Тағамдық аллергия: себептері, түрлері және алдын алу шаралары

Hypersensitivity reaction to a food

Common foods involved include cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy, wheat, and sesame. The common allergies vary depending on the country. The benefits of allergen immunotherapy for treating food allergies are not proven, thus not recommended as of 2015. Some types of food allergies among children resolve with age, including those to milk, eggs, and soy; while others such as to nuts and shellfish typically do not. They are more common in children than adults and appear to be increasing in frequency.

Allergic reactions are abnormal immune responses that develop after exposure to a given food allergen. Food allergens account for about 90% of all allergic reactions. The most common food allergens include milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat, which are referred to as "the big eight". In April 2021, President Joe Biden signed the FASTER Act into law. This landmark food allergy law recognizes sesame as the ninth mandatory food label allergen. It also encourages research that will improve the quality of life for food allergy families, and that could potentially lower the rates of future food allergies. Peanuts, a member of the legume family, are one of the most common food allergens that induce reactions in both children and adults. Affecting about 2% of the Western population, peanut allergies tend to cause more severe reactions and anaphylaxis than other food allergies. Tree nuts, including almonds, brazil nuts, cashews, coconuts, hazelnuts, macadamia nuts, pecans, pistachios, pine nuts, and walnuts, are also common allergens. Affected individuals may be sensitive to one particular tree nut or many different ones. Peanuts and seeds, including sesame seeds and poppy seeds, can be processed to extract oils, but trace amounts of protein may also elicit an allergic reaction. Egg allergies affect about one in 50 children but are frequently outgrown when children reach age five. Affected individuals can be sensitive to proteins both in the egg white and egg yolk, but most children are allergic to those in the white while most adults are allergic to those in the yolk. Cow's milk is the most common food allergen in infants and young children, yet many adults are also sensitized to cow's milk. Many affected individuals cannot tolerate dairy products such as cheese and yogurt. A small portion of children with milk allergy, roughly 10%, have a reaction to beef because it contains small amounts of protein that are also present in cow's milk. Shellfish, which are divided into crustaceans (shrimp, crab, lobster, etc.) and mollusks (mussel, oyster, scallop, squid, octopus, snail, etc. ), are the most common food allergy in adults. People may be allergic to other types of seafood, such as fish. Fish allergies were found to be more common in countries that have high fish consumption compared to those with lower consumption. Other common food allergens include soy and wheat. Those allergic to wheat may be sensitized to any protein in the wheat kernel. To a lesser frequency, people may be mildly allergic to raw fruits and vegetables, a disease known as oral allergy syndrome. and chemical additives. Balsam of Peru, which is in various foods, is in the "top five" allergens most commonly causing patch test reactions in people referred to dermatology clinics.

Exposure to certain food proteins triggers the production of antigen specific immunoglobulin E (IgE) antibodies, which, if unaccompanied by allergic symptoms, is known as allergic sensitization. Oral ingestion is the main sensitization route for most food allergy cases, yet other routes of exposure include inhalation and skin contact. Furthermore, peanut allergies are much more common in adults who had oozing and crusted skin rashes as infants, suggesting that impaired skin may be a risk factor for sensitization. An estimated 28.5 million people worldwide are engaged in the seafood industry, which includes fishing, aquaculture, processing and industrial cooking. In these occupational settings, individuals with fish and shellfish allergies are at high risk of exposure to allergenic proteins via aerosolization. Previous studies detected 40 allergens from wheat, some cross reacted with rye proteins and a few cross reacted with grass pollens. Allergic sensitization can occur via skin antigen exposure, which usually manifests as hives. The skin has been suggested to be a critical sensitization route for peanut allergic individuals. Several studies reveal that children exposed to skin creams containing peanut oil are reported to have a higher risk of peanut allergy, The syndrome has a strong inherited component; a family history of allergic diseases can be indicative of the atopic syndrome.

Some children who are allergic to cow's milk protein also show a cross sensitivity to soy based products. Some infant formulas have their milk and soy proteins hydrolyzed, so when taken by infants, their immune systems do not recognize the allergen and they can safely consume the product. Hypoallergenic infant formulas can be based on proteins partially predigested to a less antigenic form. Other formulas, based on free amino acids, are the least antigenic and provide complete nutritional support in severe forms of milk allergy. Crustaceans (shrimp, crab, lobster, etc.) and molluscs (mussel, oyster, scallop, squid, octopus, snail, etc.) are different invertebrate classes, but the allergenic protein tropomyosin is present and responsible for cross reactivity. People with latex allergy often also develop allergies to bananas, kiwifruit, avocados, and some other foods.

In the early stages of allergy, a type I hypersensitivity reaction against an allergen, encountered for the first time, causes a response in a type of immune cell called a TH2 lymphocyte, which belongs to a subset of T cells that produce a cytokine called interleukin 4 (IL 4). These TH2 cells interact with other lymphocytes called B cells, whose role is the production of antibodies. Coupled with signals provided by IL 4, this interaction stimulates the B cell to begin production of a large amount of a particular type of antibody known as IgE. Secreted IgE circulates in the blood and binds to an IgE specific receptor (a kind of Fc receptor called FcεRI) on the surface of other kinds of immune cells called mast cells and basophils, which are both involved in the acute inflammatory response. The IgE coated cells, at this stage, are sensitized to the allergen. If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils. Cross linking of the IgE and Fc receptors occurs when more than one IgE receptor complex interacts with the same allergenic molecule and activates the sensitized cell. Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators (cytokines, interleukins, leukotrienes, and prostaglandins) from their granules into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth muscle contraction. This results in rhinorrhea, itchiness, dyspnea, and anaphylaxis. Depending on the individual, the allergen, and the mode of introduction, the symptoms can be system wide (classical anaphylaxis), or localized to particular body systems. Cytokines from mast cells may also play a role in the persistence of long term effects.

Diagnosis is usually based on a medical history, elimination diet, skin prick test, blood tests for food specific IgE antibodies, or oral food challenge. Skin prick testing is easy to do and results are available in minutes. Different allergists may use different devices for testing. Some use a "bifurcated needle", which looks like a fork with two prongs. Others use a "multitest", which may look like a small board with several pins sticking out of it. In these tests, a tiny amount of the suspected allergen is put onto the skin or into a testing device, and the device is placed on the skin to prick, or break through, the top layer of skin. This puts a small amount of the allergen under the skin. A hive will form at any spot where the person is allergic. This test generally yields a positive or negative result. It is good for quickly learning if a person is allergic to a particular food or not because it detects IgE. Skin tests cannot predict if a reaction would occur or what kind of reaction might occur if a person ingests that particular allergen. They can, however, confirm an allergy in light of a patient's history of reactions to a particular food. Non IgE mediated allergies cannot be detected by this method. Patch testing is used to determine if a specific substance causes allergic inflammation of the skin. It tests for delayed food reactions. Blood testing is another way to test for allergies; however, it poses the same disadvantage and only detects IgE allergens and does not work for every possible allergen. Radioallergosorbent testing (RAST) is used to detect IgE antibodies present to a certain allergen. The score taken from the RAST is compared to predictive values, taken from a specific type of RAST. If the score is higher than the predictive values, a great chance the allergy is present in the person exists. One advantage of this test is that it can test many allergens at one time. A CAP RAST has greater specificity than RAST; it can show the amount of IgE present to each allergen. Researchers have been able to determine "predictive values" for certain foods, which can be compared to the RAST results. If a person's RAST score is higher than the predictive value for that food, over a 95% chance exists that patients will have an allergic reaction (limited to rash and anaphylaxis reactions) if they ingest that food. Currently, predictive values are available for milk, egg, peanut, fish, soy, and wheat. Blood tests allow for hundreds of allergens to be screened from a single sample, and cover food allergies as well as inhalants. However, non IgE mediated allergies cannot be detected by this method. Other widely promoted tests such as the antigen leukocyte cellular antibody test and the food allergy profile are considered unproven methods, the use of which is not advised. Food challenges test for allergens other than those caused by IgE allergens. The allergen is given to the person in the form of a pill, so the person can ingest the allergen directly. The person is watched for signs and symptoms. The problem with food challenges is that they must be performed in the hospital under careful watch, due to the possibility of anaphylaxis. Food challenges, especially double blind, placebo controlled food challenges, are the gold standard for diagnosis of food allergies, including most non IgE mediated reactions, but is rarely done. Blind food challenges involve packaging the suspected allergen into a capsule, giving it to the patient, and observing the patient for signs or symptoms of an allergic reaction. The recommended method for diagnosing food allergy is to be assessed by an allergist. The allergist will review the patient's history and the symptoms or reactions that have been noted after food ingestion. If the allergist feels the symptoms or reactions are consistent with food allergy, he/she will perform allergy tests. Additional diagnostic tools for evaluation of eosinophilic or non IgE mediated reactions include endoscopy, colonoscopy, and biopsy.

Breastfeeding for more than four months may prevent atopic dermatitis, cow's milk allergy, and wheezing in early childhood. Early exposure to potential allergens may be protective. The former guidelines, advising delaying the introduction of peanuts, are now thought to have contributed to the increase in peanut allergy seen recently. To avoid an allergic reaction, a strict diet can be followed. It is difficult to determine the amount of allergenic food required to elicit a reaction, so complete avoidance should be attempted. In some cases, hypersensitive reactions can be triggered by exposures to allergens through skin contact, inhalation, kissing, participation in sports, blood transfusions, cosmetics, and alcohol. Early introduction of peanut and egg alongside other solids, or by one year of age, may help prevent development of food allergy. Introduction of these allergenic foods within the first year of life appears to be safe. A window of opportunity for the introduction of different food allergens may exist, such as egg introduction ahead of peanut.

Allergic reactions to airborne particles or vapors of known food allergens have been reported as an occupational consequence of people working in the food industry, but can also take place in home situations, restaurants, or confined spaces such as airplanes. According to two reviews, respiratory symptoms are common, but in some cases there has been progression to anaphylaxis. The most frequent reported cases of reactions by inhalation of allergenic foods were due to peanut, seafood, legumes, tree nut, and cow's milk. One review mentioned case study examples of allergic responses to inhalation of other foods, including examples in which oral consumption of the food is tolerated.

Epinephrine (adrenaline) is the first line treatment for severe allergic reactions (anaphylaxis). If administered in a timely manner, epinephrine can reverse its effects. Epinephrine relieves airway swelling and obstruction, and improves blood circulation; blood vessels are tightened and heart rate is increased, improving circulation to body organs. Epinephrine is available by prescription in an autoinjector.

Antihistamines can alleviate some of the milder symptoms of an allergic reaction, but do not treat all symptoms of anaphylaxis. Antihistamines block the action of histamine, which causes blood vessels to dilate and become leaky to plasma proteins. Histamine also causes itchiness by acting on sensory nerve terminals. The most common antihistamine given for food allergies is diphenhydramine.

Glucocorticoid steroids are used to calm down the immune system cells that are attacked by the chemicals released during an allergic reaction. This treatment in the form of a nasal spray should not be used to treat anaphylaxis, for it only relieves symptoms in the area in which the steroid is in contact. Another reason steroids should not be used is the delay in reducing inflammation. Steroids can also be taken orally or through injection, by which every part of the body can be reached and treated, but a long time is usually needed for these to take effect.

Immunotherapies seek to condition the immune system to elicit or suppress a specific immune response. In the treatment of allergies, common immunotherapies seek to desensitize the immune system by gradually exposing the body to allergens in increasing amounts. These forms of immunotherapy have had varying and limited success and have generally been used to treat peanut and environmental allergies.

Omalizumab, an injectable asthma treatment drug sold under the brand name Xolair, was approved in the United States in February 2024 to reduce severe reactions to accidental exposure to food allergens. It is a genetically engineered monoclonal antibody which specifically binds to immunoglobulin E (IgE) to reduce the severity of an immune response. Successful results were reported for wheat, eggs, milk and baked products containing wheat and milk.

Food allergies affect up to 10% of the worldwide population, and they are currently more prevalent in children (~8%) than adults (~5) in western nations. Children are most commonly allergic to cow's milk, chicken eggs, peanuts, and tree nuts. An estimated 15 million people currently have food allergies in the United States. In 1997, 0.4% children in the United States were reported to have peanut allergy, yet this number markedly rose to 1.4% in 2008. In Australia, hospital admission rates for food induced anaphylaxis increased by an average of 13.2% from 1994 2005. Also, shellfish allergy is the most common cause of anaphylaxis in adults and adolescents particularly in East Asian countries like Hong Kong, Taiwan, Singapore, and Thailand. Another example is that, out of 9 European countries, egg allergy was found to be most prevalent in the UK and least prevalent in Greece.

About 75% of children who have allergies to milk protein are able to tolerate baked in milk products, i. e., muffins, cookies, cake, and hydrolyzed formulas. About 50% of children with allergies to milk, egg, soy, peanuts, tree nuts, and wheat will outgrow their allergy by the age of 6. Those who are still allergic by the age of 12 or so have less than an 8% chance of outgrowing the allergy.

In the United States, food allergy affects as many as 5% of infants less than three years of age and 3% to 4% of adults. The prevalence of food allergies is rising. Food allergies cause roughly 30,000 emergency room visits and 150 deaths per year.

Whether rates of food allergy are increasing or not, food allergy awareness has definitely increased, with impacts on the quality of life for children, their parents and their caregivers. In the United States, the Food Allergen Labeling and Consumer Protection Act of 2004 causes people to be reminded of allergy problems every time they handle a food package, and restaurants have added allergen warnings to menus. The Culinary Institute of America, a premier school for chef training, has courses in allergen free cooking and a separate teaching kitchen. School systems have protocols about what foods can be brought into the school. Despite all these precautions, people with serious allergies are aware that accidental exposure can easily occur at other peoples' houses, at school or in restaurants.

The value of allergen labeling other than for intentional ingredients is controversial. This concerns labeling for ingredients present unintentionally as a consequence of cross contact or cross contamination at any point along the food chain (during raw material transportation, storage or handling, due to shared equipment for processing and packaging, etc.). Experts in this field propose that if allergen labeling is to be useful to consumers, and healthcare professionals who advise and treat those consumers, ideally there should be agreement on which foods require labeling, threshold quantities below which labeling may be of no purpose, and validation of allergen detection methods to test and potentially recall foods that were deliberately or inadvertently contaminated. Labeling regulations have been modified to provide for mandatory labeling of ingredients plus voluntary labeling, termed precautionary allergen labeling, also known as "may contain" statements, for possible, inadvertent, trace amount, cross contamination during production. Precautionary allergen labeling can be confusing to consumers, especially as there can be many variations on the wording of the warning. Precautionary allergen labeling is optional in the United States. as of 2014, precautionary allergen labeling is regulated only in Switzerland, Japan, Argentina, and South Africa. Argentina decided to prohibit precautionary allergen labeling since 2010 and instead puts the onus on the manufacturer to control the manufacturing process and label only those allergenic ingredients known to be in the products. South Africa does not permit the use of precautionary allergen labeling, except when manufacturers demonstrate the potential presence of allergen due to cross contamination through a documented risk assessment and despite adherence to Good Manufacturing Practice. VITAL 2.0 was developed by the Allergen Bureau, a food industry sponsored, non government organization. The European Union has initiated a process to create labeling regulations for unintentional contamination but is not expected to publish such before 2024. In Brazil, since April 2016, the declaration of the possibility of cross contamination is mandatory when the product does not intentionally add any allergenic food or its derivatives, but the Good Manufacturing Practices and allergen control measures adopted are not sufficient to prevent the presence of accidental trace amounts. These allergens include wheat, rye, barley, oats and their hybrids, crustaceans, eggs, fish, peanuts, soybean, milk of all species of mammalians, almonds, hazelnuts, cashew nuts, Brazil nuts, macadamia nuts, walnuts, pecan nuts, pistachios, pine nuts, and chestnuts. and a 2016 U. S. National Academy of Sciences report concluded that there is no relationship between consumption of genetically modified foods and the increase in prevalence of food allergies,

One concern is that genetic engineering could make an allergy provoking food more allergic, meaning that smaller portions would suffice to set off a reaction. There are requirements in some countries and recommendations in others that all foods containing genetically modified ingredients be so labeled, and that there be a post launch monitoring system to report adverse effects (similar to the requirements in some countries for drug and dietary supplement reporting).

There exists both over reporting and under reporting of the prevalence of food allergies. Self diagnosed perceptions of food allergy are greater than the rates of true food allergy because people confuse non allergic intolerance with allergy, and also attribute non allergy symptoms to an allergic response. Conversely, healthcare professionals treating allergic reactions on an out patient or even hospitalized basis may not report all cases. Recent increases in reported cases may reflect a real change in incidence or an increased awareness on the part of healthcare professionals.

Food fear has a significant impact on quality of life. The social impacts of food allergies can carry over into adulthood.

Media portrayals of food allergy in television and film are not accurate, often used for comedic effect or underplaying the potential severity of an allergic reaction. These tropes misinform the public and also contribute to how entertainment media will continue to wrongly portray food allergies in the future. Types of tropes: 1) characters have food allergies, providing a weakness that can be used to sabotage them. In the movie Parasite a housekeeper is displaced by taking advantage of her peach allergy. 2) Food allergy is used for comedic effect, such as in the movies Hitch and in television, Kelso's egg allergy in That '70s Show 3) Food allergies may be incorporated into characters who are also portrayed as annoying, weak and oversensitive, which can be taken as implying that their allergies are either not real or not potentially severe. In season 1, episode 16 of The Big Bang Theory Howard Wolowitz deliberately consumes a peanut containing food bar (and has a serious reaction) just to delay Leonard from returning to his apartment where a surprise birthday party is being arranged. 4) Any of these portrayals may underplay the potential severity of food allergy, some showing that Benadryl treatment is sufficient. Viewing of humorous portrayals of food allergies has been shown to have a negative effect on related health policy support due to low perceived seriousness. A number of desensitization techniques are being studied. Areas of research include specific oral tolerance induction (also known as oral immunotherapy), and sublingual immunotherapy. The benefits of allergen immunotherapy for food allergies is unclear, thus is not recommended as of 2015. but the effects were not all sustained past 12 months. For infants, supplementing their diet with oils high in polyunsaturated fatty acids did not affect the risks of food allergies, eczema or asthma either as infants or into childhood. There is research on probiotics, prebiotics and the combination of the two (synbiotics) as a means of treating or preventing infant and child allergies. From reviews, there appears to be a treatment benefit for eczema, but not asthma, wheezing or rhinoconjunctivitis. The evidence was not consistent for preventing food allergies and this approach cannot yet be recommended. The Food Standards Agency, in the United Kingdom, are in charge of funding research into food allergies and intolerance. Since their founding in 1994 they have funded over 45 studies. In 2005 Europe created EuroPrevall, a multi country project dedicated to research involving allergies.