the situation is different in adults. There is usually a cross allergy between pollen and certain types of fruit and vegetables. who e.g. B. gets hay fever from birch pollen is often allergic to peaches. In the case of severe reactions such as shortness of breath or circulatory collapse, the only thing that helps is to omit the food in question. In milder cases, the doctor may prescribe antihistamines or cortisone.
Food intolerances have other causes
Blame for the intolerance is not the immune system, but a metabolic disorder. This applies e.g. B. with histamine , milk sugar and fructose. Histamine is produced during the ripening of food. It is broken down in the intestine by the enzyme diamine oxidase (DAO). If there is a lack of DAO, histamine accumulates and leads to a rash and diarrhea. Also lactose intoleranceis due to an enzyme deficiency in the small intestine. As a result, the lactose reaches the large intestine undigested, where it ferments and causes colic and diarrhea. In acute cases, there are tablets for both intolerances that replace the missing enzymes. In the case of fructose intolerance, the absorption of alder fructose is disturbed, leading to flatulence and cramps. With celiac disease, the body cannot tolerate the gluten protein. The result is inflammation in the small intestine. Patients must strictly avoid gluten.
Kreuzallergie
Tree pollen contains proteins. They are similar to those found in fruits and vegetables. Therefore, the defense cannot distinguish them. Pollen allergy sufferers are plagued twice: with hay fever and with food allergies
Pollen | cross-allergenic foods |
| trees | Apple, pear, apricot, peach, plum, kiwi, mirabelle plum, passion fruit, plum, blackberry and nuts, especially hazelnuts. For vegetables, especially celery, carrots, potatoes, cucumbers, tomatoes, garlic, artichokes, peppers. Spices: anise, nutmeg |
| Grain/ grasses | Beans, peas, lentils, peanuts, soy, potato, chard, tomato, spinach. Fruits: honey and watermelons, kiwi, mangoes, papaya |
| Herbs | Anise, artichoke, basil, curry, dill, tarragon, fennel, carrot, celeriac, kohlrabi, caraway, marjoram, nutmeg, oregano, paprika, parsley, pepper, sunflower seeds |
Food allergy: This is how the doctor tests
Prick test
A drop of the allergen solution to be tested is pricked into the marked areas of the skin. If there is a visible reaction, the patient is sensitized and the “culprit” found. The skin prick test is the most common method.
Blood test
Anyone who is allergic to protein has an increased number of special antibodies in their blood. To determine this, blood is drawn from the patient and sent to the laboratory. If the values are elevated, an allergy is very likely. This test is considered very safe.
Provocation test
Here, the patient eats exactly the food that is suspected to be the cause of the symptoms. First in very small amounts. Because of the risk of severe allergic reactions, the test is performed under medical supervision.
food intolerance
Histamine test
Intolerance is detected by a blood test or an elimination diet. With the latter, the patient omits all histamine-containing foods for two weeks and checks whether the symptoms improve.
H2 breath test
This can be used to detect both lactose and fructose intolerance. The patient first drinks the appropriate solutions. Then the hydrogen in the patient’s breath, which the bacteria have produced, is measured.
Celiac disease test
If gluten intolerance is suspected, the blood is tested for transglutaminase antibodies. It is also tested whether there are antibodies against gliadins. They are gluten components found in wheat. Sometimes a tissue sample is taken from the lining of the small intestine.
