07 Jun What Is A Food Sensitivity Test?
The pandemic has shifted how many people approach their health, motivating people to address their general wellness like never before. A huge part of that is a healthy diet, with many people taking more mindful approaches to how and what they eat. It has also led people to address food issues they have never fully explored, such as food sensitivities. What is a food sensitivity test and how does it differ from allergy testing? How do food sensitivity tests work? Keep reading to learn more about food sensitivity testing and determine if it’s the right choice for you.
Understanding food sensitivity vs. food allergy
There is much confusion about the difference between food sensitivity and food allergy. Many people may think that food sensitivity is a less severe allergic reaction, but that is incorrect. Food allergies and food sensitivities trigger different body symptoms.
Food allergies occur when your immune symptom attacks a protein in food you have eaten as if it was a foreign invader. It treats the protein the same way invading bacteria, fungus, or viruses would be treated, triggering an immune response that produces antibodies. The physical responses produced are what we recognize as food allergies. Most food allergies are immunoglobulin E (lgE) reactions, meaning they cause immediate chemical reactions, such as the release of histamine.
Symptoms of food allergies include:
- Digestive symptoms like nausea or vomiting
- Skin reactions such as itching, swelling, or hives
- Anaphylaxis, a dangerous reaction including difficulty breathing, dizziness, wheezing, and death
Unlike food sensitivities, food allergies can be fatal. Some people may have particularly severe food allergies in which even a tiny exposure to an allergen can result in anaphylaxis.
90% of food allergies are attributed to eight foods:
- Tree nuts
Non-lgE food allergies occur when other areas of the immune system (aside from lgEs) are triggered by a food. Generally, these types of reactions are less likely to be life threatening and occur in the gastrointestinal tract. Typical symptoms include vomiting, diarrhea, or bloating.
Food sensitivities are sometimes also called food intolerances. More common than food allergies, food sensitivities occur when your body cannot properly break down a food, or your body reacts to a food.
There are a few reasons why you might have a sensitivity or intolerance to a food:
- Lacking enzymes necessary to digest certain foods
- Reactions to additives or preservatives (ie sulfites, artificial colors, or MSG)
- Sensitivity to natural sugars in certain foods (ie broccoli, brussels sprouts, or onions)
- Sensitivity to chemicals (such as caffeine)
Food sensitivities and intolerances are generally less severe than food allergies. Food sensitivity symptoms can vary in types of reaction and typically can take a few hours to a few days to appear.
Food intolerances specifically have digestive-related symptoms such as:
- Bloating and gas
Examples of food intolerances include:
- Gluten sensitivity: Found in wheat, barley, and rye, gluten is a protein that can cause food intolerance symptoms. It should be noted that gluten sensitivity is a different condition than celiac disease, which is an autoimmune response to gluten. Currently, the only way to avoid gluten sensitivity symptoms is to avoid all gluten-containing grains.
- Histamine intolerance: Histamine is found in aged foods like preserved meats, cheeses, or wines. Symptoms of histamine intolerance can vary, including diarrhea, vomiting, stomach pains, or skin rashes. While some people experience relief from symptoms with the aid of an over-the-counter enzyme replacement supplement, others may have to avoid foods containing histamine.
- Lactose intolerance: The body needs a specific enzyme – lactase – to digest lactose, a type of sugar found in dairy. Some people’s small intestines do not produce enough lactase to properly break down dairy products, leading to lactose intolerance. Symptoms may be alleviated with an enzyme replacement supplement (ie, Lactaid.)
What is a food sensitivity test?
Food sensitivity tests are designed to identify food sensitivities you may have. There are several types of food sensitivity tests.
Elimination diet and challenge test
Elimination diet followed by an oral food challenge is considered the gold standard for identifying food sensitivities. To adhere to an elimination diet, your healthcare expert will direct you to stop eating foods to which you may have a sensitivity. Sometimes elimination diets can cause temporary withdrawal symptoms. You should remain on the elimination diet until these reactions clear, which typically takes about two weeks.
Once symptoms are clear, you can begin testing foods in an oral challenge. When choosing foods to eliminate, you should choose foods to which you suspect you have a sensitivity. If you are uncertain about what could be triggering a food sensitivity, you can start with the most common allergen foods, such as dairy, soy, or wheat.
Cell-based blood tests
Cell-based blood tests for food sensitivities have existed since the 1950s. In that time, some tests have been discontinued due to issues with accuracy. Over time, testing has been improved and automated to help make testing more accessible. Drawn blood is exposed to a variety of food components and foods in a lab and then monitored to observe how the blood reacts to the various components.
- Antigen Leukocyte Cellular Antibody Test (ALCAT): This is an older test that measures changes in the size of your white blood cells in reaction to food antigens. This test is less accurate than tests developed more recently which measure changes in solid-to-liquid ratio within white blood cells. In one study, people suffering from Irritable Bowel Syndrome (IBS) experienced a significant reduction in symptoms like bloating and abdominal pain after following an ALCAT-based diet for two weeks.
- Mediator Release Test (MRT): These tests assess changes in the solid-to-liquid ratio of blood in response to a food allergen. White blood cells are the solid that is measured. When exposed to an allergen, white blood cells shrink, which suggests the release of chemicals like histamine and leukotrienes. MRT results are used to create a diet known as LEAP, which stands for Lifestyle Eating And Performance. One 2004 study showed that patients suffering from IBS who followed a LEAP diet saw a notable improvement in symptoms.
There are other tests available to determine food sensitivities, but research supporting their accuracy and usefulness is limited. In some cases, they are not recommended.
Antibody-based blood tests
Antibody blood tests identify food sensitivities by measuring how many immunoglobulin G (lgG) antibodies your body produces in response to certain foods. There is controversy over the efficacy of this test for a few reasons.
Scientists have different stances on what the presences of antibodies mean. Some insist that it is abnormal to have high levels of lgG in response to foods, and that test results are useful. Others who do not support antibody testing say the presence of lgG is a protective response against food allergy reactions in some cases. Some also believe that an antibody response simply indicates an exposure to foods without causing a food sensitivity reaction, meaning that tests can show false positives.
Another concern with lgG antibody tests is that labs often independently develop their own testing techniques and procedures. This can result in varied reproducibility, which means you may not get the same results when analyzing the same sample twice.
If you do get an lgG test, you should make sure your blood sample is analyzed twice for each suspected antigen using side-by-side duplicate testing. This will help ensure test accuracy.
The electrodermal screening food sensitivity test measures the electrical activity of the skin in response to food antigens. Electrical activity is monitored at acupuncture points. A computer with digitized frequencies of individual foods is connected to a brass tube, which is held by the patient in one hand. The patient’s other hand is pressed at a specific point with a probe that is also connected to the computer. The skin’s electrical resistance to digitized food frequencies is generated into a numerical reading which indicates how strong reactions are to each frequency.
Currently, there are no published studies for the effectiveness of this food sensitivity test.
Muscle response test
Muscle response tests are also called applied kinesiology. During the test, patients hold a vial with a food antigen in one hand. The other arm is extended and held parallel to the floor while a practitioner presses on it. Food sensitivities are detected when the arm is easily pushed down. It is unknown if practitioner skill level has a significant impact on test accuracy, but the small number of published studies of this test do not support it as a reliable testing method.
Provocation and neutralization test
The provocation and neutralization test involves injecting food extracts of suspected food allergens under skin. Tests are usually administered on the upper arm, and then subjected to a 10 minute wait period. An area of raised swelling, known as a wheal, indicates a sensitivity to that food.
If a wheal appears, a second injection is administered. The second injection is diluted to be five times weaker than the initial injection, and is designed to neutralize the reaction. After another 10 minute waiting period, if there is no reaction, this is considered your neutralizing dose.
If you react to the second dose, another injection formulated to be progressively weaker is administered. This process is repeated until the neutralizing dose is identified. Once identified, a patient can be taught to self-administer injections on a regular basis to desensitize the body to a food antigen.
This method is not recommended due to the risk of severe allergic reactions during the testing process. Additionally, the number of injections required to complete this test and subsequent desensitizing injections can make it a very slow and painful process.
What is the difference between a food sensitivity test and an allergy test?
Food allergy blood tests detect a different type of antibody and are generally more tailored to the specific allergy. Food sensitivity tests often have large screening panels, meaning they test a wide number of foods and/or food components. Food allergy tests tend to focus more on the suspected allergen(s).
Diagnosing a food allergy requires a more thorough testing process, and may include more than just a blood test. A doctor may also obtain:
- A full medical history, including family history of allergies
- Physical exam
- Skin prick testing
- Oral food challenge (conducted in a medical environment with resources to treat any serious reaction that may occur)
How reliable is food sensitivity testing?
Food sensitivity testing can be a reliable way to detect food sensitivities, however there are many ways in which they can be misused or misinterpreted. This is why getting food sensitivity testing through a medical professional is your best option, as they can ensure test quality and help interpret results.
Results from food sensitivity tests can be confusing. Sometimes the format is broken down into categories of foods and offers lists of what foods may cause a sensitivity. For example, various cheeses may appear in the dairy category. However, this does not give a person the information necessary to accurately navigate their food sensitivity. Food sensitivities can vary in severity, and the amount of allergen in foods can vary greatly. While lists of foods containing food-component allergens may be helpful to someone newly diagnosed with a food sensitivity, it’s important to understand the allergen itself and learn how to determine whether or not a food should be avoided.
This problem is especially prevalent for food sensitivity testing kits, which became popular as a result of the pandemic. While these tests may help identify a food sensitivity, you should follow up with a healthcare expert to get further professional testing and guidance. Tests can vary in quality and may be affected by environmental factors during shipping and storage. Home testing kits also may present an opportunity for user error, further affecting the accuracy of the test.
A doctor may conduct additional testing beyond a blood test to verify a food sensitivity. Additional testing might take the form of more blood tests, hair analysis, or electrodermal testing.
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