Can Blood Tests Accurately Predict Food Allergies?

A few years ago, I was diagnosed with Grave’s Disease (hyperthyroidism); the toll it was taking on my health was pretty dramatic. I went from an energetic, outgoing, outdoors all the time girl to someone that was lethargic and tired from a constantly racing heart. I choose to see a naturopathic to treat the condition, after a scary  initial consultation with a traditional doctor that included the phase, “radiate your thyroid.” Being a believer in holistic health and medicine, I knew that the naturopath was the way to go.

As part of my treatment, the doctor I worked with prescribed traditional medications to help regulate my T3 levels, but she also had me start a series of herbs, the nastiest tasting tea in the world, and vitamins. Along with that, she also suggested we do allergy testing to see what foods could be triggering inflammation within my immune system. I laid down on the table, let her prick my finger and off my blood went for testing.

When the results came back, they confirmed that I was severely lactose intolerant (not a surprise, I have been since I was young), had moderate intolerances to gluten (again I suspected this) but the results also showed that I was highly reactive to almonds, avocados and eggs (something that had been my morning breakfast for five years). Along with the highly reactive sensitivities, also came lesser ones, including bananas, pineapple, corn, cabbage, peanuts, and a few other things that made eating the greatest challenge in the world (and I am already a very healthy eater).

So What Do You Do When The Foods You Love To Eat Are “Taken” Away From You?

With the results from my testing, I proceeded to take everything out of my diet that was on that list. No bananas, no avocados, no pineapples, no corn! With the change, my cooking became more creative, I prepared the majority of meals at home since I couldn’t safely eat out and I became a master of very costly “allergen free” cooking. After a while, though cooking is still a passion of mine, I became tired of always worrying about food allergies and/or intolerances. Sometimes, you just want to venture out to your favorite restaurant and eat whatever appeals to you. Because of this, I decided to investigate the allergy tests I was given because aside from dairy (lactose) and corn, I didn’t think my allergies or intolerances were as severe as what was being reported.

What Are Food Allergies?

Before you believe you’re allergic to something, I think you should understand what a food allergy actually is. According to the Mayo Clinic, a food allergy is a reaction that occurs in your immune system after you’ve eaten a certain food. These foods can lead you to break into hives, develop itchiness or swelling in the throat, nose, mouth and airways or even lead to anaphylaxis (yes, food allergies can be life threatening).  When it comes to a food allergy, almost 90 percent of all food allergies are related to eight foods: milk, soy, egg, wheat, peanut, tree nuts, fish, and shellfish.

What’s The Difference Between A Food Allergy and A Sensitivity (or Intolerance)?

According to the American Academy of Allergy, Asthma, and Immunology, a food allergy is a reaction to food proteins that you system can’t break down and results in severe reactions like the ones listed above. A food intolerance (also known as sensitivity) is related to an enzyme deficiency in your digestive tract that makes it hard to process a certain food, but it doesn’t lead to the severe outcomes that an allergy does. We can be sensitive to foods, but not allergic to them.

How Do You Know If You Have Food Allergies?

There are a variety of ways to determine whether or not someone has food allergies or intolerances, including simple elimination diets, saliva, hair, skin and/or blood tests. Two types of blood tests, IgE and IgG, are becoming more common for determining allergies as they are believed to provide the greater accuracy in finding food allergies and sensitivities. IgE test can only be ordered by licensed health care providers, while others (usually IgG) can be ordered online and sent directly to your home and some you can only get from holistic practitioners.

Two Types of Blood Tests – IgE and IgG

When it comes to IgE and the IgG tests, there’s often a lot of confusion between the two. With the IgE test, a clinician is measuring the immune system’s response to particular foods by measuring the allergy-related antibody known as immunoglobulin E (IgE), an antibody that attacks foreign proteins that produce an immediate allergic response. The antibodies travel to cells, causing allergic reactions in the skin, gastrointestinal tract and/or anaphylaxis.  

With the IgG test, a clinician is measuring Immunoglobulin G (IgG) antibodies, IgG antibodies are used to detect (predicting and/or serving as indicator) possible sensitivities or intolerances someone may have towards certain foods; they do not measure or produce immediate allergic responses.

According to the Food Allergy Institute, IgE antibodies occur in abnormally large quantities in people with allergies; IgE antibodies are the only true indicator of food allergies. On the other hand, IgG antibodies can be found in people that have food allergies, but also in the general world population. Experts believe that the production of IgG antibodies is a normal response to the food you’re eating on a regular basis.

Should You Get An IgG or an IgE Test To Determine Food Allergies?

If you think you have food allergies and something as simple as an elimination diet hasn’t helped you determine if something in your food may be causing issues, then see you doctor and have them refer you to allergist for IgE testing. There’s a lot of controversy surrounding, IgG testing and most doctors in the believe that IgG testing is unreliable and that the results lack clinical utility. In an interview with Vice Magazine, Robert Hamilton, a professor of medicine at Johns Hopkins University said:

There is no firm, peer reviewed data that verifies that IgG antibody is diagnostically useful. This type of food sensitivity test is essentially a bogus test. It doesn’t mean that you are sensitive or intolerant to certain foods, and it doesn’t mean you should avoid exposure to them, or avoid eating them.

The science behind the validity and reliability of IgG tests is solid, given the fact that results are based on “predictive” indicators, it makes it hard for them to be a credible tool for making changes in your diet eliminating foods. So if you think you’re allergic to foods, get an IgE test.

If You’re Not Allergic To It, Then You Can Probably Eat It

After personally having both the tests done and changing my food choices based on the results, I believe unless it’s proven you’re allergic to it (IgE), then you can probably eat it. My IgG tests indicated a large amount of food sensitivities, but if I look at what I was eating regularly at that time, most of those foods were staples in my diet. In the last two months, I’ve reintroduced foods that the IgG test indicated I had problems with back into my diet, eating them once or twice a month. To be perfectly honest, I haven’t had noticeable effect with the exception of gluten, so I’m leaving it out. And after three years of not having pineapples, bananas and avocados (and even cabbage!), I’m glad I’m adding them back!

In a society so caught up in “eating clean” and eating well, we are starting to suffer from too much deprivation simply because one study or doctor eludes to something that could cause problems with our health. But think about it, why would you deprive yourself of nutrient dense, whole foods if you aren’t severely allergic to them? An avocado isn’t fast food.  If you’re not allergic or intolerant of it, then eat it (or eat it in moderation). Tamara Duker Freuman, M.S., R.D., C.D.N., makes a stellar point when she said, “People can’t keep up restrictive diets regardless of how they feel.” Personally, I’m happy to have avocado for guacamole and pineapple in my smoothies — and no more avoiding real food that plays a key role in my already healthy diet that I haven’t been irrevocably proven I’m allergic to (I do mourn not being able to eat cheese daily).

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