Food Allergy Testing

What people mean when they say food allergies can include a broad range of food reactions.  Some people will say food allergy when referring to lactose intolerance and others mean anaphylactic type food allergies.  In the conventional medical community, food allergy or true allergy refers to food reactions mediated by IgE type antibodies, part of our immune system.  I include any immune mediated reaction in a discussion around food allergies and include those mediated by any antibodies, such as IgA, IgE and IgG. So your gastroenterologist might talk about food sensitivities while I’m talking about food allergies, but we are usually talking about the same thing. I use the terms somewhat interchangeably.

IgA is the type of antibody implicated in celiac disease and can relate to to other food allergies as well.  IgG typically results in delayed type immune based food reactions and are the most common tested in my office.  IgE antibodies have typically been those that resulted in immediate reactions and often anaphylaxis.  However, with increased testing of IgE antibodies to food, we’re finding that the presence of IgE antibodies to foods may not always behave that way and that for some, IgE can result in delayed type responses as well.

How Do I Test for Food Allergies?

At my office, I utilize a blood test to check for food allergies.  I can test for IgA, IgG or IgE, but I typically test IgG. Which test is appropriate for you depends on your regular diet and the types and timing of your allergic symptoms. If you’ve already been avoiding certain foods, we may recommend a diet containing potentially allergenic foods to prepare you for the testing.   There are also specific panels for people who follow different diets and panels to check for cross reactivity.  Other testing methods include the scratch test which is familiar to most people, but I do not offer this test.

Most Common Food Allergies

There are 8 foods commonly identified as the top food allergens, which include:

  • Wheat
  • Soy
  • Tree nuts
  • Peanuts
  • Dairy
  • Eggs
  • Shellfish
  • Fish

We very commonly identify egg and dairy allergies in our testing, but we also note reactions to other foods.  Another benefit of testing is that for non-IgE immune mediated food sensitivities (IgG food allergies), we can retest to check for changes in your levels of reactivity.

What Symptoms Do Food Allergies Cause?

Food allergies can result in a variety of symptoms.  Digestive symptoms are a common complaint, including heartburn, gas, bloating, diarrhea or loose stools, constipation, abdominal pain or cramping and bad breath.  Food allergies may also contribute to worsening respiratory symptoms such as hay fever, sinusitis, cough and asthma.  Skin conditions such as hives and eczema can present.  Pain conditions are often affected by food allergies – you may want to consider food allergy testing if you suffer from fibromyalgia, chronic pain, headaches, migraines or arthritis.  In general, food allergies, because we are exposed multiple times daily, can affect many conditions.

How Can Food Allergies Cause So Many Different Symptoms?

When the body is exposed to food allergens, inflammation develops in the intestines.  If the person eats that food only occasionally, the inflammation diminishes between episodes and they may only notice symptoms on the occasions when they eat that food.   If the person eats that food repeatedly, however, the inflammation can become more chronic.  With chronic inflammation of the intestines, the cells that line the intestine become swollen and puffy.  When the cells are swollen, the tight junctions between cells may become compromised creating gaps between the cells.  This condition is known as “leaky gut.”

 These cells which line the intestine  usually pick and choose exactly which nutrients are absorbed into the bloodstream and act as a barrier to larger particles and substances we don’t want to absorb.  When leaky gut develops, more of these particles may passively diffuse into the blood stream.  The immune system then responds to these foreign particles which would normally not be absorbed – and how does the immune system respond?  By creating antibodies to these foreign substances and releasing inflammatory mediators.  The immune system tries to clear the “infection” or invasion of these substances and mounts increasingly stronger responses when its efforts are in vain.  These inflammatory mediators are not typically specific in their location of action, so if one suffers arthritis or asthma, these vulnerable systems are affected by the increased inflammation and symptoms result or worsen.

Read that through a couple times to make sure you understand that.  It’s an important concept to grasp – that food allergies increase the total body inflammatory burden.  This is how food allergies may contribute to myriad different conditions and body systems.  And this is why when one has a complex condition or suffers from an un-named condition despite lots of testing, we will often consider food allergy testing.  It’s not a shot in the dark, but an effort to address one cause of inflammation that you have control over.

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