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Food Allergy

Approximately 8% of children aged below 5 and around 4% of adults are believed to be impacted by food allergies. Although there is no known cure for food allergies, some children may eventually outgrow them as they age.

What is food allergy?


Food allergy is an abnormal immune system response that occurs when certain proteins in specific foods are mistaken as harmful invaders. This triggers the immune system to produce a defensive response, leading to a wide range of symptoms, varying from mild to severe, and in extreme cases, it can even be life-threatening. Digestive problems, hives, and swollen airways are among the various symptoms that may arise after consuming even a small amount of the allergenic food.


Food allergies impact approximately 8% of children under 5 years old and up to 4% of adults. Although there is no known cure, some children may eventually outgrow their food allergies as they age.


It is crucial to distinguish between a food allergy and a more common condition known as food intolerance, which is milder and not related to the immune system. Proper awareness, avoidance of allergenic foods, and preparedness for emergencies are essential for managing food allergies effectively.


What are the symptoms of food allergy?


The severity of an allergic reaction to a specific food can vary from person to person. While some individuals may experience discomfort without severe consequences, others may face frightening and potentially life-threatening reactions. Typically, food allergy symptoms manifest within a few minutes to a couple of hours after consuming the allergenic food, but occasionally, symptoms may be delayed for several hours.


The most frequent signs and symptoms of a food allergy include

  • sensations of tingling or itching in the mouth,

  • the appearance of hives, itching, or eczema on the skin,

  • swelling of the lips, face, tongue, throat, or other parts of the body,

  • respiratory issues like wheezing, nasal congestion, or breathing difficulties,

  • gastrointestinal problems such as abdominal pain, diarrhea, nausea, or vomiting,

  • and feelings of dizziness, lightheadedness, or fainting.


What is anaphylaxis?


Anaphylaxis is a severe allergic reaction that can be induced by a food allergy in certain individuals. This life-threatening condition gives rise to alarming symptoms, such as the constriction and tightening of the airways, a swollen throat or the feeling of a lump in the throat, which can lead to difficulty breathing. Additionally, anaphylaxis may cause shock with a significant drop in blood pressure, rapid pulse, dizziness, lightheadedness, or even loss of consciousness.


Immediate and emergency treatment is crucial when dealing with anaphylaxis. If left untreated, this condition can progress to a coma or potentially result in death.


What are the causes of food allergy?


When someone experiences a food allergy, their immune system mistakenly identifies a particular food or a component within that food as a harmful substance. Consequently, the immune system activates specific cells to release an antibody called immunoglobulin E (IgE) in an attempt to neutralize the allergenic food or its components.


Upon subsequent exposure to even a tiny amount of the triggering food, the IgE antibodies detect it and send signals to the immune system to release various chemicals, including histamine, into the bloodstream. These chemicals are responsible for causing the symptoms of the allergy.


The majority of food allergies are triggered by specific proteins found in certain foods, such as crustacean shellfish (e.g., shrimp, lobster, and crab), peanuts, tree nuts (like walnuts and pecans), fish, chicken eggs, cow's milk, wheat, and soy. Consuming these foods can lead to the immune system's activation and the subsequent release of allergenic chemicals, leading to various allergic reactions.


What is pollen food allergy syndrome?


Pollen food allergy syndrome, also known as oral allergy syndrome (OAS), is a type of allergic reaction that occurs when someone with a pollen allergy experiences cross-reactivity to certain fruits, vegetables, and nuts. It is important to note that this is not a true food allergy in the traditional sense, as it does not involve the same immune response as typical food allergies triggered by proteins.

People with pollen food allergy syndrome have allergies to certain types of pollens, such as tree, grass, or weed pollens. When they consume certain raw fruits, vegetables, or nuts, their immune system recognizes similar proteins in these foods to the pollen proteins they are allergic to. As a result, their immune system may mount a mild allergic reaction in the mouth, lips, and throat area, leading to various symptoms.

Symptoms of pollen food allergy syndrome typically include:

  • Itching or tingling sensation in the mouth, lips, tongue, and throat

  • Swelling of the lips, tongue, and throat

  • Mild hives or itching around the mouth

  • In rare cases, mild gastrointestinal symptoms like nausea or stomach discomfort may occur

Notably, cooking, heating, or processing the foods involved in OAS can often break down the allergenic proteins, making them safe for consumption. Therefore, individuals with pollen food allergy syndrome may tolerate these foods in cooked or processed forms.

Some common examples of pollen-food cross-reactions include:

  • Birch pollen allergy may cross-react with apples, pears, peaches, and almonds.

  • Grass pollen allergy may cross-react with tomatoes, potatoes, and melons.

  • Ragweed pollen allergy may cross-react with bananas, zucchini, and cucumbers.

If someone experiences symptoms consistent with pollen food allergy syndrome, they should consult an allergist for proper diagnosis and management. In some cases, an allergist may perform skin prick tests or blood tests to identify specific cross-reactive allergies. It's essential to differentiate OAS from true food allergies, as the management and implications can differ significantly.


What is exercise-induced food allergy?


Exercise-induced food allergy, also known as exercise-induced anaphylaxis (EIA), is a rare and potentially severe allergic reaction that occurs when certain foods are consumed in close proximity to exercise or physical activity. In this condition, the combination of specific foods and exercise triggers an allergic response, which can lead to symptoms ranging from mild discomfort to life-threatening anaphylaxis.


The exact mechanism behind exercise-induced food allergy is not fully understood, but it is believed to involve a combination of factors. Physical activity can lead to changes in the body that affect the absorption and metabolism of food proteins, potentially increasing the likelihood of an allergic reaction.


The symptoms of exercise-induced food allergy can include:

  • Skin reactions: Hives, itching, or redness.

  • Respiratory symptoms: Wheezing, difficulty breathing, or asthma-like symptoms.

  • Gastrointestinal issues: Nausea, abdominal pain, or vomiting.

  • Cardiovascular symptoms: Rapid or irregular heartbeat, low blood pressure, or lightheadedness.


In some cases, exercise-induced food allergy can progress rapidly to anaphylaxis, a severe and life-threatening allergic reaction that requires immediate medical attention.

The triggering foods can vary from person to person, but common culprits include wheat, shellfish, nuts, and certain fruits. The specific combination of food and exercise is unique to each individual with this condition.


If someone suspects they may have exercise-induced food allergy, it is crucial to seek medical evaluation from an allergist or immunologist. The diagnosis may involve a combination of physical examination, medical history review, and allergy testing to identify the specific allergens and triggers. Management of this condition typically involves avoiding the triggering food in combination with exercise and being prepared to handle any potential allergic reactions, including carrying emergency medications like epinephrine.


Food intolerance and other reactions


Food intolerance or reactions to other substances consumed can produce similar signs and symptoms as seen in food allergies, such as nausea, vomiting, cramping, and diarrhea.

The degree of food intolerance varies depending on the type, and in some cases, consuming small quantities of problematic foods may not elicit a reaction. On the other hand, true food allergies can be extremely sensitive, with even a minuscule amount of the allergenic food triggering an allergic response.


Diagnosing food intolerance can be challenging because certain individuals may not be sensitive to the food itself but to a specific substance or ingredient used during food preparation. This makes identifying the exact cause of the intolerance more complex.


Conditions that can produce symptoms mistaken for a food allergy encompass:

  1. Insufficient enzymes for food digestion: Some individuals lack adequate enzymes required to fully digest certain foods. For example, insufficient lactase enzyme can lead to lactose intolerance, causing bloating, cramping, diarrhea, and excess gas when consuming milk products.

  2. Food poisoning: Food poisoning can sometimes mimic allergic reactions, especially when caused by bacteria in spoiled fish, such as tuna, which can produce toxins triggering harmful responses.

  3. Sensitivity to food additives: Certain individuals may experience digestive reactions and other symptoms after consuming food additives. For instance, sulfites used in preserving dried fruit, canned goods, and wine can induce asthma attacks in those sensitive to food additives.

  4. Histamine toxicity: Improperly refrigerated fish like tuna or mackerel, containing high bacterial levels, may also harbor elevated histamine levels, leading to symptoms similar to food allergy. This condition is known as histamine toxicity or scombroid poisoning, not a true allergic reaction.

  5. Celiac disease: Often referred to as a gluten allergy, celiac disease is not associated with anaphylaxis. It does, however, involve an immune response, but one that is more complex than a standard food allergy. Celiac disease is a chronic digestive condition triggered by gluten consumption, a protein found in wheat, barley, rye, and related foods. In individuals with celiac disease, eating gluten triggers an immune reaction that damages the surface of the small intestine, leading to difficulties in absorbing certain nutrients.



What is the difference between food allergy and food intolerance?


Food intolerance and food allergy are two distinct conditions, although they can sometimes present similar symptoms. The key difference lies in the underlying mechanisms of the body's response to specific foods.

  • Food Intolerance: Food intolerance occurs when the body has difficulty digesting certain foods or components of foods. It is not an immune system response but rather a digestive issue. The most common types of food intolerance are lactose intolerance (inability to digest lactose, a sugar found in milk) and intolerance to certain food additives like sulfites or MSG.

  • Symptoms of Food Intolerance: Symptoms of food intolerance can vary and may include bloating, gas, abdominal pain, diarrhea, or constipation. These symptoms usually appear gradually and are often related to the amount of the problematic food consumed. Food intolerance reactions are generally less severe than allergic reactions.

  • Food Allergy: Food allergy, on the other hand, is an immune system response triggered by specific proteins in foods. When an individual with a food allergy ingests the allergenic food, their immune system perceives the proteins as harmful invaders and releases chemicals like histamine to defend against them.

  • Symptoms of Food Allergy: Food allergy symptoms can range from mild to severe and may involve skin reactions (hives, itching), respiratory symptoms (wheezing, difficulty breathing), gastrointestinal problems (nausea, vomiting), and in severe cases, anaphylaxis, which is a potentially life-threatening reaction that affects multiple body systems simultaneously.

  • Timing of Reactions: One critical distinction between food intolerance and food allergy is the timing of the reaction. Food intolerance reactions usually occur several hours after consuming the offending food, while food allergy reactions tend to manifest within minutes to an hour after ingestion.

  • Diagnosis and Management: Diagnosing food intolerance often involves identifying problem foods through an elimination diet or specific diagnostic tests. In contrast, diagnosing food allergies typically requires allergy testing, such as skin prick tests or blood tests, to identify the specific allergens triggering the immune response.


**Management of food intolerance may involve limiting or avoiding the problematic foods, whereas food allergies require strict avoidance of the allergenic foods and, in the case of severe allergies, carrying epinephrine auto-injectors for emergency treatment. It's essential to differentiate between food intolerance and food allergy because their management and potential risks can vary significantly. If you suspect you have a food intolerance or food allergy, it is crucial to seek advice from a qualified healthcare professional for proper evaluation, diagnosis, and management.


What are the risk factors of food allergy?


Risk factors for food allergies include:

  1. Family history: If conditions like asthma, eczema, hives, or allergies such as hay fever are common in your family, your risk of developing food allergies is higher.

  2. Other allergies: If you already have an allergy to one type of food, you may have an increased risk of developing allergies to other foods. Similarly, if you have other allergic conditions like hay fever or eczema, your likelihood of having a food allergy is greater.

  3. Age: Food allergies are more prevalent in children, particularly in toddlers and infants. As children grow older, their digestive systems mature, and they become less susceptible to absorbing food or components that trigger allergies. Fortunately, many children outgrow allergies to milk, soy, wheat, and eggs. However, severe allergies and allergies to nuts and shellfish are more likely to persist throughout life.

  4. Asthma: Food allergies and asthma often coexist. When they do, both conditions are more likely to cause severe symptoms.


Factors that may increase the risk of experiencing an anaphylactic reaction include:

  1. Having a history of asthma.

  2. Being a teenager or younger.

  3. Delaying the use of epinephrine to treat food allergy symptoms.

  4. Not having hives or other skin symptoms during the allergic reaction.

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