Food Allergy
Information on the causes, symptoms, and treatment of the abnormal reaction of the body to certain foods or their ingredients.
Symptoms and Causes
Food allergy occurs when the immune system responds excessively to a food, or one of its components, because it perceives it as harmful to the body, even though it is harmless. It is one of the most common types of allergy.
Although allergies can occur to a wide range of foods (around 70), the European Union has identified the 14 most common, which must be indicated on product labels to reduce accidental consumption of allergens by patients. These allergens are:
- Gluten-containing cereals (wheat, rye, oats, barley).
- Tree nuts (almonds, hazelnuts, walnuts, cashews, pistachios).
- Fish.
- Milk and dairy products.
- Soy.
- Crustaceans (crabs, lobsters, shrimp, prawns, langoustines, crayfish).
- Mollusks (mussels, clams, oysters, whelks, snails, octopus, squid, cuttlefish).
- Egg.
- Peanuts.
- Celery.
- Mustard.
- Sesame.
- Lupin.
- Sulfites (sulfur-derived compounds used as preservatives and antioxidants in certain foods and beverages. In wine, for example, they occur naturally after fermentation).
Although not included in this list, fruits can also trigger allergies, mainly peach, apple, plum, strawberry, kiwi, melon, and banana.
Food allergy can be classified into two types:
- IgE-mediated (immunoglobulin E): the immune system produces this protein to protect the body, but when generated in excess, it triggers a disproportionate response. The reaction occurs rapidly (within 2 hours) after consumption or oral contact with the allergen.
- Non–IgE-mediated: the body’s response involves other immune cells, such as mast cells, basophils, or T lymphocytes. Symptoms usually take longer to appear (up to 48 hours) and are generally less severe.
The prognosis of food allergies is variable. In some cases, they resolve over time (especially egg or milk allergies), while others persist into adulthood (particularly tree nut or peanut allergies).
Symptoms
The body’s response varies depending on the type of food allergy:
- IgE-mediated: the most characteristic symptoms are:
- Skin redness
- Urticaria
- Swelling of the lips or eyelids
- Vomiting
- Diarrhea
- Itching in the mouth or throat
- Rhinitis: congestion, runny nose, sneezing
- Asthma
- Non–IgE-mediated: the most frequent signs are:
- Abdominal distension (inflammation of the digestive tract)
- Abdominal pain
- Colic
- Diarrhea
- Vomiting
- Mucus in the stool
Causes
Food allergy results from an error of the immune system, which identifies harmless substances as harmful to the body.
Risk Factors
The risk of developing a food allergy increases in the following cases:
- Age: more common in children, affecting an estimated 4–6% of the pediatric population. In adults, incidence is 1–3%.
- Family history of allergies, urticaria, or asthma
- Allergies to other substances
- Asthma
- Eczema
Complications
The most significant complications of food allergy are:
- Anaphylaxis: a severe and potentially life-threatening systemic immune reaction. In addition to typical food allergy symptoms, at least one other vital organ shows signs:
- Shortness of breath, hoarseness, wheezing
- Arrhythmias, confusion, drowsiness, dizziness
- Anaphylactic shock: a severe form of anaphylaxis requiring immediate attention. It usually presents as:
- Hypotension
- Weak pulse
- Dizziness
- Loss of consciousness
- Death
Prevention
To prevent allergy, one should avoid consuming foods that trigger it. It is essential to check food labels carefully and exercise caution in restaurants.
Which doctor treats food allergy?
Food allergy is diagnosed and managed within the allergology specialty.
Diagnosis
Diagnosis of food allergy follows these steps:
- Medical history: information is collected regarding the patient’s general health, lifestyle habits, and personal and family medical history. Patient symptoms and the timing of their occurrence are also documented.
- Skin tests: a small amount of allergen is applied to the forearm using a minor prick to allow penetration. After a set period, changes in the skin are observed as a sign of allergic reaction.
- Blood tests: a blood sample is analyzed to detect the presence of antibodies.
- Oral food challenge: small amounts of the suspected allergenic food are administered in a controlled manner, gradually increasing the dose while monitoring for any reaction.
Treatment
Once a food allergy is diagnosed, the patient must completely eliminate the allergen from their diet. Allergic reactions are treated as follows:
- Antihistamines: usually taken orally. They relieve discomfort and urticaria in mild cases.
- Epinephrine: standard treatment in severe cases, administered via injection.
