First, let's define allergy: It is an inappropriate reaction of the immune system to a substance (food in the case of food allergy). After a food is consumed, a reaction occurs through immune system cells and antibodies against that food or an additive in the food. If the reaction does not occur through the immune system, there can be no "allergy". (For example, reactions occurring with antibodies called IgE, lymphocytes, or more rarely, both antibodies and lymphocytes can be cited as examples of immunological reactions). Indigestion due to the inability to digest the lactose found in milk is not a milk allergy, but a reaction due to enzyme deficiency.
How Does the Immune System Work?
Our immune system recognizes the body's "own" tissues and proteins and recognizes "foreign" ones. It consists of cells that distinguish tissues, proteins, and microbes, and antibodies that help their functions. Normally, when a foreign protein (for example, bee venom, insect secretion in an insect bite, or bacteria in a vaccine) enters the body, cells and antibodies start to work; The bite site swells, "memory cells" develop in the vaccine against the bacteria that entered the body, and a reaction occurs against "that" substance. In food allergies, the body "accidentally" overreacts to a food substance that the body should not naturally perceive as "foreign". It produces excessive antibodies against that food substance or reacts with lymphocyte cells instead of producing antibodies.
A factor that makes diagnosis difficult in food allergies is that the symptoms may not appear immediately after food intake.
Sometimes the reaction occurs immediately after ingesting food, so it is easier to do a trial-and-error test for the relationship between the food and the allergic reaction. For example, I have many patients whose face turns red immediately after the spoon with yogurt touches their lips, and within 1-2 days, eczema develops, especially in these areas. It would not be difficult to say that they have ISA (Cow's Milk Allergy).
However, sometimes the immune system reacts to the food hours and sometimes even days later, in which case it becomes very difficult to diagnose. Try to make a diagnosis with long-term diets in children who cannot be linked to what they eat or drink.
In food allergies, especially ISA, allergies to more than one food can be seen. For example, if a baby with cow's milk allergy is also allergic to grains, especially sesame or wheat, it becomes more difficult to diagnose.
What are the symptoms of food allergy in children?
You can read a detailed article on this subject in our food allergies section. You can find it and reach it here...
In our medical practice, we can talk about 2 types of food allergies in general terms:
Nutritional
ReactionSymptomsImmunity
MechanismsDiagnosisEarly symptoms
(IgE-mediated)Redness, rashIgE production increases
and allergic
reactions beginIgE in the blood and
trial-and-error
methodLate symptoms
(non-IgE-mediated)Eczema, diarrhea,
growth retardation, without an increase in IgE, an allergic reaction occurs through the cells. Difficult
Source: Johansson EAACI Report, Allergy 2001; 56 (9): 813-24
For the curious
Type I reaction: IgE mediated
It is the most common and most researched reaction in food allergy. When antigen enters the body, large amounts of IgE are secreted from lymphocytes. This IgE goes and stimulates other immune cells. Substances that cause an early reaction are secreted from the stimulated cells, causing flushing, abdominal pain, cramps, vomiting, rash, drop in blood pressure, and cellular reactions that cause a late reaction begin. Skin tests are generally positive in IgE-mediated reaction. However, both skin tests and specific IgE levels may be falsely negative in children under 2 years of age. (In other words, although the patient is allergic, IgE is low and there is no response in the skin test.) However, since there are many positive cases, tests should be performed routinely on the patient.
Type II Cytotoxic Reaction
In food allergies It is a type of reaction that has no or very little activity. It occurs with immune substances called complement.
Type III reaction: Antigen-antibody complex
Research has detected activegen-antibody complexes in the blood of both normal people and those with food allergies. The level of these complexes is higher in people with food allergies. However, no definitive evidence has been found that these complexes cause food allergy. (SD)
Type IV reaction: Cell-mediated reaction
It is the reaction that occurs hours to days after food intake. It has been shown that the number of lymphocytes increases after food intake in many patients with food allergies. However, this increase can also be seen in those who do not have any symptoms of allergy.
Which foods cause the most allergic reactions?
Cow's milk
Cow's milk, It is the first foreign protein encountered in infancy and is one of the most common food allergies. It has been determined that cow's milk contains more than 25 proteins that have an antigenic effect on humans. The most important protein among these is beta-lactoglobulin. Other cow's milk proteins, to a lesser extent: alpha-lactalbumin, bovine serum albumin, cezein, etc. It may cause an allergic reaction. Goldman and his colleagues examined 85 children allergic to cow's milk with a provocation test; They found sensitivity to beta-lactoglobin in 62%, casein in 60%, alpha-lactalbumin in 53%, and bovine serum albumin in 52%. Only 50% of these children had a positive skin test. (SD)
Chicken egg
An important factor in food allergies is chicken egg. The main allergens found in egg white are ovomucoid and ovalbumin. Although egg white is more allergenic, gammaglobulin and avovitellin I in the egg yolk also show allergenic properties.
Fish and shellfish and shellfish (mussels, oysters, squid)
Fish is also harmful to both children and children. It is a food that can cause allergic reactions in adults. Its allergenic properties decrease with cooking. We see that not every fish may cause allergies, and a child who becomes red, swollen or vomits after eating some fish may not have an allergic reaction when eating another fish. Here again, it is necessary to apply the trial and error method to distinguish. However, a study has shown that proteins called "allergen M" or "Gad c I", consisting of 113 amino acids obtained from the white meat of cod fish, are resistant to both heat (i.e. cooking) and digestive enzymes, and that these common proteins are found in many fish. (SD) )
Some nuts
Wheat and grains
Globulin, glutenin and gliadin fractions found in wheat and other grains may cause allergic reactions. We also encounter more wheat allergies in our daily practice than expected. It has been shown that there is the most cross-allergy between wheat and rice and barley.
Peanut
Soy
Soy can cause allergic reactions, especially in children. Many of those who are allergic to milk are also allergic to soy.
Some of the fruits and vegetables
Allergy to cow's milk disappears around the age of 1-3, while allergies to hazelnuts, peanuts and seafood can last a lifetime.
Egg allergy and vaccines:
We encounter some concerns among the families of children who come to us that some vaccines should "never be given" to those with egg allergies. Because, for example, virus vaccines, especially measles-rubella-mumps and flu vaccines, are produced in chicken egg embryos. However, many studies have shown that these vaccines can be used safely in children with egg allergy. Moreover, it has been determined that the majority of children who develop anaphylaxis due to these vaccines do not have egg allergy.
Nevertheless, the American Academy of Pediatrics, Infectious Diseases committee recommends vaccination by taking precautions against allergic reactions and anaphylaxis before these vaccines
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Oh, is everything forbidden for life now?
This is the first reaction that occurs in families in food allergies, especially milk allergy: “Oh, oh, is everything forbidden for life now? “
But be aware that no... Yes, you will enter a difficult period that may last 1-2 years, but just because he cannot eat dairy foods (or hazelnuts, for example) does not mean that he cannot eat them for life. Also, being allergic to some foods does not mean that you will be allergic to other things. Your child may be able to eat things that another child cannot eat... You can make a nutrition list with your pediatrician and dietitian...
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