Allergy to Food

Reactions to food are common and can be divided into two categories: food allergy and non-allergic reaction to food. In this paper we talk about causes, symptoms and treatment of food allergy.

The distinction between the types of reactions to food is important, since they have degrees of severity and different treatments.

a.) Food allergy is an immune system reaction to one or more proteins of one or more types of food. Allergy to food can, in some cases, lead to severe anaphylaxis.

b.) Non-allergic reactions are reactions that are not caused by activation of the immune system, among them we can mention lactose intolerance, gastroesophageal reflux, stomach pain, food poisoning etc.

Food allergy
Food allergy
 


Food Allergy

Food allergy affects about 8% of young children and up to 3% of adults. Allergy to food has a strong genetic component and up to 70% of patients have positive family history.

The classic food allergy is the one that caused by the action of an antibody called IgE. Our immune system is programmed to fight any foreign substance that invades our body; however, there is a certain tolerance when these substances enter the gastrointestinal system. A patient allergic to a particular food has, in fact, an immune system that reacts disproportionately to the arrival of a particular protein, thinking that it is dangerous to an invading agent. A patient with food allergies usually has other types of allergies such as rhinitis, asthma, skin allergies etc., since the problem is the production of IgE, which is directed at inappropriate targets, i.e., proteins themselves are not harmful to the body. More than one third of children with atopic dermatitis also show some allergy to food.

For example, a patient allergic to seafood is actually allergic to one or more proteins present in these foods. Therefore, the shrimp allergic patient cannot tolerate other crustaceans, since proteins are very similar. By the same token, patients allergic to peanuts may also have a similar reaction to eating soy, peas or beans.

When one of these proteins reaches the digestive tract, the IgE antibodies mistakenly think that they are harmful to the body and trigger an inflammatory reaction in an attempt to destroy this invading agent. When IgE antibodies bind to a protein, they activate other immune cells such as mast cells (present in large amounts in the lungs, throat, skin, nose and intestines) and circulate in blood basophils. These cells produce chemicals such as histamine, the agent responsible for destroying invaders that ultimately end up causing the typical symptoms of allergy. The mechanism of food allergy is similar to, for example, allergic rhinitis.

The higher the body's reaction to the presence of a given protein, the greater is the release of chemicals from mast cells and basophils, and the greater the allergic reaction. In some cases the reaction is so disproportionate that puts the patient's life at risk causing anaphylaxis.


Symptoms of food allergy

Urticaria and angioedema
Urticaria and angioedema
 
The symptoms of food allergy appear within a few minutes after ingestion of food, but may take up to 4-6 hours. As there are lots of mast cells in the lungs, throat, skin, nose and intestines, allergic symptoms are often tied to these organs.

The most common symptom of an allergy to food is hives, and itchy red plaques usually located in the trunk. Another common symptom, but more dangerous, is angioedema, a swelling of the mucous membranes that usually show itself by swollen lips. Angioedema is serious when there is the swelling the tongue and throat mucous membranes, causing obstruction of the airflow to the lungs. The patient may stop breathing due to obstruction of the air.

Other symptoms of food allergy include rhinitis, conjunctivitis, asthma, diarrhea, abdominal pain and vomiting.

If there is a massive activation of basophils and mast cell reaction can be so strong that it may cause an exaggerated vasodilation, leading the patient to a state of circulatory shock known as anaphylaxis.


Oral allergy syndrome

The oral allergy syndrome, also known as pollen-food allergy, is a type of food allergy that affects up to half of patients with allergic rhinitis to pollen. These patients have allergy to raw fruits and vegetables which manifests itself immediately after eating them. The most common foods are bananas, cantaloupe, watermelon, apple, peach, plum, carrot, cucumber, squash, hazelnut, celery and others.


Food allergy after exercise

There is one type of food allergy that manifests only if the patient is engaged in physical activities until 4 hours after ingestion of certain foods. The patient with this type of allergy can eat shrimp and feel nothing, but if you eat it and enjoy some exercise you may even suffer an anaphylactic reaction.


Diagnosis of food allergy

Skin test reaction
Skin test reaction
 
Diagnosis involves a medical history, in which emphasis should be given to the food eaten before the reactions and the time it took for symptoms to emerge.

Skin tests can help. Here a doctor inoculates several types of proteins in the patient's forearm in search of the same reactions. The result usually takes only 15 minutes. The main test value is when it does not serve to eliminate the protein that does not cause a reaction. The positive test does not ensure that the patient is allergic to that protein.

In some cases with high risk for anaphylaxis, your doctor may choose to do this test with a risk of overreaction.

Currently it is possible to perform the measurement of specific IgE in the blood to identify against which one the patient develops food allergy.


Treatment of food allergy

No allergy
No allergy
 
The best treatment for food allergies is prevention. There is no treatment that can cure food allergies. The most important is to identify foods that cause allergy and avoid them permanently.

When the patient does not know the foods that cause allergy or when there is ingestion of a forbidden food, the treatment aims to control the allergic reaction. The most widely used drugs are antihistamines (antihistamines) and corticosteroids. In cases of anaphylactic shock treatment is the injection of adrenaline.

Patients with a history of anaphylactic reaction to food should wear bracelets or cards explaining their allergy so they can be quickly diagnosed and treated, if necessary. Many patients walk with automatic syringes of epinephrine if immediate treatment is needed.

Approximately 85% of children spontaneously stop being allergic to most foods (eggs, cow's milk, wheat and soybeans) between 3-5 years old. The skin test remains positive in spite of tolerance to food. Food allergy to peanuts, tree nuts, fish and shrimp rarely disappears.

General keywords

User discussion

Sarah
01 April 2012
Please help me! My husband has herpes, but it is not clear what type. There were three doctors who held a different treatment but nothing helps. First time he was injected - Tsikloferon seemed to help, but after 6 months period, when he decided to use Tsikloferon again, it didn't help. Different medications were prescribed but they did not work. (Cycloferon, Likopid, Famtsiuklovir, various ointments). Can you please tell us what to do, how to get rid of it!
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David
04 April 2012
My son is 5, he does not eat raw vegetables, fruit and cottage cheese. Can he "outgrow" this feature? In addition he has an allergy to medicine in syrups and antibiotics. Our allergist, though he has done all specific tests, cannot tell anything. He prescribed ketotifen for prevention. But it doesn't help. Do we have to contact a gastroenterologist?
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Paula
04 April 2012
My baby is 2 months. He is in the mixed feeding. He has red scaly patches on the cheeks, red pimples on the neck, and a crust on the head. The diagnose is "allergical dermatitis." Treatment: "Advantan", "Triderm", "Bepanten." The instructions to drugs say:contraindications for children under two years old. Isn't it a very severe treatment for a baby?
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Freddy
08 April 2012
For several years I've had a strong allergy to alcohol. The symptoms are: the redness of the face, red spots on the upper torso and arms, shortness of breath, and the heart rate - under 200, and vomiting. This reaction is absolutely unpredictable! It may occur, or may not. Does anybody know some blocker that I can take before drinking alcohol?
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Helen
07 May 2012
The illness occurs when I am nervous or when I do something physical, i.e, when the heart beats harder and when it gets hot...The whole body starts itching. The doctor said it was an allergy and prescribed Zirtek, I was taking it for one week, but no results... This allergy occurred to me three years ago, appeared only in winter, and this year is particularly harsh and hurts me every day, I even wake up at night because it becomes too hot and I start itching even in a dream... I do not know what to do.
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