How to recognize food allergies
By Marie Spano, RD
How do food allergies develop and why?
Food allergies develop when the body mistakes a specific food as a threat. Initial exposure to the food will produce no symptoms though your body will make an immunoglobulin (IgE) antibody to the allergen. Upon subsequent exposure to the food allergen, the IgE antibody binds with the food causing an allergic reaction and the release of chemicals including histamine.
Though the exact cause of food allergies is unknown, individuals with a family history of food allergies, asthma or eczema have a greater risk of developing a food allergy.
Exercise-induced food allergy occurs after a person eats a specific food and then exercises. As the body temperature rises during exercise, allergy symptoms develop. Foods that are commonly associated with this type of reaction include crustacean shellfish, alcohol, tomatoes, cheese and celery. Treatment involves avoiding food for a few hours prior to exercising.
Oral allergy syndrome is the most common food allergy in adults yet it isn’t a direct food allergy. People with oral allergy syndrome are allergic to specific tree and weed pollens and therefore fruits and vegetables that have remnants of the tree or weed pollen found in them. Symptoms appear soon after consuming the fruit or vegetable and are typically localized to the mouth and throat. Cooking the fruits or vegetables should prevent an allergic reaction.
Allergic reactions to food range from mild to severe:
- Itching or swelling in the mouth
- Face, tongue or lip swelling
- Coughing or wheezing
- Dizziness or lightheadedness
- Flushed skin or rash
- Gastrointestinal symptoms such as vomiting, diarrhea, abdominal cramps and pains
- Hives or eczema
- Trouble breathing
- A decrease in blood pressure
- Anaphylaxis (which can be life-threatening)
Top 8 Allergenic Foods
Over 160 foods cause allergic reactions, but the Food Allergen Labeling and Consumer Protection Act (FALCA) has identified the eight most common allergenic foods:
- fish (bass, flounder, cod etc.)
- crustacean shellfish (crab, lobster, shrimp etc.)
- tree nuts (almonds, walnuts, pecans)
- soybeans (which account for approximately 90% of food allergic reactions).
Though the FALCA requires every food product with two or more ingredients to list the ingredients in descending order by predominance, companies are not required to indicate the potential for cross-contact with allergenic foods. For instance, shared equipment or processing lines and even environmental factors may lead to trace amounts of an allergenic food incorporated into a food not intended to contain the allergen. An oat crop planted closely to a wheat crop may contain trace amounts of wheat due to wind. And, a chocolate chip cookie produced on equipment that produces peanut butter cookies may contain trace amounts of peanuts. When a company cannot control for the potential presence of certain ingredients, the company can use statements such as “produced in a plant that uses peanuts” to indicate when a food product may contain a major allergen or is produced in a facility that also produces foods containing any of the eight major allergens.
Food Allergy Diagnosis and Treatment
Diagnosis of a food allergy starts with a thorough medical history including symptoms, food intake and allergy medicines. Also, a diet diary and symptom diary may provide helpful details.
Additionally, skin prick tests and blood tests may be used to identify food allergens. However, a person can have a positive skin prick or blood test without being allergic to the food and therefore, physicians often use both a detailed food history and test results to make a diagnosis and possibly an elimination diet and food challenge develop a treatment plan.
The only proven treatment of food allergies is strict avoidance of the allergen. If exposed, an antihistamine may help if the reaction is localized. Also, anyone who experiences a food allergy should carry injectable epinephrine with them at all times. In addition to avoiding the food allergen, it is important to avoid ingredients made from the food and possibly even foods that may be cross-contaminated. Though companies are required to list the ingredients in their products by their common names, some ingredient names may be unfamiliar or confusing to consumers making it difficult to detect if the food contains an allergen. Also, spices, flavorings, and certain colorings are declared as a class and exempt from labeling requirements.
Proper diagnosis is the most critical step to managing food allergies. And though sometimes mistaken for an allergy, a food intolerance is a reaction to a food that doesn’t involve an IgE-mediated immune response. For more information about food intolerances, click here.
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