Meals Sensitivity Exams: Which of them REALLY Work?

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Do Expensive Food Sensitivity Tests Work?

Are there cheaper (or free) ways to eradicate food sensitivities?

And, perhaps most importantly, what should people do with their results?

This article will tell you the answers to these questions (and more!), Including:


Why take a food sensitivity test?

When people choose to have a food sensitivity test, they usually want to feel better. For years they have suffered from upset stomach, flatulence, embarrassing gas or belching, abdominal pain, diarrhea and / or brain fog.

Even though they cut out any number of foods – gluten, dairy, onions, garlic – these problems persist.

So when they learn about food sensitivity tests that only take a fingerprint of blood, they're relieved. You can't wait to find out what's going on – and finally get back to life without an awkward digestive emergency lurking around the corner.

How do I know?

As a registered nutritionist, I have advised hundreds of people with mysterious and insane GI issues.

Also, I was practically born with an upset stomach.

During my childhood, my mother took me from one specialist to another. Medical experts suggested I might be gluten sensitive. Or maybe dairy.

Or gluten and dairy products?

No matter what I stopped eating, I just couldn't get rid of my digestive problems.

By the end of high school, I ran the runs almost every day.

If you can imagine that, you can no doubt understand why I chose to major in nutrition and eventually become a registered nutritionist. I looked for answers to solve the problem once and for all.

Perhaps you can also understand why during my freshman year in college I found myself in the waiting room of a naturopathic doctor offering tests for food sensitivity.

Regardless of what the test showed that day, it would take me years to figure out what was really wrong. And this long search has taught me many important lessons.

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The best ways to identify and deal with food sensitivities.

Most people can test for food sensitivities and intolerances at home – without needles, blood tests, or special kits.

At home, options like recording foods and diets for elimination aren't as simple as pricking your finger and draining your blood to a laboratory. However, they are more accurate and effective.

And there is this: some people – myself included – can relieve their symptoms without going without a single meal.

In other words, millions of people believe that they cannot eat dozens of foods when in reality only a few (and in some cases none) of those foods are actually a problem for them.

I will examine all of that in this article, delving deeply into the latest scientific knowledge and my personal experiences.

I hope what you are about to learn will not only help you understand what is actually going on, but will also enable you to eat a variety of foods again without fear. (Connected: "What foods should I eat?" Your three step guide to choosing the best foods for your body.)

Let's start with some definitions.

What are food sensitivities?

Some people use the term “food sensitivity” as a collective term to describe a variety of adverse symptoms that can be caused by eating certain foods

Other people define sensitivities more narrowly.2 They are left with food sensitivities when the following problems are excluded

  • Food allergies: When the immune system mistakenly treats a part of a food as a germ. This can lead to a variety of allergic reactions: hives, swelling, vomiting, diarrhea, and life-threatening drops in blood pressure.
  • Food intolerances: The inability to process or digest certain foods. For example, someone who is lactose intolerant does not have sufficient amounts of digestive enzymes necessary to break down lactose, a sugar found in dairy products.
  • Celiac Disease: An autoimmune reaction that causes bowel inflammation and diarrhea when someone consumes gluten, a protein found in many grains, especially wheat.

Still other people use the word "sensitivity" interchangeably with "intolerance". They flip the term IBS (short for irritable bowel syndrome) and try to indicate that something in the diet is making someone sick, but they are unsure of the culprit.

It's all pretty confusing so let's just do it.

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

Types of Food Sensitivity Tests: What Works?

Okay, so let's get back to what I started telling you at the beginning of this article – about the day I underwent food sensitivity testing.

The naturopath pricked my finger and sent a few drops of my blood to a laboratory.

About a week later, the doctor gave me a 10-page report showing that I had a "weakened" immune response to dozens of foods: sugar, dairy products, cooking oil, gelatin, baking powder, cornstarch, chocolate, butter, cheese, popcorn , pretty much all grains, veal, liver, beef, tree nuts, corn, Brussels sprouts, and cabbage.

As I looked at the report, I was thinking about the food that is normally served in the campus dining room.

I wanted clear answers and a workable plan to make it happen. Instead, I felt overwhelmed and helpless. How could I eliminate all of these foods for the rest of my life?

Is the IgG Food Sensitivity Test Accurate?

A laboratory uses a food sensitivity test to analyze how immunoglobulin G (IgG), an antibody made by the immune system, reacts to around 100 different foods. The idea is that elevated IgG levels signal food sensitivity.

This premise seems logical.

This, after all, is similar to the premise of a food allergy blood test, which measures another antibody called immunoglobulin E (IgE).

When IgE levels are elevated, it indicates that people's immune systems are pumping out substances that cause parts of the body to swell, develop a rash, switch off, and / or expel things from the GI tract (a.k.a. vomiting).

Although IgE tests can give false positive results, they are relatively accurate 70 to 90 percent of the time and correctly diagnose allergies.4 This is how you can tell if you have a nut allergy, for example.

Unlike IgE tests, IgG tests are not regulated and not proven.

The few studies that appear to support IgG testing have been criticized for a variety of design flaws

(For information about how to read a study, see Reading Scientific Research.)

The premise behind IgG testing has also been questioned. That's because increased IgG probably isn't a bad thing. Most experts consider it a normal immune response.

Our bodies are likely to develop IgG antibodies to all of the foods we eat.

These antibodies can even be how the body marks a substance as "safe".

As the following table shows, those with high IgE are likely to have a food allergy. If the IgE is low and the IgG is high, it is a sign that the body has become tolerant of a certain food

Probably a food allergy High Low
Probably food tolerance Low High

In other words, if your blood reacts with IgG to a particular food, it probably doesn't mean you are sensitive to it. Rather, it may mean that you recently ate this food.5,7

For this reason, the following organizations strongly recommend that you do not perform IgG testing for food sensitivity:

  • American Academy of Allergy, Asthma, and Immunology3
  • The Canadian Society for Allergy and Clinical Immunology8
  • The European Academy of Allergy and Clinical Immunology7

As the Canadian Society for Allergy and Clinical Immunology put it:

"Inappropriate use of this test (IgG sensitivity to food) only increases the likelihood of false diagnoses, resulting in unnecessary dietary restrictions and decreased quality of life."

3 major disadvantages of IgG testing

You may be thinking, what if IgG testing is not proven? Does it really matter if someone wastes money on a test that doesn't work?

It's important – for at least three important reasons. An inaccurate blood test with food sensitivity can mean:

  1. You keep eating foods that could be causing your problems because those foods did not respond to the IgG in your blood.
  2. You stop eating lots of foods that are perfectly okay with you. That's not fun. Worse, you could develop nutritional deficiencies.
  3. You cannot diagnose the real problem. This was the case with me. About fifteen years after my IgG test, I had a colonoscopy. It showed a rare, incredibly slow, genetic ovarian tumor – one that I've probably had since I was born. The tumor had grown outside of my ovary and through the wall of my digestive tract. After I removed my cancer, my digestive problems went away.

Important note: All three disadvantages – particularly the risk of nutritional deficiencies – are compounded when children are involved.

In addition to the disadvantages listed above, as they age, young children are more likely to develop allergies and / or sensitivities to these foods if they are pampered and not exposed to different foods

All of this begs the question: How do you find out if you really have food sensitivities? And if so, what should you do about it?

6 problems that mimic food sensitivities

I thought I had food sensitivities. In reality, I had cancer – a tumor that had invaded my digestive tract.

However, my situation is incredibly rare. Most people with gas and diarrhea do not have cancer. However, the following are much more common:

1. A tendency to swallow dinner

When we eat quickly, we swallow air bubbles, which lead to a puffy, bloated, gaseous feeling.

And because it takes time for the “I'm full” signal from the stomach and intestines to reach the brain, eating quickly often triggers overeating, which only adds to the uncomfortable discomfort after eating.

(If you're looking for a strategy that might help here, take a look at this the 30 day slow eating challenge.)

2. Too much fiber too fast

Some people experience stomach pain, gas, and gas after suddenly increasing their fiber intake.

For example, a customer might decide to eat nine servings of vegetables for a New Year's resolution. If you haven't eaten a lot of vegetables before, this sudden change will overload the peristalsis muscles of the GI tract and disrupt the flora that lives in the gut.

If you temporarily reduce your fiber intake and then slowly increase it, you will feel much better.

3. Not enough fluids

Water is also incredibly important as it helps move stool through the digestive tract. Getting enough is important when someone is increasing their fiber intake.

A good general rule: adding a serving or two of fiber increases your water consumption by 1-2 glasses.

4. Imbalance of the intestinal flora

Antibiotics can wipe out the amount of friendly gut bacteria, allowing more problematic insects to take control and lead to diarrhea and other symptoms.

Starting Lactobacillus rhamnosus GG (for children) or Saccharomyces boulardii (for adults) within two days of your first antibiotic dose may help reduce the risk of antibiotic-associated diarrhea

5. Stress and lack of sleep

Stress diverts blood flow away from the GI tract, making it difficult for the body to digest food effectively. Bottom line: gas, pain, and gas.

Before eating, I encourage my clients to try a box breathing sequence:

  • Inhale for 4 seconds.
  • Hold down for 4 seconds.
  • Exhale for 4 seconds.
  • Hold down for 4 seconds.
  • Repeat 3 to 5 times.

This short breathing exercise induces relaxation, directs blood flow to the GI tract, and prepares it to digest the foods to be consumed. It can also help people slow down.

Bottom line: heartburn, stomach pain, and gas subsides.

(For more strategies to reduce stress, see: How stress prevents weight loss.)

6. Aversion to food

Sometimes the mere thought of a meal can make someone sick even though the mechanism is not fully understood.

These aversions are common in young children who have become sick after consuming a certain food – for example, due to food poisoning or stomach flu. Your brain then seems to associate the feeling of nausea with eating.

Free Ways To Test The Sensitivity Of Food – At Home

When clients come to me with GI symptoms, I use two different tools to help them relate what they eat to what they feel.

Tool # 1: food journal

For about a month, my clients follow the following:

  • What they eat and drink
  • How they eat (for example, sipping fast food while driving to an appointment or slowly enjoying a homemade meal)
  • How much they eat (until just satisfied versus filled)
  • How you feel and particularly bothersome symptoms like diarrhea, headache, gas and stomach pain
  • How they sleep
  • Your stress level

Once they have 30 days of data, we look at their diary entries looking for patterns.

To highlight these patterns, I'd like to draw a customer's attention to days when they experienced bothersome symptoms like upset stomach. Then I ask:

“What do you notice in your diary in the two to three days before this flare-up? Do you see something interesting? "

If necessary, I also point out periods when there were no symptoms at all – and I ask the same question:

“What do you notice in the days leading up to this good route? Did you do anything different in those days than the days before the flare-up? "

This journaling exercise will help people identify sensitivities and realize that they may not have as many sensitivities as they thought they were.

For example, after reviewing their diary, a customer might say, "Whoa, I accidentally had dairy on Sunday and didn't have diarrhea the next day. That's really weird. But I had diarrhea almost every day that other week – and I ate perfectly back then. But I was super stressed. Do you think there is a connection? "

Would you like to try this on yourself or a client? Download this free Food and Feelings Journal to get started.

An illustration of a food journal that you can use to determine the sensitivity of food. In the diary, you can keep track of how many hours you slept each day and rate your stress from 1 to 10. Here you can enter the time at which you ate each meal, what you ate, how you ate (e.g. slowly and carefully or quickly over the sink) and what you noticed (e.g. a blocked one Nose an hour after eating or nothing felt okay).

An easy way to identify food sensitivities.

Tool # 2: The Elimination Diet

Elimination Diets Much like a science experiment, work to help people identify foods that lead to a variety of bothersome symptoms. And they pretty much do what the name suggests: exclude certain foods for a short period of time – usually three weeks.

After three weeks, customers slowly reintroduce certain foods one at a time, with each reintroduction a few days apart. They monitor their symptoms for possible reactions. Unlike food sensitivity blood tests, elimination diets are the gold standard for identifying food sensitivities.

The problem with elimination diets? You need time and effort.

Do I wish I had some fancy, high tech, super science method (like a blood test) to give customers a definitive answer? Absolutely. I do. Because a failed blood test (for most people) is easier than food protocols and elimination diets.

However, right now, this trial-and-error approach to testing different foods is the best we have.

But … we have a tool that makes it easier: Precision Nutrition's FREE eBook, The Ultimate Guide to Elimination Diets.

This easy-to-use resource contains extensive grocery lists, recipes, and complete guides – everything you need to know to try an elimination diet on yourself for a customer. (And like I said, it's 100 percent free.)

How to Talk to Customers About Food Sensitivity Testing

If you're a nutrition coach, you may have had the following experience: A customer tells you that a food sensitivity test only showed that they couldn't eat 47 different foods.

Perhaps it is a young parent who is exhausted and trying to find dinner that all three children will eat.

"It's hard enough to cook for my family and make them nutritious, and now I have 47 things on my list that I can't eat anymore," says the customer. "What should I do?"

Despite my reservations about blood tests for food sensitivity, I never start by debunking anyone's test results. That would only make her more confused and possibly alienate her.

Instead I say something like this:

“If you want to jump in and cut out this food, we can start there. But if you don't mind, I'd love to talk about where you eat, why you eat, and how you eat. Because everything is related to what you eat and how you feel. "

From there, I usually ask clients a lot of questions:

  • How long does it take you to eat your meals?
  • How is your sleep
  • Do you usually eat at home … or do most meals take place elsewhere, such as in the car?
  • How would you describe your stress level?

This conversation often opens the door to food journaling. This is key because, as mentioned earlier, a food journal can help customers identify for themselves what is causing symptoms and what is not.

For people with multiple food sensitivities, this tool makes meal planning easier.

Let's get back to the parent I mentioned in the previous section. How can you help someone who, legitimate or not, has a list of 47 foods they can't eat?

Put the spotlight on everything they can eat instead of emphasizing what they can't.

To do this, I print out lists of foods in the following categories: lean protein, vegetables, smart carbohydrates, and healthy fats. Working with a customer, we circle all the food they can eat.

Then I ask customers to pick their favorites 10 to 15 in each category.

Once they know their favorites, they can search cookbooks and hotplates for recipes and food ideas that contain these ingredients. (Psst: the local library often has all the cookbooks they need.)

Knowledge can really be life changing.

I am happy to announce that my last scans did not show any signs of cancer in my body. Even better, I now know that I can safely eat many, many foods that I once thought were forbidden to me.

Like Brussels sprouts, which happens to be one of my all time favorite vegetables. Oh, and chocolate. Definitely glad that food has returned to my life.

This has to be repeated: most people with digestive problems do not have cancer. Unlike me, they may have a food sensitivity or two.

Or maybe they have no food sensitivity at all – they have one of the six (common) problems that mimic food sensitivities.

Our psychological state and our ability to deal with stress have a much greater impact on digestion than most people realize.

And whether or not they have a sensitivity, many people may avoid many foods that they might be eating. And they live in fear that the meal they have just consumed will run them to the nearest bathroom.

For these people, food journaling and elimination diets can not only save money, but also be insightful and empowering. These free tools can help them enjoy food (and life!) Again.


Click here to view the sources of information referenced in this article.

1. General information on food allergies and sensitivities. University of Nebraska Department of Agriculture and Natural Resources.

2. Campos M. Food allergy, intolerance or sensitivity: what's the difference and why is it important? Harvard Health Publishing, Harvard Medical School.

3. Definition of food tolerance. American Academy of Allergy, Asthma, and Immunology.

4. Abrams EM, Sure SH. Diagnosing and treating food allergies. CMAJ. 2016, October 18; 188 (15): 1087-93.

5. Kelso JM. Unproven diagnostic tests for side effects on food. J Allergy Clin Immunol Pract. 2018 Mar; 6 (2): 362-5.

6. Jones SM, Pons L., Roberts JL, Scurlock AM, Perry TT, Kulis M. et al. Clinical efficacy and immune regulation with oral peanut immunotherapy. J Allergy Clin Immunol. 2009 Aug; 124 (2): 292-300, 300.e1-97

7. Stack SO, Asero R., Ballmer-Weber BK, Knol EF, Strobel S., Vieths S. et al. Testing for IgG4 against food is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008 Jul; 63 (7): 793-6

8. Carr S., Chan E., Lavine E., Moote W. CSACI Statement on Testing of Food Specific IgG. Allergy Asthma Clin Immunol. 2012, July 26; 8 (1): 12.

9. Chin B, Chan ES, Goldman RD. Early exposure to food and food allergies in children. Can Fam doctor. 2014 Apr; 60 (4): 338-9

10. Blaabjerg S., Artzi DM, Aabenhus R. Probiotics for the prevention of antibiotic-associated diarrhea in outpatients – A systematic review and meta-analysis. Antibiotics (Basel). 2017, October 12; 6 (4). Available from:

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