Food Allergy Testing
Hypersensitivity to food
Food hypersensitivity refers to both food intolerances and food allergies, which are not the same thing. Intolerance symptoms are generally less serious and often limited to digestive problems. Allergy testing can help sort out whether you have a food allergy or a food intolerance.
A true food allergy causes an immune system reaction that affects numerous organs in the body. It can cause a range of symptoms. In some cases, an allergic food reaction can be severe or life-threatening.
Food intolerances can result if your body lacks the enzymes or chemicals needed to digest a food. Your body may be unable to absorb nutrients, or it may react to naturally occurring chemicals in food.
Common food intolerances include
- lactose intolerance and hereditary fructose intolerance (lack of particular enzymes)
- celiac disease (caused by an immune response to gluten protein)
- sensitivity to salicylate (natural chemicals in apples, citrus fruits, strawberries, tomatoes, and wine)
- sensitivity to amine (natural chemicals occurring in chocolate, cheese, bananas, avocado, tomato or wine).
A food intolerance can be harder to diagnose than a food allergy. First of all, you need to avoid food with additives during testing.
We may use an elimination diet to isolate problem foods and chemicals.
First, you will remove suspect foods from your diet and add them back, one at a time. You can keep a diary to note any reactions to food as you add them back.
Last, you will once again stop eating the problem foods, one at a time. The list should be smaller this time. The goal is to see if the symptoms clear up for good.
If your symptoms have not subsided after six weeks, then food intolerance is unlikely.
Food allergy is an abnormal immune response to food.
When immunoglobulin (IgE), an antibody, binds to food molecules, a protein in the food is usually the problem. The antibody triggers the release of chemicals like histamine in allergic and inflammatory reactions.
Symptoms and signs of food allergies usually show up soon after exposure, within minutes or hours. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure.
Anaphylaxis is a severe allergic reaction to a toxin or foreign substance the body has become hypersensitive to.
Food allergy testing
The first step in allergy testing is a thorough medical history. The doctor will ask questions to help decide whether a food allergy is causing your symptoms. She will then perform a physical exam.
Several proven diagnostic methods for food allergy are:
- Skin prick test only works for IgE antibodies
- Patch testing for delayed food reactions tries to learn if a specific substance causes allergic reddening and swelling of the skin
- Blood test only detects IgE allergens
- Oral food challenge must be done in a hospital, due to the possibility of anaphylaxis
Depending on your medical history and initial test results, you may have more than one test before your diagnosis.
Treatment for food allergy
- A systemic reaction, anaphylaxis, is very serious. It usually requires an immediate dose of epinephrine (EpiPen), then transport to an emergency room for further treatment.
- Steroids can calm down immune system cells. They should not be used to treat anaphylaxis, because steroids take too long to reduce inflammation.
- Antihistamines can block the action of histamine. Histamine causes blood vessels to dilate and leak plasma proteins. It also causes itchiness by affecting sensory nerves.
- Treatment, finally, is total avoidance of the foods identified as allergens. This means never eating, touching, or inhaling the problem food.
Do you think you have a food intolerance or a food allergy? Come in for a consult to discuss your experiences.
More about food sensitivities
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