What Are Food Allergies?
Food allergies are immune system responses to proteins in certain foods. They involve the production of antibodies, while intolerances cause irritation and sensitivities promote inflammation. It’s estimated that roughly 4% of American adults and 8% of children experience food allergies. Foods that most commonly trigger allergies include:
- Wheat.
- Cow dairy.
- Soy.
- Peanuts and tree-nuts such as walnuts, almonds or pecans.
- Shellfish such as crab, lobster or shrimp.
- Chicken eggs.
- Fish.
Let's take a look at common symptoms, and how to test for food allergies so you can seek proper treatment.
What Are Common Symptoms of Food Allergies?
Symptoms of food allergies can vary and can include the following:
- Itching, rash, eczema or hives.
- Fainting, dizziness or lightheadedness.
- Itching and/or tingling in the mouth.
- Nausea, vomiting, belly pain or diarrhea.
- Swelling of the face, lips, throat, tongue or other body parts.
- Trouble breathing.
- Wheezing or congestion.
You should see your doctor if you experience these symptoms shortly after eating. Anaphylaxis is an acute allergic reaction that can be fatal and requires emergency treatment. Contact emergency services immediately if you experience the following:
- Rapid pulse.
- A severe drop in blood pressure leading to shock.
- Constriction/narrowing of the airway.
How to Test for Food Allergies
If you have any of the above symptoms after eating, it is worth talking to your doctor about one of the following food allergy tests to get to the root of your issues so you can start feeling better. Sometimes it can be hard to determine on your own which food is causing your reaction, especially if the symptoms don’t arise until several hours after eating. That’s where a trained allergist can help you decide which test to use.
1. Skin Tests
Allergy skin tests involve pricking the skin with a small, sterile needle. Either the skin of the forearm or back has a small amount of the food to be tested placed on it or it is placed directly on the needle before pricking the skin. The test results are positive if the skin prick results in a raised bump, called a wheal.
These allergy tests take about 15 to 30 minutes to complete and are not overly painful, though if you receive a positive response it can be itchy, much like a mosquito bite.
2. Blood Tests
Another way to test for food allergies is through a blood test. While these tests are not typically as sensitive or accurate as a skin test, they can be helpful in measuring the amount of immunoglobulin E (IgE), a type of antibody, your body produces in response to a particular food. You will typically receive your results in about two weeks and you and your allergist can discuss them in more detail. They may decide that further testing is necessary and recommend an elimination diet or oral food challenge.
3. Elimination Diet
Another way your allergist might test for food allergies is through an elimination diet. After asking questions in your intake regarding your diet, family history, symptoms and frequency of reactions, they might place you on a special diet that eliminates foods they may suspect are causing your issues or that eliminates the most common food allergens.
They will have you follow this diet for a couple of weeks and keep a journal that includes what you eat and whether you experience symptoms. Eventually they will have you reintroduce these foods to see if they cause a reaction. However, it can be hard to differentiate between whether you are experiencing a true food allergy or a sensitivity or intolerance. The only surefire way to then confirm your food allergy is through an oral food challenge, outlined below.
4. Oral Food Challenge
Oral food challenges are considered the gold standard when it comes to diagnosing food allergies. Once your doctor has helped you narrow down specific foods that are likely causing your allergic reaction they will bring you to their office and feed you increasing amounts of the suspected allergen, noting any reactions.
This process can be dangerous and requires that staff and emergency medications and interventions be on hand at all times. It can also be quite time consuming and costly, so it isn’t always used to confirm a suspected allergy. For some people this solid confirmation of their allergy can be helpful in terms of sticking to a diet that eliminates it moving forward, which can make this test highly useful. If you don’t react to the suspected foods, then it may be safe to include them in your diet once again.
No matter which route you choose, it is best if done with the support of your primary care provider or another qualified healthcare practitioner. If you do discover a food allergy, working with a dietician can help ensure you are not missing out on any key nutrients and provide you with guidance on delicious and nutritious alternatives.