IgE Mediated Food Allergies
A food allergy is any adverse food reaction that is caused by an immunological response. In contrast, a food intolerance is any adverse reaction due to a nonimmunologic mechanism. Examples of food intolerances include:
- Pharmacologic properties of the food (i.e. simple sugars causing hyperactivity in children).
- Toxins in the food (i.e scromboid fish poisoning)
- Foods that exacerbate gastroesophageal reflux (acidic or spicy foods).
- Metabolic disorders (i.e Lactose intolerance)
- Autoimmune condition triggered by exposure to gluten (Celiac Disease).
Although almost any food can lead to an allergic reaction, the most common food allergens include: cow's milk, egg, wheat, soy, peanut, tree nuts, fish, and shellfish.
Food allergies can cause either immediate or chronic symptoms. Immediate symptoms include hives, swelling, vomiting, difficulty breathing, throat tightness, or anaphylaxis. Anaphylaxis is a severe, potentially life-threatening allergic reaction. Chronic symptoms associated with food allergies can include gastrointestinal symptoms (i.e abdominal pain, diarrhea), Failure to thrive in children, and Atopic Dermatitis (eczema).
The patient's history is one of the key aspects in making the diagnosis of a food allergy. It is important to get a history of prior reactions to foods, but also to obtain your past medical history and family history to assess for risk factors for food allergies. In addition to your history, we will perform testing to assess for possible food allergy. Testing can include skin prick testing and/or laboratory testing to specific foods. Food challenges are performed at Weiss Medical either as part of the workup of a food allergy or to assess if an individual has outgrown a food allergy. Food challenges are performed under close observation by one of our doctors.
The only treatment for food allergies is avoidance. If you are diagnosed with a food allergy it is important to carefully read food labels. Specific information regarding how to read food labels is available at www.foodallergy.org.
Once a patient is diagnosed with a food allergy, we will review a food allergy and action plan. Correct dosing of diphenhydramine will be reviewed. The patient will be prescribed an epinephrine auto-injector (EpiPen or Auvi-Q) and we will review appropriate technique. Epinephrine auto-injectors are used to treat anaphylaxis which is a potentially life threatening event.
Oral Allergy Syndrome (Pollen-Food Syndrome)
This is a specific type of food allergy. The reaction is characterized by symptoms that are generally limited to the oral cavity and include: itchy mouth, itchy throat, itchy tongue, or swelling of the mouth, lips, or tongue. Oral allergy syndrome can progress to a severe allergic reaction, but this is very uncommon. This type of reaction occurs to the heat and acid labile proteins found in certain fresh fruits and vegetables. These delicate proteins are denatured (broken down) by heat and acid, and therefore if cooked or processed, patients will not react. This also explains why the reaction does not progress beyond oral symptoms, because as soon as the food reaches the acid in the stomach, it again is denatured (or broken down). The proteins that lead to Oral Allergy Syndrome are known to cross react to certain pollens. Examples of pollens and a few of their cross reacting foods are listed below:
- Birch pollen: apple, peach, plum, pear, cherry, carrot
- Ragweed pollen: melons and banana
- Mugwort pollen (weed): carrot, broccoli, and celery
- Orchard pollen (grass): melon, tomato, white potato
Eosinophilic Gastrointestinal Disorders
Eosinophilic Esophagitis (EoE) is one of the more common type of eosinophilic gastrointestinal disorder. It is a chronic inflammatory condition of the esophagus that is characterized by the presence of increased eosinophils in the lining of the esophagus. Eosinophils are allergy cells that release inflammatory chemicals that can lead to irritation or damage to the esophagus and interfere with its function. Symptoms of EoE include failure to thrive in children, reflux, difficulty swallowing, and even food impaction (food getting stuck in the esophagus). The diagnosis of EoE can only be made via biopsy on endoscopy. However, given food allergies typically cause EoE, appropriate food allergy testing is essential in the evaluation.
Food allergies can also be a trigger for atopic dermatitis. This is most common in young children. One in three children under the age of two years-old with eczema have an underlying food allergy. Please refer to the section titled "Allergic Skin Conditions for a detailed description of Atopic Dermatitis.
Food Protein-Induced Enterocolitis Syndrome (FPIES)
This is condition, which is not a food allergy but rather a food intolerance. It consists of severe vomiting and diarrhea within 2-3 hours of eating the suspected food trigger. This can lead to severe dehydration, and often results in emergency room treatment. This diagnosis is most common in infants, and cow's milk and soy are the most common triggers. Other foods can lead to FPIES and some examples include oat, barley, wheat and potato.