Allergens are substances that cause an allergic reaction and it is difficult to avoid them in the normal way of life. They are all around us, in foods, medicines, dental products, cosmetics, nature and the environment we live in. Talking about food, food proteins are most commonly the main factor in triggering an allergies mechanism. Proper and healthy nutrition has become one of the most important problems of modern man. Someone may experience an allergic reaction even when avoiding food that he knows causes allergic reactions, but how is it possible?

A food allergy reaction is occurring when the immune system overreacts to a food or a substance in food (food allergen), identifying it as a danger and triggering a protective response. Food allergens are food fragments, mostly proteins, which pass through the intestinal mucosa, enter the blood and organs and cause allergies. Releasing of substances such as histamine, released from mast cells, causes tissue damage and gives us the full clinical manifestation of allergy. Mast cells are found throughout the body, but most of them are in the nose, pharynx, lungs, skin, central nervous system and digestive system. This is the reason why allergic reactions to food do not involve only the digestive system. Depending on which part of the body is affected, symptoms are:

  • Diarrhea, abdominal pains, vomiting and oral mucosal lesions such as aphthous stomatitis (digestive system)
  • Sneezing, respiratory depression, bronchial asthma (respiratory system)
  • Hives, eczema, angioedema, vasculitis (skin)
  • Migraine, tension syndrome, fatigue, decreased concentration (central nervous system).

If a person is very sensitive to an allergen, a greater number of organs will be affected by an allergic reaction. Due to damage of the blood vessels, fluids will leak into tissues and reduce the amount of circulating blood, which will cause a drop in blood pressure, airways constricting and the state of shock – anaphylaxis. Signs of anaphylactic shock are skin itching, lip swelling, nasal leaks, nausea, abdominal pain, vomiting, diarrhea, difficulty breathing unconsciousness, loss of consciousness and death.

Foods that most commonly causing allergies are cow’s milk, eggs, fish, crabs and shells, cereals, soybeans, peanuts, nuts, almonds, hazelnuts, and strawberries. In adults, about 90% of allergic reactions to foods are caused by peanuts, nuts, fish and mussels, and in children, eggs, milk, soya, and flour. Avoiding contact with the allergen is the only way a person can prevent allergic reactions. Sometimes that is not possible, not because of unwillingness to avoid specific kind of food, but because of unawareness that this kind of food is actually in the meal. We are talking about two food technology and sciences terms – cross contamination and cross-contact. While cross-contamination is connected tightly with transferring and spreading of bacteria and viruses from an object to a food, cross-contact is a physical transfer of food proteins from one place to another. Proteins can be transferred in various ways and break rooms; snack bars and restaurants are perfect places to do so. To illustrate, glucose oils are popular in cooking, including corn, peanut oil, olive oil, rapeseed, saffron, soybeans, and sunflower oil. Eating eggs will not cause any problem to people with celiac disease, but if eggs are fried in that oils, or there are oil traces on serving plate it can trigger an allergic mechanism at high gluten sensitive patients. There is no medicine that can be taken in the treatment of celiac disease. More precisely, there is no treatment, but the only chance for celiac sufferers is to lead a normal, healthy life by keeping diets that do not contain gluten. This means not using foods from wheat, rye, barley, oats, and other less well-known cereals. Many foods that cause allergy are found in larger or smaller amounts in other foods, such as eggs in biscuits, dressing salads or mayonnaise, or milk in ice cream. Proteins of two different related foods can also trigger an allergic reaction (cross-allergy), for example, if someone is allergic to mussels, the test will usually show that the person is not allergic only on that, but also to other types of shellfish, and even to the crabs as well. About 50% of patients who are allergic to cow’s milk are allergic to goat’s milk. In about 50% of patients who have taken soya milk due to allergy to cow’s milk, sensitivity develops on soy. The way of food preparing is also important. Some allergens from fish are thermostable; on the other hand, others lose allergenicity after heat treatment. Allergic reactions to fish are most often attributed to trout, salmon, white fish, pike, sardines and tuna. These reactions are more common in adults, in rooms where they consume larger amounts of these foods. A person may be allergic to just one type of fish or to fish of different species. Another example of cross allergies is also an oral allergy syndrome. Signs of oral allergy symptom are usually localized on the oral mucosa, but abdominal symptoms and anaphylaxis may occur as well. Because of in-mouth manifestations such as urticaria on the lips or on the buccal mucosa, itchy or edema of the lips, itchy pharynges, palate or gum, erythema of the face and feeling of tightness in the throat, patients connect it with adverse effects of dental products. Most dental products contain additives, fluorides, and even foods, but that is not the main reason for an oral allergy symptom occurring. Many products used in modern dentistry, such as prophy paste, are selected by a regulatory agency to ensure that there are ingredients that are safe and effective. By reading labels and ingredients, patients can avoid dental products which contain allergens and choose the safe one for them. Oral allergy syndrome is an antibody-mediated allergic reaction that occurs after consumption of fresh fruits and vegetables in patients with allergy to pollen. Symptoms arise due to cross-reactivity between pollen and plant-derived food and another term used for this syndrome is pollen-food allergy syndrome. The patient is sensitized with pollen and exhibits an allergic reaction to food antigen with structural similarity to the pollen.

An understanding characteristic and clinical presentation of food allergy can help with diagnosis. Different individuals have different levels of sensitivity and specific response to the presence of the same allergen. Reducing the risk of food allergies faced by consumers can be mitigated by timely identification of food products that contain substances causing allergic reactions, adequate control of the manufacturing process and storage of food. Verifying control by reading regulations and labels. Also, it is very important to educate people on preventive measures in controlling cross-contamination and cross-contact during the process of food preparing.