Food Sensitivity Tests: Which ones REALLY Work?

When you have food allergies, you’re always on the lookout for ways to avoid every possible trigger for you allergic reaction. A food sensitivity test is a method that you can use to find out if you truly have food allergies and which ones, or how many of them. This way, you may be able to avoid a serious allergic reaction and lose weight at the same time.

Sensitivity to certain foods is something many people experience, and often there is a strong link between food sensitivities and food intolerances. A food sensitivity is something that your body reacts to in a way that is different than it reacts to the regular food you eat. But Do Sensitive People Really Have Food Sensitivities?

The topic of food sensitivity tests is often a heatedly-debated topic in the world of nutrition. Often, people who have food sensitivities don’t realize that they have any sensitivities to begin with, and many find that their health problems are actually caused (not exacerbated) by other factors. A food sensitivity test will usually result in a test “pass/fail” result, and the most common “test” used these days is the “Reverse Sandwich Index”, or RSI.

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Do food sensitivity tests that cost a lot of money really work?

Is there a less expensive (or even free) method to identify food sensitivities?

What should individuals do with their findings, maybe most importantly?

You’ll find the answers to those questions (and more!) in this article, which includes:


What is the purpose of a food sensitivity test?

When individuals opt to take a food sensitivity test, they generally want to feel better as soon as possible. Stomach discomfort, bloating, embarrassing gas or belching, abdominal pain, diarrhea, and/or brain fog have plagued them for years.

Their issues continue after eliminating a variety of foods—gluten, dairy, onions, garlic, and the list goes on.

So they’re relieved to hear about food sensitivity tests that just need a drop of blood from a finger prick. They can’t wait to figure out what’s wrong and go back to enjoying a normal life without the threat of a digestive emergency.

How did I get to this conclusion?

I’ve advised hundreds of individuals with strange and perplexing GI issues as a licensed dietitian. 

In addition, I was born with a stomach ache.

My mother used to take me to several specialists throughout my childhood. Medical professionals speculated that I may be gluten intolerant. Or maybe dairy.

Or what about gluten and dairy?

I couldn’t seem to get rid of my stomach problems no matter what I stopped eating.

I had the runs almost every day towards the end of high school.

If you can picture that, it’s no surprise that I chose to study in nutrition and ultimately become a registered dietitian. I was searching for solutions to assist me finally solve the issue.

Perhaps you can see why, during my freshman year of college, I ended myself in the waiting room of a naturopathic physician who provided food sensitivity testing.

Regardless of the results of the test that day, it would take me years to figure out what was truly wrong. And it was during that lengthy quest that I learned many valuable things.

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The most effective methods for detecting and treating food sensitivities.

Food sensitivities and intolerances may usually be tested at home without the need of needles, blood tests, or special kits. 

Though food journaling and elimination diets aren’t as simple as pricking your finger and sending your blood to a lab, they’re more precise and effective.

And then there’s this: some individuals, like me, can get rid of our symptoms without giving up any foods.

To put it another way, millions of individuals believe they can’t consume dozens of foods while, in fact, just a few (and in some instances none) of them constitute a problem.

In this post, I’ll go over all of that, delving into the newest research as well as my own personal experiences.

It’s my goal that what you’re about to discover not only clarifies what’s going on, but also enables you to consume a broad range of foods without worry once again. (See also: ‘What should I eat?’) Your three-step approach to eating the healthiest meals possible.)

Let’s begin with a few of definitions.

What are food sensitivities, and how can you know if you have them?

Some individuals use the phrase “food sensitivities” to refer to a broad variety of negative symptoms that may be triggered by particular meals. 1

Others use a more limited definition of sensitivity. 2 When the above issues have been ruled out, food sensitivities are what’s left.

  • Dietary allergies occur when the immune system misidentifies a food component as a germ. Hives, swelling, vomiting, diarrhea, and life-threatening decreases in blood pressure are all possible adverse reactions.
  • Food intolerances are a condition in which a person is unable to absorb or digest certain meals. Lactose intolerance, for example, is caused by a lack of digestive enzymes that are required to break down lactose, a sugar found in dairy products.
  • Celiac disease is an immunological response that occurs when a person eats gluten, a protein present in a variety of cereals, most notably wheat.

Others use the terms “sensitivity” and “intolerance” interchangeably. They use the term IBS (irritable bowel syndrome) to imply that something in a person’s diet is making them ill, but they can’t pinpoint what it is.

It’s all a little complicated, so let’s break it down.

For the purposes of this story, I’ll borrow a definition from the American Academy of Allergy Asthma & Immunology: “A food sensitivity occurs when a person has difficulty digesting a particular food.”3

What are the different types of food sensitivity testing and how do they work?

So, let’s go back to what I was talking about at the start of this article—the day I went through food sensitivity testing.

My finger was pierced by the naturopath, who then sent a few droplets of blood to a lab.

A week later, the doctor handed me a 10-page report claiming that I had a “weak” immune response to dozens of foods, including sugar, dairy, cooking oil, gelatin, baking powder, cornstarch, chocolate, butter, cheese, popcorn, almost all grains, veal, liver, beef, tree nuts, corn, Brussels sprouts, and cabbage.

As I read through the article, I thought of the food provided at the college dining hall.

I’d hoped for clear answers and a feasible strategy to implement. Instead, I was left feeling powerless and overwhelmed. I didn’t think I’d be able to live without all of those meals for the rest of my life.

Is food sensitivity testing based on IgG accurate?

A lab examines how immunoglobulin G (IgG), an immune system antibody, responds to approximately 100 different meals during food sensitivity testing. Elevated IgG levels are thought to indicate dietary sensitivity.

This premise seems to be reasonable.

After all, food allergy blood testing, which detects a separate antibody called Immunoglobulin E, is based on the same concept (IgE).

When IgE levels are high, it means the immune system is releasing chemicals that cause portions of the body to enlarge, break out in a rash, shut down, and/or expel items from the GI tract (a.k.a. vomiting).

IgE tests are generally reliable, accurately identifying allergies 70 to 90% of the time, despite the possibility of false positives. 4 This is how you can tell whether you have a nut allergy, for example.

IgG testing, in contrast to IgE tests, are unregulated and untested.

The few studies that seem to support IgG testing have been chastised for a number of faults in their design. 5

(See How to interpret scientific research for further information on what to look for in a study.)

IgG testing’s concept has also been put into doubt. That’s because having high IgG levels isn’t always a negative thing. The majority of specialists believe it is a natural immunological response.

All of the foods we consume are likely to produce IgG antibodies in our bodies.

These antibodies may even be how the body determines whether or not a chemical is “safe.”

When IgE levels are high, someone is likely to have a food allergy, as seen in the graph below. When IgE levels are low and IgG levels are high, the body has grown tolerant to a specific meal. 6

  IgE IgG
Food allergy is very likely. High Low
Food tolerance is most likely. Low High


To put it another way, just because your blood responds with IgG to a certain meal doesn’t imply you’re allergic to it. It’s more likely that you’ve consumed that meal lately. 5,7

As a consequence, the following groups strongly advise against using IgG food sensitivity tests:

  • American Academy of Allergy, Asthma & Immunology3
  • The Canadian Society of Allergy and Clinical Immunology (Canadian Society of Allergy and Clinical Immunology)8
  • The European Academy of Allergy and Clinical Immunology is a non-profit organization dedicated to improving allergy and clinical immunology in Europe. 7

According to the Canadian Society of Allergy and Clinical Immunology:

“The improper use of this [IgG food sensitivity] test raises the risk of erroneous diagnoses, resulting in needless dietary restrictions and a worse quality of life.”

Three major drawbacks of IgG testing

Perhaps you’re wondering, “What if IgG tests haven’t been proven?” Is it really so important if someone spends money on a useless test?

It is significant for at least three reasons. An incorrect food sensitivity blood test may indicate:

  1. You keep eating items that may be causing your problems since they don’t respond to the IgG in your blood.
  2. You give up a lot of items that are absolutely healthy for you. That’s not a lot of fun. Worse, you may have nutritional deficiency.
  3. You are unable to identify the actual issue. This was my experience. I had a colonoscopy around fifteen years following my IgG test. It showed that I had a rare, slow-moving hereditary ovarian tumor that had been present since birth. Outside of my ovary, the tumor had grown through the wall of my digestive system. My stomach issues disappeared when I had my malignancy removed.

Important note: When children are involved, all three of these drawbacks—particularly the danger of dietary deficiencies—intensify.

In addition to the disadvantages mentioned above, when young children are coddled and kept from being exposed to different foods, they are more likely to acquire allergies and/or sensitivities to those foods as they grow older. 9

All of this raises the question: how can you tell whether you have food sensitivities or not? And if you do, what are your options for dealing with them?

6 issues that resemble food sensitivities

I used to believe I had food allergies. In fact, I was suffering from cancer, a tumor that had spread throughout my digestive system.

My circumstance, on the other hand, is very unusual. The majority of individuals who have bloating and diarrhea do not have cancer. The following, on the other hand, are much more common:

1. A tendency to eat dinner quickly

We swallow air bubbles when we eat rapidly, resulting in a puffy, bloated, gassy sensation.

Because it takes time for the “I’m full” signal from the stomach and intestines to reach the brain, rapid eating often leads to overeating, which further adds to the uneasy feeling that follows a meal.

(Check out the 30-day slow eating challenge for a technique that may be useful here.)

2. Consumption of too much fiber in a short period of time

After abruptly increasing their fiber consumption, some individuals suffer stomach discomfort, gas, and bloating.

For example, a customer may make a New Year’s goal to consume nine servings of veggies. This abrupt shift will overwork the GI tract’s peristalsis muscles and disrupt the gut flora if they haven’t eaten many vegetables previously.

They feel much better when they briefly decrease their fiber intake and then gradually increase it.

3. Inadequate fluid intake

Water is also crucial because it aids in the passage of feces through the digestive system. If one’s fiber intake is being increased, getting enough becomes critical.

A good general guideline is to increase your water intake by 1-2 glasses when adding a serving or two of fiber.

4. Unbalanced gut flora

Antibiotics may deplete quantities of beneficial gut bacteria, enabling more troublesome germs to take control, resulting in diarrhea and other symptoms.

Within two days after your first antibiotic dosage, start Lactobacillus rhamnosus GG (for children) or Saccharomyces boulardii (for adults) to help decrease the risk of antibiotic-associated diarrhea. 10

5. Anxiety and sleep deprivation

Stress causes blood flow to be diverted away from the GI tract, making it more difficult for the body to digest food properly. Gas, bloating, and discomfort are the end results.

Before meals, I recommend that my clients practice Box Breathing:

  • Inhale for 4 seconds and exhale for 4 seconds.
  • Hold the position for 4 seconds.
  • 4 seconds of exhalation
  • Hold the position for 4 seconds.
  • Rep 3–5 times more.

This quick breathing technique aids relaxation by increasing blood flow to the GI system, which prepares it to digest the meal about to be consumed. It may also aid in the slowing down of individuals.

Heartburn, stomachaches, and bloating subside as a consequence.

(Read How stress hinders weight loss for additional stress-reduction methods.)

6. Aversion to certain foods

Though the process isn’t completely understood, the mere idea of a meal may make someone ill.

These aversions are common in young infants who have been ill after eating a specific meal, such as from food poisoning or stomach virus. Their brain then seems to connect the nausea to the meal.

Food sensitivities may be tested for free at home.

I utilize two distinct methods to assist clients link what they eat with how they feel when they come to me with GI issues.

Food journaling is the first tool.

My clients keep note of the following for around a month:

  • What they consume in terms of food and drink
  • The way they eat (for example, wolfing down fast food while driving to an appointment vs. slowly savoring a home-cooked meal)
  • How much food do they consume? (until just satisfied versus stuffed)
  • How they’re feeling, particularly if they’re experiencing symptoms like diarrhea, migraines, bloating, or stomach discomfort.
  • What people do to sleep
  • Their degree of anxiety 

We examine their journal entries for trends once they’ve accumulated 30 days of data.

I prefer to draw a client’s attention to days when they had bothersome symptoms, such as stomach discomfort, to emphasize such trends. Then I pose the following question:

“In the two to three days preceding up to that flare up, what do you note in your journal? “Did you see anything interesting?”

I also call attention to any periods of time when they had no symptoms at all, if relevant, and I ask the same question:

“In the days preceding up to this excellent stretch, what do you notice? Did you do anything differently over those days than you did in the days before the flare-up?”

This journaling activity aids in the identification of sensitivities as well as the realization that they may not have as many as they believed.

“Whoa, I inadvertently ate dairy on Sunday, and I didn’t have any diarrhea the following day,” a customer may remark after reviewing their diary. That’s a strange situation. However, I had diarrhea almost every day the previous week, despite the fact that I was eating properly at the time. But I was very tense. Do you believe there’s a link?”

Do you want to give it a go with yourself or a client? To get started, download this free Food and Feelings Journal.

An illustration of a food journal you can use to help identify food sensitivities. Each day, the journal has you track how many hours you slept and to rate your stress levels from 1-10. It has space to enter the time you ate each meal, what you ate, how you ate (for example, slow and mindfully or fast over the sink), and what you noticed (for example, a stuffy nose an hour after eating or nothing, felt okay).

A simple method for determining food sensitivities.

The elimination diet is the second tool.

Elimination diets operate in a similar way to a scientific experiment in that they assist individuals discover items that cause a variety of symptoms. And they do exactly what their name implies: they restrict specific meals for a certain amount of time, typically three weeks.

Clients gradually reintroduce particular foods one at a time after three weeks, with each reintroduction spaced a few days apart. They keep an eye on their symptoms for any potential responses. Elimination diets, rather than food sensitivity blood testing, are the gold standard for detecting food sensitivities.

What’s the issue with elimination diets? They require time and effort to complete.

Do I wish I had a sophisticated, high-tech, super-scientific method to offer customers a definite answer (like a blood test)? Absolutely. Yes, I do. Because food diaries and elimination diets are more difficult (for most people) than a sophisticated blood test.

For the time being, though, this trial-and-error method to trying out new meals is the best we have.

But there’s a tool that may help: The Ultimate Guide to Elimination Diets, a free booklet from.

This user-friendly guide contains detailed food lists, recipes, and step-by-step instructions—everything you need to attempt an elimination diet on yourself or with a client. (And, as I have said, it is completely free.)

How to explain food sensitivity tests to clients

Maybe you’ve had this scenario as a nutrition coach: a client informs you that a food sensitivity test showed they can’t eat 47 different foods.

Perhaps it’s a young mom who’s exhausted from trying to locate meals that all three children will eat.

“It’s difficult enough to prepare for my family and keep it healthy, and now I have a list of 47 things I can’t eat,” the customer adds. “What am I meant to do?” says the narrator.

Despite my concerns regarding food sensitivity blood testing, I never begin by attempting to disprove someone’s findings. That would just confuse them more and perhaps alienate them.

Instead, I’ll say something along these lines:

“We can start there if you want to jump in and take those meals out. But, if it’s okay with you, I’d want to speak about where you eat, why you eat, and how you eat. Because everything is linked to what you eat and how you feel..”

Following that, I typically ask a number of questions to my clients:

  • How long do you spend eating your meals?
  • How do you sleep at night?
  • Do you eat at home most of the time… or do most meals take place elsewhere, such as in the car?
  • What would you say your stress level is?

This discussion often leads to food journaling. That’s important because, as I previously stated, a meal diary may help clients identify what causes symptoms and what doesn’t.

This app makes meal planning simple for individuals with various food sensitivities.

Let’s return to the parent I discussed before in this section. How can you assist someone who has a 47-item “can’t eat” list, whether legitimate or not?

Instead of highlighting what kids can’t consume, shine a focus on what they can.

To accomplish so, I create lists of items that fall into the following categories: lean proteins, vegetables, smart carbohydrates, and healthy fats. We circle all of the items that a client can consume while working together.

Then I ask customers to choose their top 10 to 15 items from each category.

Once they’ve decided on their favorites, they may look for recipes and meal ideas using those items in cookbooks and on culinary websites. (Hint: the local library usually has all of the cookbooks they need.)

Knowledge has the power to transform lives.

I’m pleased to report that my most recent scans revealed no signs of cancer in my body. Even better, I now know that I can consume a variety of things that I previously believed were off-limits to me.

For example, Brussels sprouts are one of my all-time favorite veggies. Oh, and there’s chocolate. I’m overjoyed that food has resurfaced in my life.

It’s worth repeating: the majority of individuals who suffer digestive issues don’t have cancer. They, unlike me, may have one or more dietary sensitivities.

Perhaps they don’t have a food sensitivity at all, but are suffering from one of the six (common) problems that resemble food sensitivities.

Most individuals are unaware that our psychological condition and capacity to handle stress has a far greater effect on digestion than they think.

And, whether or not they have a sensitivity, many individuals may be avoiding a wide range of foods. And they’re terrified that the dinner they just ate will send them rushing to the closest restroom.

Food blogging and elimination diets may not only save these individuals money, but they can also be enlightening and uplifting. These free tools may help them rediscover the pleasure of eating (and life!).


To see the information sources mentioned in this article, go here.

1. Information about Food Allergies and Sensitivities in General Institute of Agriculture and Natural Resources at the University of Nebraska.

2. Campos M. What Is the Difference Between Food Allergy, Intolerance, and Sensitivity, and Why Does It Matter? Harvard Medical School, Harvard Health Publishing

3. Define food intolerance. The American Academy of Allergy, Asthma, and Immunology is a professional organization dedicated to allergy, asthma, and immunology.

CMAJ. 2016 Oct 18;188(15):1087–93. 4. Abrams EM, Sicherer SH. Diagnosis and treatment of food allergy.

Unproven Diagnostic Tests for Food Adverse Reactions, Kelso JM. 2018 Mar;6(2):362–5. J Allergy Clin Immunol Pract.

6. Jones SM, Pons L, Roberts JL, Scurlock AM, Perry TT, Kulis M, et al. Jones SM, Pons L, Roberts JL, Scurlock AM, Perry TT, Kulis M, et al. Peanut oral immunotherapy: clinical effectiveness and immunological modulation. 2009 Aug;124(2):292–300, 300.e1–97 in J Allergy Clin Immunol.

7. Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, et al. Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, et al. As a diagnostic technique, testing for IgG4 against foods is not recommended: Allergy. 2008 Jul;63(7):793–6. EAACI Task Force Report.

8. Carr, S., Chan, E., Lavine, E., and Moote, W. Statement of position on the testing of food-specific IgG. 2012 Jul 26;8(1):12 in Allergy Asthma Clin Immunol.

Early exposure to food and food allergy in children. Chin B, Chan ES, Goldman RD. Can Fam Physician, 60(4), 338–39, April 2014.

Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Outpatients: A Systematic Review and Meta-Analysis. Blaabjerg S, Artzi DM, Aabenhus R. Antibiotics are drugs that are used to treat infections (Basel). 12 Oct 2017;6 (4). Antibiotics 6040021 is available at

If you’re a coach or wish to be one…

It’s both an art and a science to guide clients, patients, friends, or family members through healthy food and lifestyle adjustments in a manner that’s tailored to their individual body, tastes, and circumstances.

Consider the Level 1 Certification if you want to learn more about both.


There’s no question the food sensitivity testing industry has spiced up in recent years. Many test panels are available for purchase online or in stores, promising to show you how many of your potential food allergies you have (and thus, how to avoid them). Some of these tests are fairly well known, such as the IgG Food Sensitivity test, but others are more questionable, and even fraudulent.. Read more about food sensitivity test reddit and let us know what you think.

Frequently Asked Questions

Do food sensitivity tests actually work?

There are a few different tests that you can take to determine whether or not you have food sensitivities. The most common one is the elimination diet, which involves eliminating certain foods from your diet for a period of time and then reintroducing them one by one to see if there are any reactions.

What is the most accurate food allergy test?

The most accurate food allergy test is the IgE RAST test.

How accurate is blood testing for food sensitivities?

Blood testing is not an accurate way to determine food sensitivities.

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Una is a food website blogger motivated by her love of cooking and her passion for exploring the connection between food and culture. With an enthusiasm for creating recipes that are simple, seasonal, and international, she has been able to connect with people around the world through her website. Una's recipes are inspired by her travels across Mexico, Portugal, India, Thailand, Australia and China. In each of these countries she has experienced local dishes while learning about the culture as well as gaining insight into how food can be used as a bridge between different cultures. Her recipes are often creative combinations of traditional ingredients from various different cuisines blended together to create something new.