Food allergies
What is it
Food allergies are an exaggerated response of the immune system by the consumption of a particular food . As Montserrat Fernández of the Allergy Service of the San Carlos Clinical Hospital in Madrid points out, the normal response of the immune system to food is to tolerate it. However, in some cases it generates an altered response that can cause harmful effects and reactions by the immune system that give rise to food allergies when people consume certain foods.
“The most frequent type of response is mediated by antibodies of the IgE type, which produce immediate reactions”, explains Fernández in the Allergic Diseases Book of the BBVA Foundation, edited with the endorsement of the Spanish Society of Allergology and Clinical Immunology . The specialist also points out that there are immune responses mediated by cells that elicit responses that manifest themselves later. These are usually cutaneous, such as atopic dermatitis, or digestive.
On the other hand, foods can also cause allergy if they are in contact with the skin or after exposure by respiratory route. In the first case they can cause dermatitis and urticaria, among others; while in the second they can generate problems related to the respiratory system, such as asthma or rhinitis.
The foods that most frequently produce allergy are milk, eggs, shellfish, nuts, wheat, legumes, soybeans, fruits and fish .
Allergy or intolerance?
In many occasions people confuse food allergy with intolerance. However, although they share similarities, as they cause harmful effects in the body due to the intake of certain foods, they are not the same.
Allergies are caused by an altered immune response to food, while in immune disorders the immune system does not intervene. The main causes of intolerance are usually due to alterations in the digestion and / or the metabolism of foodstuffs .
Incidence
Although society perceives that food allergies are a major health problem, only about one third of the reactions communicated by patients to the specialist can be confirmed in an allergological study.
According to Fernandez, of the results that have been obtained in epidemiological studies that show that there is a specific IgE response to a food by oral provocation tests, it is estimated that food allergy is between 1 and 3 percent of the population . “It is more common in children under 3 years, in which the incidence can reach up to 8 percent,” he says.
In recent years in countries like the United Kingdom and the United States has increased the frequency of allergies, especially related to nuts. Although in Spain there is currently no data on the prevalence of food allergy, the specialist indicates that in a decade the diagnoses have doubled , as indicated by the results of the Allergological studies conducted by the Spanish Society of Allergology and Clinical Immunology in 1992, 2005 and 2014.
Causes
Food allergies appear because there is a failure in the immunological tolerance for factors such as the genetic load of people, the state of the intestinal mucosal barrier, age or type, the amount and form of presentation of food , among others.
In the circumstances where tolerance fails, the immune system produces an IgE antibody response to food. The response begins in the intestine (although it can also manifest itself in other areas such as the respiratory system or the skin); in the respiratory mucosa and in the skin are some cells, the mast cells, to which the antibodies bind when the response is triggered. The antibodies can also attach to other cells, the basophils, which are circulating in the blood.
When the allergic person consumes the food that causes the reaction, the allergen is linked to the IgE that is found on the surface of basophils and mast cells. At that time it activates them and the release of histamine and other inflammatory substances that are responsible for the occurrence of allergic reactions.
symptoms
As specified by the specialist in Allergology, Montserrat Fernández, allergic reactions usually present the first manifestations in the two hours following the consumption of the food , although the most frequent is that symptoms appear in the first 30-60 minutes. “These reactions may involve one or several organs, including the skin, digestive tract, respiratory and cardiovascular system,” adds Fernandez, who notes that the severity depends on the patient’s immune response , the reactivity of the affected organ and of the characteristics of the allergen.
In addition, external factors such as the taking of steroidal anti-inflammatory drugs, the performance of physical exercise or the consumption of alcohol can aggravate the reactions.
The main manifestations that may appear are the following. All can be triggered associated or in isolation:
- Cutaneous : It is the most frequent reaction. Patients usually present urticaria .
- Mucous and pharynx : These symptoms are the second most common. Adults who have food allergies often have reactions in the oral mucosa and pharynx, known as oral allergy syndrome , such as rhinitis . In individuals with asthma bronchospasm can occur in the context of anaphylaxis (severe allergic reactions), this symptom can be very serious and can often cause death by allergic reaction.
- Digestive system : Finally, there are symptoms related to the digestive system that include diarrhea , abdominal pain, vomiting and nausea.
- Other symptoms include itching of the mouth , throat, eyes, skin or other area, difficulty swallowing, dizziness, fainting, swelling of the eyelids , face, lips and tongue or rhinorrhea. Among the symptoms of oral allergy include the itching of the lips, tongue and throat and swelling of the lips in certain cases.
Prevention
There is no effective way to prevent a food allergy; The main recommendation to avoid symptoms is to avoid consuming the food allergen.
Types
At present there are many types of food allergies. The most frequent are five:
1. Egg allergy
Chicken egg allergy is an adverse immunological reaction caused by consumption and contact with the egg. This type of allergy only develops in people who have produced IgE immunoglobulins directed against egg proteins. In these patients, every time they have contact with the egg an allergic reaction will occur.
The most common risk factors for egg allergy are family history, having previously allergic to another food or have atopic dermatitis.
This type is the most frequent in children older than 12 months with a prevalence in Spain between 0.5 and 2.7 percent of the general population in the first years of life. In fact, 44 percent of consultations for food allergy in children under 5 years is for the egg and in older than 5 years this figure is reduced to 10 percent.
After two years the cases in which the allergy occurs are very rare. In adults, the prevalence drops to 1 percent.
Symptom:
As explained by Elena Alonso, a specialist in Allergy and Pediatrics in the Allergy Service of the General University Hospital Gregorio Marañón, in Madrid, as in the rest of allergies, the symptoms of egg allergy can be very different and vary in manifestations mild, such as a slight itching of the mouth and / or throat , to more serious symptoms that may endanger the person.
“The symptoms happen in a short time, as much as an hour, after eating the egg. The most common are redness of the skin , itching , hives , swelling of the lips and eyelids . Nor are digestive symptoms with vomiting , abdominal pain and diarrhea uncommon , “he says before warning that less frequently appear respiratory symptoms that may be accompanied by difficulty breathing and swallowing. These are very serious so the patient should see the doctor at the time they start to occur.
Forecast:
70 percent of children allergic to eggs are cured . In fact, sometimes this occurs early. “At 24 months, 20 percent of children tolerate eggs,” explains Alonso, who points out that this figure rises to 30-35 percent at 3 years and 50-55 percent at 5 years. “Later, the evolution to tolerance occurs more slowly, until reaching 60-75 percent at 9 years.”
The prognosis to adulthood is still unknown.
Treatment and diet:
The treatment for people who have egg allergy is based on maintaining a diet free of this food and all products that may contain it. However, this option is often difficult to achieve, so specialists recommend that patients and family members know the symptoms and protocol of care that they should follow if they consume eggs.
Patients with this allergy may have problems following a diet because many products contain eggs without the consumer knowing about them and appear in other foods, such as sauces or confectionery products, and appear in places such as cosmetics.
2. Allergy to fish and shellfish
These two types of allergies are adverse reactions that occur due to a response of the immune system to a food. In these two cases, the immune response is mediated by IgE antibodies specific for fish and shellfish.
According to Ana Fiandor, a specialist in Allergy at the Allergy Service of the University Hospital La Paz, in Madrid, the allergy to fish is developed in countries with a high consumption of this food, such as Spain.
“The reactions occur in the first years of life and coincide with the introduction of fish into the diet, towards the first year of life,” says Fiandor. “In children it is the third cause of allergy and in adults it is responsible for 12-14 percent of cases of food allergy in Spain.”
Allergy to fish can last for decades, even a lifetime.
In the case of shellfish, this type of allergy is more common in adults than in children. Although, if it appears in children, it is usually very persistent.
Symptom:
The clinical manifestations that occur in the allergy to fish and shellfish are similar to those of other types of food allergies. Symptoms appear after consumption although in fish and shellfish they can appear only with the inhalation of cooking vapors or particles that break off in the handling of food.
Treatment:
The only treatment currently available is to follow a diet that does not include fish, shellfish and its derivatives and, in more serious cases, avoid spotting and exposure to vapors.
3. Milk allergy
Milk allergy is an adverse reaction of the organism to the proteins of this product. However, according to María Flora Martín, a specialist in Allergy in the Allergy Service of the University Hospital of La Paz, in Madrid, not all adverse reactions to milk are allergies.
This reaction usually has a hereditary base , so it can be transmitted from parents to children through the genes, although environmental factors are also involved in the development.
It usually appears in the first year of life. In Spain, one or two children out of every hundred develop milk allergy in the first year of life . In fact, in developed countries, the incidence is between 2 and 3 percent. “Most children lose their milk allergy throughout the first three years and, among the adult population, the clinical sensitization to milk is exceptional,” adds Martín.
Symptom:
The manifestations of this reaction are diverse, as well as the severity, which depends on the degree of sensitization and the amount of food you eat. In addition, the symptoms may worsen if the patient performs exercise, consumes alcohol or follows a pharmacological treatment.
The most frequent manifestations are the cutaneous manifestations , which appear in 70 percent of the reactions. They tend to be itching accompanied by redness of the skin with hives, hives, edema in areas such as the lips or eyelids, etc. In addition, pathologies such as atopic dermatitis usually get worse when the reaction occurs.
Other symptoms that usually appear are digestive: abdominal pain, vomiting, occasional diarrhea or difficulty swallowing. Finally, respiratory symptoms may appear, although they are less frequent, such as rhinitis or asthma .
Treatment and prognosis:
At present, the only effective treatment is the exclusion of milk of animal origin, its derivatives and products that may contain milk from the diet.
Most cases of this type of allergy occur temporarily and their prognosis is good in children . “More than 70 percent of those diagnosed in the first year acquire tolerance throughout the first three years. At one year, tolerance is established in 50-60 percent of children; at two years at 70-75 percent and at four years, at 85 percent, “explains Martín. “After 10 years, the allergy to cow’s milk proteins still persists in 10 percent of the initial cases. Evolution in adulthood is unknown. ”
4. Allergy to vegetables and fruits
Allergy to fruits is the most common cause of reactions to food in children over 5 years of age and in adults. According to the data from the Allergological study , 7.4 percent of people who come to the allergist have a food allergy. Of this percentage, 33 percent are allergic to fruits and 7 percent to vegetables.
The prevalence is subject to genetic factors (that a member of the family has allergies), environmental factors, such as eating habits according to the area or the presence of different pollens that can sensitize the individual.
The most allergic fruits and vegetables:
There are many fruits and vegetables that produce allergic reactions. In the case of fruits, the most allergic are Rosaceae. Of this family, the peach is the one that causes more allergies. Other fruits included in this group are the apple, the cherry, the pear, the apricot, the plum, the nectarine, the strawberry , etc.
In addition to these, other fruits that cause allergy are kiwi, melon, pineapple, watermelon, grapes, avocado and mango.
Regarding vegetables, the most allergic are vegetables, such as tomatoes, carrots, cabbage, lettuce, eggplant or pepper . Other vegetables that provoke reactions are onion, spinach, asparagus, as well as spices such as pepper or cumin, among others.
Symptoms and treatment:
The most frequent manifestations are the appearance of local symptoms such as itching, erythema labialis, swelling of lips and tongue , appearance of red spots or welts on the skin, dermatitis, among others. There may also be manifestations that affect the digestive and respiratory system.
As in other food allergies, the only effective treatment is the elimination of the fruit and / or vegetable from the diet.
5. Allergy to nuts, legumes and cereals
Reactions to vegetables within the group of cereals, legumes and nuts are very common in the allergist’s office. In fact, as stated by Ernesto Enrique Miranda, specialist in Allergology at the Allergy Section of the General Hospital of Castellón, nuts are the first cause of food allergy in adults and one of the first in age. childish.
The symptoms and treatments coincide with the rest of food allergies.
Cereals:
According to Miranda, the prevalence of allergy to cereals is low compared to other food groups, although it varies depending on age and geographical area. This type is frequent during childhood and usually disappears with age.
Vegetables:
Most legume allergies are due to the intake of soybeans, lentils, peas, chickpeas, green beans, lupins or beans.
This allergy is more common in the countries with Mediterranean diet , the Middle East, Far East and India. In Spain, pulses are in the fifth place of the foods that intervene in allergies in childhood, being rare in adulthood.
Nuts:
Peanut allergy is the most frequent. In the Anglo-Saxon countries it is considered a public health problem because 0.5 percent of the population is allergic to it and in 50 percent of the cases the reactions it produces are so serious that they can even cause death.
Hazelnut is the second dry fruit that produces the most allergy. In addition, in Spain nuts and almonds cause a lot of reactions.
Diagnosis
When the patient has suffered a reaction when consuming any food, the allergist Montserrat Fernández recommends that you consult a doctor. In these cases, the family doctor or the pediatrician will consider the symptoms of the patient and, if they are suggestive of allergy, refer them to the allergist.
Once in the specialist’s office, the specialist will collect a detailed clinical history of the reaction to try to establish which food or foods have triggered the reaction and establish a temporal relationship between the intake and the appearance of the symptoms to send the necessary tests to establish the diagnosis and confirm the IgE response to the food.
Treatments
Currently the only treatment against food allergy is the elimination of the product from the diet . “This recommendation seems simple, but nothing is further from reality,” says Fernandez. “A correct diet means that the patient carries a continuous surveillance in order to avoid exposure to the present and hidden allergens that appear in processed foods.”
For this reason, the specialist recommends monitoring and reading food labels and the exact composition of meals when they are made outside the home to avoid accidental poisonings.
In the last decades, specific treatments are being developed to try to modify the response of the immune system and to induce an oral tolerance in patients with persistent allergies. These treatments are known as oral desensitizations or oral immunotherapy or allergy shots, which could be promising for milk, peanut and egg allergy.
Other data
Tests for diagnosis
The cutaneous tests in some cases allow to diagnose a food allergy ; A positive result does not necessarily mean that a person is allergic to a particular food, but a negative result indicates that it is unlikely to be sensitive to that food. After a positive result in a skin test, the allergist may need to perform an oral test to arrive at the definitive diagnosis.
In an oral provocation test , the suspect food is hidden in another substance, such as milk or apple compote, and the patient ingests it. If no symptoms appear, the person is not allergic to that food. The best tests are “blind” tests ; that is, sometimes the food in question is mixed with another substance, and sometimes not. In this way, the doctor can determine with certainty if the patient has an allergy to that particular food.
An elimination diet can help identify the cause of an allergy . The person stops eating the foods that are presumably causing the symptoms. Later they begin to enter the diet one at a time.
The post Food allergies appeared first on HealthBodha.com.
