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Do Food Sensitivity Tests Work And What Is The Best Test Out There?

  • Writer: Liz Riesen, RD
    Liz Riesen, RD
  • Sep 25
  • 5 min read

Updated: Oct 13

Many new clients come to me knowing that they are reacting to food they're eating, but may be unsure what foods and why this is happening to them. I know personally how frustrating it can be to be eating healthy food and yet suffering with symptoms of bloating and pain (to name just two).


The problem with food sensitivities is that multiple sensitivities often develop at one time, making it difficult to pinpoint on your own. Sensitivities are an immune cell reaction (like an allergy, but different immune cells). This means that they can also cause symptoms of:


• Fatigue • Brain fog • Headaches • Bloating and Gas • Diarrhea • Constipation


• Sinus Congestion • Rashes, Dry or Itchy Skin • Painful Joints


• Nausea • Abdominal pain • Water retention • Unexplained Weight Gain or Weight Loss


woman lying in bed holding stomach


What Are Food Sensitivities and Why Test for Them?


Food sensitivities differ from food allergies. While allergies involve an immediate immune response that can be severe, food sensitivities usually cause delayed reactions that are tougher to connect to a specific food. This is why I have used food sensitivity testing in my nutrition practice for over ten years.


Testing for food sensitivities helps uncover hidden triggers that might not be obvious through diet alone. For example, someone experiencing chronic headaches might not realize that corn or even garlic, is the cause. By identifying these foods, individuals can avoid them and improve their quality of life.


Benefits of Testing for Food Sensitivities


  • Personalized diet adjustments: Knowing which foods cause reactions allows for targeted elimination through a six-week personalized diet.

  • Improved digestion and energy: Removing trigger foods help reduce symptoms and calm inflammation in the GI tract allowing for better digestion.

  • Avoid unnecessary restrictions: Testing helps prevent cutting out foods in your diet that are actually safe and not contributing to symptoms.


If this image below makes you anxious, it's time to get you clear answers and healing!


table with bowls of different food

How Does Testing for Food Sensitivities Work?


There are several methods to test for food sensitivities, which can make it confusing to the public. Now that you understand food sensitivities are an immune cell reaction, you know the only way to accurately test for food sensitivities is through the blood (plasma) where immune cells reside.


1. Blood Tests


Blood tests measure immune system responses to specific foods by detecting immune cell response to individual food and food chemical proteins. Since our immune cells are present in our blood, a proper food sensitivity test should be via blood sample. However, there are are different food sensitivity blood tests on the market. Many measure only a single immune cell, usually IgG.


But, we actually have multiple types of immune cells outside our gut that can be reacting to foods. This is why I've used the Mediator Release Test (MRT) for over ten years in my practice. The MRT test measures the full reactivity of all immune cells when an individual food protein is introduced to the sample vial. The MRT currently tests 176 foods and food chemicals, so we are able to create a specific immune-calming diet for you based on these results that is realistic to follow for six weeks.


You can learn more and order your own MRT Food Sensitivity Test here. If you have any questions, please contact me directly at info@lizriesen.com



What about other tests on the market like saliva, hair, or skin prick? These do not measure immune cell reactivity and therefore are not tests that I recommend or use in practice.

Eye-level view of a healthcare professional preparing a blood test kit


Real Patient Experiences with the MRT Food Sensitivity Test


I'll share words from a few of my clients after working through food sensitivity testing and a healing diet with them. I like to note that while the comprehensive test gives us a great starting place, the personalized plans I make for my clients also take into consideration the individual patient's symptoms, health history, diet preferences, and goals. With all of this together we can create a healing plan that is effective and realistic for you.



"I was introduced to Liz through a friend of mine who is also suffering from an autoimmune disorder.

Long story short, working with Liz has honestly been one of the best decisions I have ever made. I have lost a ton of weight and I never get sick any more. While all my work colleagues are on their second or third round of colds/flu's, I'm still going strong. I'm just shy of 45 years old and my old job left me with some arthritis injuries, I'd also like to mention that the arthritis has cleared up as well. I feel much, much younger than I did eight weeks ago." - DM



"Following my MRT food sensitivity blood tests, Liz Riesen provided the guidance I needed to help heal my gut and rid myself of cramps, diarrhea, and fatigue. Over a period of three months, using the MRT test results, I consulted with Liz. Slowly but surely, I achieved my goals following her suggestions which foods to introduce until the next appointment. Liz also made herself readily available if I had any questions. Although my insurance does not cover the MRT test or consultations with Liz, I consider these dollars well spent since my quality of life has significantly improved. What better investment can a person make?" - Anne S



"Liz is very knowledgeable. I was having stomach issues, in the bathroom constantly and gaining weight. Since seeing Liz and her helping me with a food plan I have lost weight, no longer bloated and in the bathroom most of the day. I have more energy and sleep thru the night. I would definitely recommend Liz to family and friends." - Cathy B



"I had been seeing a wellness Doctor for over a year, but he was super expensive and things were not getting better. I knew food/diet was related to issues and while surfing the web, I found Liz. Boy, was I glad I did. I have my energy back, I don't get sick like I use to, my joints don't hurt. She has helped me so much and I have referred several friends and family members ALL who got help from Liz. She is so intelligent, so articulate, so willing and eager to help and super gifted! I am beyond thrilled to be a client of hers!" - Patti W



What You Can Expect


If you decide to pursue testing, here is a general overview of what to expect:


  1. Health History: Review symptoms and medical history with provider.

  2. Sample collection: You'll receive a test kit in the mail that you bring to your local lab for the blood draw. If you don't have a lab, I can help you find one.

  3. Laboratory analysis: The sample is analyzed for immune responses to various foods. This takes around ten business days.

  4. Results review: Together we'll review your results and create a personalized immuno-calm diet to follow for at least six weeks. Food introductions typically start after two weeks.

  5. Follow-up: Monitor symptoms and adjust the diet as needed.


This process takes several weeks but provides valuable insights into managing food-related symptoms and allows the body to heal for long-term relief of symptoms.



Moving Forward with Food Sensitivity Insights


Understanding your body's reactions to food is a powerful step toward better health and symptom relief. If you're interested in learning more about the Mediator Release Test (MRT) for food sensitivity testing, please visit my page www.lizriesen.com/sensitivities


You'll find a sample report and more information on the testing package through the link above. If you're ready to order your food sensitivity testing package, you can click here to get started today!




registered dietitian

Liz Riesen, Registered Dietitian 


Liz is a registered dietitian who has worked with food sensitivities for over ten years. She is LEAP certified, which is the gold-standard for assessing test results and creating a personalized immuno-calm diet based on symptoms and dietary needs.


You don't have to live with symptoms like bloating, stomach issues, fatigue, weight gain, anxiety, and more. Get the support and guidance necessary to feel confident and comfortable in your body.


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