Following the low FODMAP diet can be a huge pain in the butt. So, you may be wondering can food sensitivity tests identify IBS triggers? In this article, we'll talk about what food sensitivity tests do, how they work, and if they can help you find your dietary triggers.
What's the Difference Between an Allergy and an Intolerance?
First of all, people with IBS can refer to people having food allergies or food intolerances/”sensitivities.” So, what's the difference?
A food allergy is when your immune system reacts to the proteins in everyday food as if it were something that might harm you. According to current research, true IgE-mediated food allergies affect 3.5-4% of the population.
Allergy symptoms may include itching, hives, trouble breathing, tingling or swelling in the lips or mouth, abdominal pain, nausea, vomiting, or diarrhea.
A food intolerance (or “sensitivity”) happens when foods that should be broken down and absorbed by the body continue to travel through the digestive stem, unabsorbed. As they travel, they may pull water into the bowel and be fermented by gut bacteria. This may lead to painful cramping, bloating, constipation, or diarrhea.
Unlike allergies, reactions caused by an intolerance will resolve as soon as the trigger has exited the digestive system.
How Are Allergies Diagnosed?
If you or your healthcare team suspect a food allergy may be the culprit behind your symptoms, the first thing your doctor should do is review your medical history. If they find evidence that an allergy is likely, they may send you for a skin prick/scratch test or a serologic study to test for allergies. So, what do these tests do?
When your body encounters a protein it doesn't recognize, it may identify the protein as a threat (damn you pollen!). If your body meets the protein again, it will release a set of antibodies called Immunoglobulin E (IgE). These antibodies are like tattletales that attach to specialized cells in your body. They are called “mast cells” and white blood cells in the bloodstream called “basophil.” Once activated, the mast cells and basophils will begin to release histamine and other inflammatory chemicals. This creates an allergic reaction that starts where you were first exposed (like your mouth, your lungs, or your digestive tract).
In a skin prick/scratch test, a tiny puncture is made in the skin, and a concentrated dose of the allergen is applied directly to the wound. This introduces the allergen directly to your bloodstream. If you do have an allergy, your body will produce a “wheal” around the contact site as your body releases histamine to combat the proteins.
In a serologic study, the presence of specific IgE antibodies is tested in a small sample of blood taken.
While both of these tests can help determine if you have a true allergy, a medically supervised “oral food challenge” is the gold standard in testing for food allergies.
To complete an oral food challenge, you eat the test food in increasing amounts while in a medically supervised environment. The medically supervised environment is key here, friends! So, please don't try this one at home.
What Are Food Sensitivity Tests?
Commercial food sensitivity tests models after an IgE serologic test. But, instead of looking for the antibody IgE, they look for an antibody called Immunoglobulin G (IgG).
You complete the test by sending a blood or hair sample to a lab or using an at-home finger-prick test to collect a blood sample.
Testing kits typically cost between $300 – $700 and usually test somewhere between 90-100 foods. The tests are available online and through many naturopathic clinics in North America.
The Problem with Sensitivity Tests
There are a few things we need to talk about here. First, research shows that our bodies produce the antibody IgG, whether or not we react to them, every time we are exposed to specific proteins. So, while an IgG test can show you what you've eaten recently, it can't necessarily determine if you're sensitive to that food.
Second, research is starting to show that IgG may actually indicate tolerance to foods, not intolerance. Several studies have shown that as individuals become more tolerant of foods they were allergic to, their levels of IgE decrease, and their levels of IgG increase. This may explain why IgG levels are often higher in foods we eat regularly – like dairy, wheat, and eggs.
Third, there is no scientific body that supports IgG and other food sensitivity tests. In 2012, the scientific community's concern over the use of food sensitivity tests compelled Stuart Carr of the Canadian Society of Allergy and Clinical Immunology (CSACI) to release an official position statement on IgG testing.
In his statement, he stressed that no body of research currently supports IgG testing for the use of predicting food sensitivities. His position is supported by both the American Academy f Allergy Asthma and Immunology and the European Academy of Allergy and Clinical Immunology.
He also confirmed that current research suggests the presence of IgG in a specific food is a marker of exposure and tolerance to that food. Therefore, positive test results for food-specific IgG would be expected in normal, healthy individuals.
Finally, and most importantly, since IgG levels are often the opposite of IgE levels, based on a food sensitivity report, a person with a true allergy may inadvertently add back food they're allergic to with life-threatening consequences (e.g. lactose intolerance or allergy to tree nuts).
Food Sensitivity Tests and IBS
Food sensitivity tests pose a unique problem for people with IBS. As many people have already cut out large groups of foods, fast before leaving the house or eat as little as possible to avoid triggering their symptoms.
People with IBS will likely find many of their “safe foods” listed as food sensitivities because food sensitivity tests report higher levels of IgG in the foods we eat regularly.
Aside from the emotional upheaval of feeling like no food is safe to eat, food sensitivity tests may lead people with IBS to further restrict their diets without any real benefit to their health. This can lead to nutrient deficiencies and malnutrition, as well as lowering the overall quality of life for people with IBS.
If you need help finding your IBS food triggers, the low FODMAP diet is a short-term program designed to help people with IBS test several common dietary triggers. Research has shown the program helps 3 out of 4 people with IBS reduce their symptoms by up to 75%, so it's worth investigating further.
Can Food Sensitivity Tests Identify IBS Triggers? Final Thoughts
While food sensitivity tests claim they can help you identify over 100 food sensitivities, research has shown that, currently, they can't deliver on that promise. So, can food sensitivity tests identify IBS triggers? As of right now, no. If you need help finding your dietary triggers, save your money and try an elimination diet/re-challenge test (like the low FODMAP program) with your healthcare team.
You might also like one of these:
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