Four Reasons Wheat is Triggering Your SIBO Symptoms

A hot, freshly baked buttery roll…delicious.

A steaming bowl of macaroni and cheese….so comforting

Eating pizza with your friends and family…..priceless

You like your freedom of being able to eat what you want.

But you just can’t get rid of this nagging feeling in the back of your mind. You see the shelves of gluten free products in the grocery store.

Maybe there is something to this gluten free craze. Would it help my bloating, diarrhea, constipation and other SIBO symptoms if I went gluten free?

No, it can’t be. I like wheat too much!

You are in quite the quandary.

Believe me, I was there. I’ve followed the gluten free movement, with interest and sometimes disdain. But I would tell myself, I don’t have a problem with wheat. That’s not me. I’m not one of those people.

Even though I was struggling with irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) for more years than I wanted to count.

Isn’t wheat a part of our culture? We eat it at breakfast, lunch, dinner, even snacks! It is one of the most commonly consumed cereal grains worldwide.

But eating wheat has come at a price.

It is estimated that nearly 10% of the US population have wheat/gluten related disorders.(1)

These disorders occur on a spectrum, with celiac disease being on one end and non-celiac gluten sensitivity at the other end.

The most common gastrointestinal symptoms associated with wheat/gluten related disorders are:

  • Heartburn
  • Stomach pain
  • Bloating
  • Diarrhea
  • Constipation
  • IBS

These are just the intestinal symptoms.

Symptoms outside of the intestinal tract include fatigue, headache, joint or muscle pain, foggy mind, skin rashes and nutritional deficiencies, just to name a few. We will go over more of the symptoms later in this article.

If you are dealing with any of these symptoms, then it may be likely that you have a gluten related disorder as well.

Here are some of the most common reasons why millions of people have reactions to wheat…….

Four Reasons Why You May Have Reactions to Wheat

Wheat is composed of many different protein types (gluten included) that stimulate the immune system. High amounts of indigestible carbohydrates are also present.

Symptoms can result from an intolerance to these proteins and/or carbohydrates, which can make those of us with SIBO feel worse.

All of the following conditions are considered a spectrum of wheat/gluten related disorders:

  • Wheat allergy
  • Celiac disease
  • Non-celiac gluten sensitivity
  • Intolerance to specific fermentable carbohydrates (FODMAPs) found in wheat.

To know what is making your symptoms worse, you need to know if you have any of these conditions.


Wheat is classified as one of the top 8 food allergens, along with soy, dairy, shellfish, eggs, fish, peanuts and tree nuts.

Wheat allergy effects 0.5%-9% of the population worldwide.(2) It is most commonly seen in children. The majority of them will outgrow it before they reach adulthood.(1)

Adults are not out of the woods. A small percentage (0.4%) of adults are diagnosed with wheat allergy by their doctor.(2)

Knowing if you have wheat allergy can help you get one step closer to identifying whether or not wheat is making your SIBO worse.

Wheat allergy can cause GI symptoms and therefore make SIBO worse. IgE allergies in general are on the rise,(3) so don’t dismiss this type of wheat related disorder.

The Immune System’s Response in Wheat Allergy

It is important to know how the body responds when a wheat allergy is involved in order to help distinguish the reaction from the other wheat/gluten sensitivities.

When wheat is ingested, the immune system produces specific antibodies called immunoglobin E (IgE). These antibodies see protein in wheat as foreign invaders and they trigger cells in the body to release certain chemicals.

Eleven allergenic proteins have been identified in wheat!(4)

Symptoms to Look Out For

Immune reactions to these allergenic proteins is what produces the uncomfortable and sometimes life threatening symptoms associated with this type of allergy. Symptoms from IgE mediated reactions typically occur very soon to a few hours after eating wheat, and they include:(5)

  • Hives
  • Anaphylaxis
  • Nausea
  • Vomiting
  • Diarrhea
  • Hay fever
  • Blockage of the airway after exercising.

You may already be familiar with these types of allergic reactions. All of us have heard of someone eating a bite of shrimp and breaking out in hives or a person that almost died from eating a peanut. These are examples of IgE reactions to specific proteins found in these foods.

Just a tiny crumb of wheat or even inhaling wheat dust (which may occur while you are baking with it) can lead to reactions.

How Do I Test for Wheat Allergy?

Most adults who have an allergy to wheat know it because they have either had the allergy since childhood, or the reactions happen so quickly after eating wheat they were able to make the association.

If you are not sure, there are several methods that can be used to test for IgE food allergies. These tests include skin prick testing, serum testing for IgE antibodies and food challenges.

Each have their advantages and disadvantages.

Your allergist or healthcare practitioner can help you determine the best test for you.

Remember, even though wheat allergy isn’t as common in adults, it is still a good idea to get tested just in case. While you are at it, you can test for the other top 8 allergens as well.


Celiac disease (CD) is the next condition on the wheat/gluten intolerance spectrum. When I was trying to figure out why I was having such terrible bloating and constipation, I asked my doctor to test me for it.

I was actually disappointed when I was told that I didn’t have it. Of course, I look back now and am thankful, because it is a serious, lifelong condition. But when you are miserable, you want answers, any answers. I’m sure you have been there.

CD is an autoimmune reaction to gluten in genetically susceptible individuals. It affects approximately 1% of the US and European population and may be as high as 1.5% in the Northern European countries.(6) This equates to 1 out of 100 people suffering with this condition.

Studies vary as to whether there is a link between SIBO and CD. A review conducted in 2017 concluded that SIBO was more common in CD for those who were not responding well to a gluten free diet.(7)

I definitely feel it is worth being tested if you have the above symptoms and/or if you are suffering from one or more autoimmune diseases.

The Immune System’s Response in Celiac Disease

How is celiac disease different from wheat allergy? Remember, wheat allergy involves an IgE response to proteins found in wheat.

In celiac disease, the immune response is to gliadin in particular. Gliadin is a protein that together with glutenin, forms gluten. These proteins together are what gives bread its elastic chewiness and structure.

Without gluten, the bread just falls apart. Sound characteristic of typical gluten free foods?

Gluten (gliadin) is also found in rye and barley.

When the gliadin protein reaches the small intestine, the adaptive immune system (T-cells to be exact) see it as an enemy. It’s like the gliadin causes the immune system to overreact and shoot blindly, destroying everything in its path-which happens to be the delicate lining of the small intestine.(8) Once this happens, it is very difficult to digest and absorb nutrients.

Symptoms to Look Out For

The “classic” presentation of CD was typically diagnosed in childhood. The child would have symptoms like weight loss, diarrhea, fat malabsorption, bloating and maybe even vomiting or constipation.(9) Adults may or may not have these classic symptoms. According to the Celiac Disease Foundation, symptoms in adults are:

  • Unexplained iron-deficiency anemia
  • Fatigue
  • Bone or joint pain
  • Arthritis
  • Osteoporosis
  • Liver and gallbladder type disorders
  • Depression or anxiety
  • Tingling in hands and feet
  • Seizures or migraines
  • Missed menstrual periods
  • Infertility/recurrent miscarriages
  • Canker sores
  • Itchy skin rash.

These symptoms seem so random and unrelated, people may spend years going through the medical system trying to find answers to their symptoms. They may be told that it is just IBS or they were convinced that they were imagining their symptoms before finally getting diagnosed.

How Do I Test for Celiac Disease?

It is recommended that before you eliminate gluten from your diet, check and see if you have any of the above unexplained symptoms. If so, then talk to your healthcare practitioner about being tested for celiac disease.

You can start with a blood test to look for IgA and IgG (if deficient) autoantibodies against deamidated gliadin peptides and antitissue transglutaminase (tTg).(10)

If these are positive, then the gold standard for diagnosis is to get a biopsy from the upper part of the small intestine to look for damage to the intestinal lining.


Maybe you have been tested for celiac disease and wheat allergy and were told that you didn’t have an issue, but you know that when you eat wheat, you just don’t feel good.

Or, maybe you just don’t feel good and want to know if wheat might be causing your symptoms.

I found out in 2011 that I have a major problem with wheat. I didn’t have an allergy or celiac disease, so I was off the hook, right? That is so not the case. There are other “things” in wheat that can cause reactions.

Since then, I learned that there was actually a name for what was happening to me, it is called non-celiac gluten sensitivity (NCGS).

This condition happens when wheat ingestion causes symptoms, both in the GI tract and elsewhere in the body, BUT in the absence of wheat allergy or celiac disease.(11,12,13)

It is estimated that 6-7% of the US population have NCGS.(10) There has been a lot of debate in the medical community as to whether NCGS is real. But research is exploding in this area and for those unbelievers, the term NCGS was established by a team of experts as a medical condition in 2012.(6) And, it also has its own medical billing code (ICD-10 code), so there you go, once insurance is involved, then it’s official!

A lot of the symptoms associated with NCGS, like diarrhea, bloating, abdominal pain, constipation, and nausea are exactly what we experience with SIBO.

It is already established that wheat is linked to IBS-like symptoms.(14)

If you have SIBO and you have already ruled out wheat allergy and celiac disease, then it would be worth it to remove wheat/gluten from your diet. It could make a big difference in your symptoms.

The Immune System’s Response in NCGS

Like wheat allergy and celiac disease, the immune system is also involved in NCGS. What makes this condition different is that it does not involve an IgE immune response (like with wheat allergy) and there is no damage to the intestinal lining (like with celiac disease).

The part of the immune system that is most activated by NCGS is the innate, or non-specific arm of the immune system. Whereas in celiac disease, the adaptive immune system (T-cells) is fundamental in the development of the condition.(15) However, as research continues in this area, they are discovering that the adaptive arm of the immune system may also be involved.(16)

Many proteins in wheat can cause immune system activation in NCGS. The two most commonly reported offenders are amylase-trypsin inhibitors (ATIs) and wheat germ agglutinin.(17,18)

What I’m trying to say here is that clinical research is starting to identify that there is a measurable immune reaction in people who are sensitive to wheat/gluten, that has nothing to do with wheat allergy and celiac disease. This isn’t just a made up disorder!

Symptoms to Look Out For

It can be difficult to tell the difference between symptoms of wheat allergy, CD and NCGS. Like the other two conditions, the symptoms in NCGS can cause problems in the gastrointestinal tract as well as in other places in the body. Here are some common symptoms that are published in the literature in patients identified to have NCGS:(19)

  • Diarrhea
  • Bloating
  • Abdominal pain, constipation, nausea
  • Brain fog
  • Fibromyalgia
  • Fatigue
  • Skin rash
  • Headaches

NCGS has been an issue since the 1970’s, but most medical professionals (including dietitians) have held onto the belief that if you don’t have a wheat allergy or celiac disease, you have free reign to eat as much gluten as you want. That is farthest from the truth. It is important that this condition be identified because many people are suffering needlessly.

I have had clients in my practice with all kinds of symptoms, ranging from hives to brain fog, who were negative for wheat allergy and CD. But they had remarkable improvement in their symptoms when removing wheat. You could be one of them.

How Do I Test for NCGS?

Researchers are working hard to determine specific markers that will confirm the diagnosis of  NCGS. Some biomarkers are currently being proposed and it is only a matter of time before these reach mainstream labs.

Until that time, the best way to know if you have NCGS is to eliminate wheat/gluten for 4-6 weeks and track your improvements.

Symptoms can appear within hours or days after the ingestion of wheat. If you have NCGS, the symptoms will resolve when gluten is removed.(19)


So far, we have discussed three of the four major causes of wheat/gluten intolerance-wheat allergy, celiac disease and non-celiac gluten sensitivity. The mechanism of action for all of these conditions involves specific proteins that trigger the immune system.

But could there be something else in wheat that is causing symptoms besides protein?

Yes, there is.

FODMAPs is an acronym that stands for fermentable oligo-, di-, mono-saccharides and polyols.

Wheat, as well as rye and barley, contain high amounts of the FODMAPs called fructan/fructo-oligosaccharide (FOS) as well as galacto-oligosaccharides (GOS).(20)

Other FODMAPs commonly found in an array of different foods include excess fructose, lactose and sugar polyols.

People with SIBO have large numbers of bacteria that inhabit the small intestine. When FODMAP carbohydrates are eaten, the bacteria in the small intestine eat the carbohydrates instead. This can cause uncomfortable abdominal distension within an hour to a few hours of ingestion.

My clients will tell me “my stomach is so big, I look like I’m 6 months pregnant!”

Could it be the FODMAP carbohydrates in the wheat that is causing the bloating?

Removing FODMAPs from the diet can change the number, composition and function of the bacteria in the intestinal tract.(24) This can make a big improvement in SIBO symptoms.

See 6 Tips to Starting the FODMAPs Diet without Feeling Overwhelmed for more information about the FODMAPs diet.

The Body’s Response to FODMAP Sensitivity

It’s the carbohydrates this time, not the protein!

What do I mean by that? Symptoms occur via a totally different mechanism than what happens with the other 3 conditions on the gluten intolerance spectrum. It is carbohydrate malabsorption that causes the symptoms, not immune reactions to protein. So what happens in the body?

FODMAP carbohydrates are poorly absorbed in the small intestine and therefore hang out where they shouldn’t, drawing a lot of water into the intestinal tract. This can cause diarrhea and stomach pain. In addition, the bacteria and other creatures living in the small and large intestine ferment these carbohydrates before we can digest them, leading to large amounts of uncomfortable gas and bloating.

Some researchers believe that it is the FODMAPs in wheat and not the proteins (as described above) that cause the GI symptoms.(20)

I think it could be both.

Symptoms to Look Out For

Symptoms related to FODMAP intolerance mainly occurs in the gastrointestinal tract and seem to be more intense for people with IBS. This is because people with IBS are more sensitive to pain in their intestinal tract.

Symptoms of FODMAP intolerance published in the literature include:

  • Diarrhea
  • Bloating
  • Increased flatulence/gas
  • Abdominal pain,(21)
  • Heartburn
  • Nausea
  • Fatigue (22)

Many of my SIBO patients have FODMAP intolerance and it can really make them miserable. When I suggest that my clients follow the low FODMAPs diet, many of them react in utter dismay when they see that they will also have to eliminate wheat. As you can see, wheat has many issues!

How Do I Test for FODMAP Intolerance?

It sure would be nice to just take a test to figure out if you have FODMAPs intolerance. And, as a matter of fact, there are a few FODMAPs that you can actually test for. These include lactose, fructose and sorbitol.(23)

When these carbohydrates are ingested, if they are not absorbed, then the bacteria in the intestinal tract will consume them and produce hydrogen as a byproduct. The hydrogen will be expelled through the lungs and can be measured using a breath hydrogen test.

Unfortunately, there is no test to determine if you have an intolerance to the FODMAPs commonly found in wheat.

The only way to know if your symptoms are caused by a FODMAP intolerance is to eliminate them for your diet and then conduct a rechallenge (again, see 6 Tips to Starting the FODMAPs Diet without Feeling Overwhelmed )

Wheat/Gluten Can Make Your SIBO Symptoms Worse

As you can see, wheat isn’t as innocent as we would like to think.

I have had clients with SIBO react to wheat because they had an allergy, CD, NCGS and/or reactions from the FODMAPs in wheat.

All of these reactions can make your SIBO worse and it is important to rule them out to help with your SIBO symptoms.

If you need help with determining where you are on the spectrum of wheat/gluten intolerance, then please click here for a free, 30 minute SIBO Troubleshooting Consultation, where we will go through your diet and symptom history.



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