By Megan Pennington (bio below)
If you think food is to blame for your eczema, asthma, tummy troubles or other health condition, an elimination diet is a good place to start. But if this does not appeal to you or if you were not successful in eliminating you or your child’s symptoms with this type of diet, there is another way.
Several tests are available which can help you identify the precise foods (and chemicals) causing an immune reaction in your body.
First, know how to identify the type of adverse food reaction you’re having by reading last week’s post: Adverse Food Reactions Explained: Symptoms of Food Allergy vs. Sensitivity vs. Intolerance.
Here are the most common tests and their distinguishing features:
Types of Allergy Testing
Allergy Skin Test
Also called an Allergy Scratch Test or Skin Allergy Test, this test involves exposure of an antigen (food component or chemical) to mast cells in the skin. Since type 1 hypersensitivities (allergies) cause the release of histamine from mast cells, this test is useful for identifying moderate to severe type 1 reactions. It is less helpful in identifying mild reactions, and unfortunately has not shown high accuracy in identifying food allergies. An allergy skin test is not useful in identifying food sensitivities or intolerances, as these do not involved the mast cells (wrong pathway).
IgE Allergy Blood Tests
This test quantifies IgE antibody response using a blood test. IgE is what triggers mast cells to release histamine. An allergy blood test is only useful for identifying IgE mediated reactions (type 1/allergies), but not food sensitivities or intolerances. They are more accurate than a skin test for identifying food allergies.
Histamine Release Test (HRT)
This type of test quantifies the level of histamine released using a blood test. This is useful in identifying type 1 reactions (allergies), but not food sensitivities or intolerances. These tests have shown the same accuracy as IgE tests (above), but are not commonly used because the sample is less stable.
Types of Food Sensitivity Testing
IgG Blood Test (by ELISA)
An IgG test quantifies an IgG antibody response using a blood test. This is useful for identifying reactions involving IgG, however does not identify reactions involving IgM, compliment, or direct cell to cell contact. Not useful in identifying type 1/allergies or food intolerances.
In addition, IgG has been shown to play a role in immune tolerance as well, so it is not clear whether high levels of IgG after the exposure to a food is indicative of an immune reaction or an immune tolerance.
Learn more about IGE vs IGG testing.
Lymphocyte Response Assay (by ELISA/ACT)
Also known as LRA, this is a blood test that measures the color change in lymphocytes (a type of white blood cell) after exposure to an antigen. It can test many different antigens and has good marketing claims, however there are no published studies regarding its reliability or validity at the time of this writing. This test does not consider the importance of mediator release during the immune response to a food antigen, which is a disadvantage, considering that mediators are what cause the symptoms we want to ultimately avoid. Does not identify food allergies or intolerance.
This is a blood test which measures the change in white blood cell size after exposure to an antigen, which is an indirect measurement of mediator release (those immune chemicals we talked about earlier, that lead to symptoms). The ALCAT test showed an 83% correlation with double-blind oral challenge (this is good). It is useful in identifying most food sensitivity reactions, however not those involving lymphocytes due to their small size. Does not identify food allergies or intolerance.
Mediator Release Test
Also known as MRT, this is a blood test designed by the same scientist as ALCAT listed above. Mediator Release Test uses newer technology, measuring the change in ratio of liquid to solids after blood exposure to an antigen. This change in volume shows the quantity of mediators released, which indicates the severity of the immune reaction and does not exclude any of the various immune pathways involved. This test shows excellent accuracy (94.5% sensitivity and 91.7% specificity) and reliability (>90%) in clinical study. Helpful in identifying all non-IgE mediated immune reactions. Can be combined with LEAP (Lifestyle Eating and Performance) protocol and elimination diet to help identify other adverse reactions, such as food intolerances and allergies.
There are other companies/tests which have not been mentioned here that claim to identify food allergies, sensitivities, and intolerances. For the purposes of this article, I have focused on the most reputable and reliable, relating primarily to food allergies and sensitivities. Food intolerances and other digestive issues are a different topic completely, and thus have not been adequately discussed here.
** A note about Celiac Disease** Please be aware that none of these tests can be used to identify Celiac Disease, as this diagnosis requires an endoscopy with a duodenal biopsy of the intestinal villi. A mediator release test such as MRT may indicate a sensitivity to wheat and other grains containing gluten, however a sensitivity can exist without Celiac Disease. Blood tests are only useful as part of the screening process for this disease, and are not sufficient to provide a diagnosis. If Celiac Disease is suspected, it is advised to rule it out before removing gluten from the diet.
So which test is best?
MRT is, in my experience, the most accurate, scientifically validated test currently available. Using these results, a personalized elimination diet such as LEAP can then be used to further identify any other adverse food/chemical reactions the test may have missed (as not all reactions involve the same pathways). IgE testing may be done to compliment this test, however the LEAP protocol will also help to identify IgE mediated reactions. This is possible LEAP entails that the safest 20-25 foods, based on the MRT results, are consumed for the first 10 days to allow for healing. At this point, foods are added back in one at a time, so that ANY reaction, if one should occur, can be easily identified. Thus, the MRT is a baseline test upon which an elimination diet like LEAP can be used to further test for all reactions. It’s truly individual and makes the whole process much easier. Children and adults alike can be tested and go through the LEAP protocol.
Why get tested?
I have yet to encounter a client (including myself) who has not tested positive for at least 6 food sensitivities, even if they were not experiencing noticeable symptoms. These reactions may go unnoticed, but cellular changes are undeniably taking place. The mediators released during an immune reaction to any given food have varying effects on the body, including changes in fluid retention, dilation or constriction of blood vessels, inflammation, blood pressure changes, increased sensitivity to pain, hormone imbalances, and more. Constant exposure leads to chronic inflammation, chemical disturbances, and tissue damage, which will eventually have a serious impact on your long-term health.
Getting tested is a useful tool for everyone, whether to manage a current condition like eczema, or to prevent future health problems.
About the Author: Megan Pennington is a Certified Holistic Health Coach with a Bachelor of Science degree in Dietetics and Human Nutrition. Her specialties include weight management, food reactions, inflammatory conditions, holistic nutrition, fertility issues, and transformational coaching.
She is the founder of MP Holistic Nutrition in Montreal and creator of the Essentials Whole Health Program. She works with clients both locally, internationally, and online to help them achieve the body they desire, a joyful relationship with food, and vibrant health. To connect with Megan, SIGN UP for FREE tips and updates!
Megan works extensively with the MRT test and is a Certified LEAP Therapist. She uses both MRT and LEAP to help jer clients with IBS, fibromyalgia, migraine disorders, chronic skin issues, digestive complaints, and other symptoms relating to food sensitivity and inflammation. For more information or to get tested (available in North America only), please check our her page on Food Sensitivity Testing.