Food allergies: causes, symptoms and effective treatment

Food allergies make life very difficult, because because of it you have to refuse a variety of products - oranges and tangerines, chocolate, nuts, shrimp, crabs and other delicious things.The worst thing for people with multiple allergies is that they have to eat a monotonous diet, always specify the composition of new dishes and carefully study labels in stores.But this is a mandatory measure, because food allergies are very dangerous.Sometimes it is manifested by ordinary urticaria, and sometimes - anaphylactic shock, which can lead to death.About what food allergy is and why it develops, as well as the main symptoms and methods of its treatment, we will tell in detail in the article.

Food allergy is called an abnormal, extremely pronounced reaction of the immune system to some food products, most often proteins. This is not a disease in the classical sense of the word, but a special state of the body, a pathological reaction due to the “wrong” work of the immune system.

Food allergy can occur in children (even infants), adults and the elderly. On average, its prevalence is 1-3% (the figure varies depending on the specific country). You should also keep in mind that this reaction is very often confused with food intolerance.

Classic examples of food intolerance are lactose or sulfite intolerance, aldehyde dehydrogenase deficiency (flushes after drinking alcohol), and fructose malabsorption.

Food allergy to a particular product develops in 2 stages:

• sensitization, or the formation of hypersensitivity of the body - it occurs at the first contact with the allergen. The immune system perceives it as a foreign “agent” - a threat and begins to produce specific antibodies (IgE), which are attached to certain cells of the immune system - basophils and mast cells;
• direct allergic reaction - in case of repeated and all subsequent contacts with this allergen, antibodies provoke the release of histamine, which is responsible for all the symptoms of allergy (from a minor rash to anaphylactic shock).

Such food allergies (IgE-mediated) are called immediate food allergies because their symptoms can appear within minutes or even seconds of eating the “culprit food”.

Types of food allergies

Oral allergy syndrome (OAS) and hypersensitivity to seafood or peanuts/nuts are considered the most common forms of IgE-mediated allergies.

SOA is also called pollen-food cross-allergy syndrome. It occurs frequently (according to some reports in 5% of people) and develops in response to contact of the oropharyngeal mucosa with raw fruits and vegetables and nuts. At the same time, eating cooked fruits and vegetables, as a rule, does not cause any symptoms.

Such an interesting allergy is explained simply. It is provoked by proteins contained in both pollen and food (fruits and vegetables, nuts). But, in addition to this, they can still cross-react. Usually these reactions are seen between the following groups:

• birch pollen - apples, carrots, cherries, peaches, pears, plums, kiwi, almonds, celery;
• grass pollen - peaches and oranges, melons, celery, tomatoes;
• ragweed pollen - zucchini, cucumbers, bananas and melons, sunflower seeds.

If these products are cooked - the food protein will lose its structure (denatured) and will not be able to cause an allergic reaction.

With allergies to seafood, a person usually has an abnormal sensitivity to either fish or shellfish. And only 10% of people have this allergy mixed.

Peanut and tree nut allergy usually occurs in childhood and persists into adulthood. It can occur in a mild form or in a very severe form.

Rare forms of IgE-mediated allergy include exercise-induced food anaphylaxis. In this case, symptoms appear only if physical activity follows the consumption of the “culprit food”. The same allergenic foods, but without exercise, as well as activity without subsequent food, cause absolutely no symptoms in a person. Diagnosing this form of food allergy can sometimes be very difficult.

Another unusual form of food hypersensitivity is delayed allergy to red meat. It also belongs to IgE-mediated allergy, but, unlike the other types, it does not develop immediately - usually after 3-6 hours. This form is caused by sensitization to the allergen alpha-gal (galactose-alpha-1,3-galactose), which is present in the tissues of most animals except Old World primates and humans.

Humans can become sensitized to alpha-gal through tick bites (e.g., Amblyomma americanum) or after taking the drug cetuximab (an anticancer drug). In case of hypersensitivity to alpha-gal, not only red meat, but also animal products such as milk or gelatin can trigger an allergic reaction.

Causes and risk factors of food allergies

The cause of the symptoms of food allergy is one - contact of the body with an allergen. A variety of factors can provoke a “breakdown” of the immune system.

The main risk factors for the development of food allergy include:

• genetic predisposition - in this case, parents do not necessarily have to suffer from food allergies, it is enough and just “aggravated allergoanamnesis” (bronchial asthma, hay fever, atopic dermatitis and others);
• age - in children this pathological reaction is more common than in adults due to the immaturity of the immune system. By the way, some types of allergies (for example, to milk, wheat and eggs) children can safely “outgrow”;
• certain skin conditions - atopic dermatitis is associated with a higher risk of developing food allergies. It is thought that this may be due to a disruption of the skin barrier and, consequently, hypersensitivity to allergens;
• environmental factors - high levels of pollution, as well as a “sterile” early childhood environment, can disrupt the immune system;
• certain occupations - people working in the food industry may develop occupational food allergies to fish, shellfish, wheat and other grain products, as well as fruits and vegetables. They are also often diagnosed with respiratory allergies (asthma, rhinitis);
• delayed introduction of certain foods - it is believed that exposing children to certain foods too late increases the risk of allergy to them;
• multiple tick bites, which we mentioned above;
• jellyfish “stings” - Japanese surfers who were repeatedly stung by jellyfish were observed to be more likely to develop an allergy to natto (fermented soybeans);
• use of certain medications (e.g., cetuximab, which contains the alpha-gal allergen).

Symptoms of food allergies

Food allergies in children and adults can present with a wide range of symptoms, from virtually imperceptible to potentially fatal (and they can cause death in minutes). As a rule, the first manifestations develop quickly - within 10-15 minutes (up to 2 hours), with the exception of delayed allergy to red meat. Its classic clinical picture - a person dines on meat, and suddenly wakes up in the middle of the night with hives and digestive disorders.

Possible symptoms of food allergies:

• skin - itching, hives or Quincke's edema, increased sweating;
• eyes - redness of the conjunctiva, itching, periorbital edema, lacrimation;
• nasopharynx and oropharynx - sneezing, nasal discharge, nasal congestion, metallic taste and itching in the mouth;
• respiratory system - hoarseness of voice, shortness of breath, rapid breathing, coughing, choking, skin lividity;
• heart and blood vessels - increased or slowed heart rate, heart rhythm and conduction disorders, decreased blood pressure, cardiac arrest;
• digestive tract - nausea and vomiting, abdominal cramps, stool disorders (diarrhea), abdominal bloating;
• nervous system - dizziness, loss of consciousness, anxiety, fear, feeling of impending death, convulsions.

In severe food allergies, anaphylaxis develops - an acute systemic reaction that is life-threatening. It can manifest as:

• angioedema of the larynx;
• bronchial spasm with choking;
• anaphylactic shock - a sharp drop in blood pressure, which can lead to death in a few minutes.

It is not difficult to recognize it - a person has hoarseness / hoarseness of voice, shortness of breath, he may complain of difficulty breathing or a feeling of suffocation, sharp weakness, dizziness. In 90% of cases, there is also swelling of the lips, tongue, or entire face. Often there is whistling when breathing (stridor). With a severe drop in blood pressure (hypotension), the person loses consciousness.

Health effects of food allergies

Food allergies can adversely affect the health of the entire body, but the gastrointestinal tract is most affected. Exposure to allergens can lead to both acute manifestations and the development of distant effects.

The effect of allergies on the GI tract:

• acute reactions - nausea and vomiting, abdominal pain, diarrhea;
• chronic manifestations - eosinophilic esophagitis (allergic inflammation of the esophagus), increased intestinal permeability syndrome (damage to the mucous membrane, which facilitates the entry of bacteria and toxins into the bloodstream), chronic intestinal inflammation;
• delayed effects - disturbances of the intestinal microbiota and its immune function, deficiency of certain vitamins and minerals (e.g. iron or calcium) due to impaired absorption, development of chronic colitis and other inflammatory pathologies.

How to recognize food allergies in children?

In general, food allergies in children manifest themselves in the same way as in adults, but in babies it is not always easy to recognize it immediately. Very often this reaction first occurs when introducing complementary foods.

The main symptoms of “children's” food allergies:

• Redness and peeling of the skin on the face, cheeks, neck, its itching;
• blisters resembling nettle burns;
• nausea and vomiting;
• colic in the abdomen, which is manifested by severe restlessness of the child and crying due to abdominal pain;
• diarrhea or constipation;
• the appearance of mucus and blood in the stool;
• nasal congestion (unrelated to viral infections or colds);
• wheezing, wheezing without other signs of acute respiratory infections (e.g., fever).

Anaphylaxis in babies is rare, but you should always be aware of it, as this condition is extremely dangerous for the child. The main anaphylactic reactions are:

• rapidly occurring swelling of the face, lips, tongue;
• marked difficulty breathing;
• sudden pallor, lethargy;
• loss of consciousness.

In infants, food allergies most often occur to cow's milk, eggs, wheat, fish.

When do I need to see a doctor?

A doctor should be consulted if the consumption of a certain food worsens your well-being or causes the appearance of symptoms (eg, rash, itching, etc.). Allergist will conduct a comprehensive examination and establish the exact cause of such manifestations - food allergy, intolerance, GI diseases or other pathology.

The main diagnostic tests for suspected food allergy:

• Skin tests - scarification (a small amount of allergen is applied to the skin and a microscratch is made) and prick tests (intradermal injection, a more accurate method). This is a fast and highly sensitive diagnosis, but it is not used in children under 2 years of age (according to other data - up to 3 years of age). Also, skin tests are uninformative for some foods (e.g., heat-treated foods) and may themselves provoke an allergic reaction;
• Blood tests - a test for total IgE (an increase in its level indicates an allergy, but does not specify to which product) and specific IgE (identifies a specific allergen). These tests are safe and can be performed at any age, but, unfortunately, sometimes give both false-positive and false-negative results;
• provocation tests are the “gold standard” of diagnosis, but are performed only in hospital due to the increased risk of anaphylaxis. Doctors inject the patient with potential allergens and assess the body's reaction;
• elimination diet - temporary exclusion of the suspected allergen product from the diet, and then reintroduction. If symptoms similarly disappear and then return - the diagnosis of food allergy is considered confirmed.

Without an accurate diagnosis of food allergy, it is impossible to alleviate the condition, so it is necessary to undergo all the examinations that the doctor prescribes, and only then start therapy.

How to treat food allergies?

Treatment of food allergies begins with proper nutrition. Here everything is simple: there are no “dangerous” products - no dangerous reactions. But the diet for allergies should not be monotonous, because any allergens can always be replaced by safe analogs:

• dairy products - soy, almond or coconut milk;
• wheat and gluten - rice, corn, potatoes or buckwheat;
• nuts - sunflower seeds or pumpkin seeds.

To restore normal digestion, probiotics and prebiotics should be included in the diet. They not only help the gastrointestinal tract to return to normal after an allergic reaction, but also play an important role in preventing the development of food and other types of allergies, especially in children. If foods (kefir, yogurt, fiber) are not enough, doctors may recommend pharmacy probiotics (Linex) and prebiotics (Lactulose, Inulin).

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Medications for food allergies

Different groups of medications are used for food allergies:

• antihistamines (loratadine, desloratadine, fexofenadine, cetirizine and others) - they are effective when an allergic reaction has already occurred, but does not proceed very severely. Antihistamine medicines for food allergies can be taken in the form of tablets, capsules, drops or syrups;
• glucocorticoid hormones (prednisolone, dexamethasone) - indicated for severe allergies;
• monoclonal antibodies (omalizumab) - these drugs block the immune response and minimize the manifestations of hypersensitivity even in contact with a dangerous product. A special preparation of peanut antigen in powder form is also used in the United States.

Food Allergy Prevention

If you already have a food allergy, the only way to protect yourself from an acute reaction is to avoid allergenic foods.

Please note: if you are overly sensitive, symptoms can occur even if you simply hold the “dangerous” product in your hands or inhale its particles (e.g., inhalation allergies to peanuts, flour, cinnamon).

In addition, some measures help to reduce the risk of developing food allergies:

• breastfeeding - it promotes the formation of normal intestinal microbiota and contains a number of antibodies / immunomodulatory components;
• timely introduction of complementary foods - it used to be believed that “dangerous” foods (eggs, fish, nuts) should be introduced as late as possible, but over time doctors have revised these recommendations. Early introduction of potential allergens, on the other hand, helps reduce the likelihood of food allergies;
• avoiding unnecessary restrictions - there is no evidence that eliminating foods from a mother's diet during pregnancy or breastfeeding reduces a child's risk of allergies, so doctors now allow women to eat whatever they want (but within reasonable limits);
• maintaining the balance of intestinal microflora - proper nutrition, consumption of probiotics (e.g. fermented milk products) and prebiotics (fiber). The intestinal microbiota plays a key role in the formation of immune tolerance (the body's ability not to react with food allergies);
• reduction of exposure to harmful factors - polluted air, tobacco smoke, use of antibiotics strictly as prescribed by a doctor;
• observation by an allergist in case of hereditary tendency to food allergy - it is important for early detection of allergenic products.

In case of pollen hypersensitivity, it is important to remember the possibility of cross-allergy and to try potential allergenic products with caution (e.g. cherries and pears if allergic to birch pollen).

Overall, though, a comprehensive approach is important for both prevention and treatment of food allergies, from a balanced diet and vitamins to taking medications prescribed by an allergist.