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Research Suggests Non-Celiac Gluten Sensitivity is Uncommon; Learn What Most People May Have

Home / Research News / Research Suggests Non-Celiac Gluten Sensitivity is Uncommon; Learn What Most People May Have
An older woman sits at a kitchen table holding her stomach and wincing in pain while holding a sandwich. A bowl of salad, a glass of water, and a plate with pills are on the table in front of her.

By Bailey Arman

A literature review published in The Lancet suggests that while 10% of the global population reports reacting to gluten, most of these people probably aren’t sensitive to gluten. When compiling data from multiple clinical studies, just 16–30% of people who report gluten intolerance had symptoms truly triggered by gluten. 

So what could be causing trouble for the up to 84% of folks who believe they react to gluten, but probably don’t? And why haven’t they received a proper diagnosis? 

What is Non-Celiac Gluten Sensitivity?

Many people who say they have a “gluten intolerance” report symptoms after eating gluten, such as gas, diarrhea, bloating, headache and fatigue. Although commonly called “gluten intolerance,” the more accurate medical term for this is “non-celiac gluten sensitivity,” or NCGS for short. 

NCGS is separate from celiac disease. People with celiac disease, an autoimmune condition, suffer damage to the intestine when they eat gluten, a protein found in wheat, barley, and rye, so they have to be strictly gluten-free for their whole lives. Testing for celiac disease is as simple as a blood draw.

Unfortunately, no such test exists for NCGS; instead, it’s diagnosed by exclusion. This means that doctors only diagnose a person with NCGS after ruling out all other conditions that could cause similar symptoms.

Definitions

  • Gluten: a protein found in wheat, barley, and rye.
  • Celiac disease (CD): an autoimmune disease. When someone with CD eats gluten, their immune system attacks the small intestine. Symptoms vary, but everyone with CD has measurable organ damage.
  • Non-celiac gluten sensitivity (NCGS): Sometimes called a “gluten sensitivity” or “gluten intolerance,” people with NCGS react to gluten, but do not have the same antibodies or internal damage seen with CD.
  • Diagnosis of exclusion: Some illnesses can’t be identified with a specific test, like a throat swab or blood draw. Instead, doctors test for and rule out all other possible causes. This is called “diagnosis of exclusion.” NCGS is usually only diagnosed after celiac disease, wheat allergy, and other conditions have been ruled out.
  • FODMAPs: A type of carbohydrate. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.
  • Placebo: a fake treatment without any medication. For example, a pill that doesn’t contain any drug, just sugar.
  • Nocebo effect: a phenomenon where a person expects to feel sick after ingesting something like a pill, and does feel sick—even when there was nothing in the pill that could’ve caused it. 
  • Gut-brain connection: The strong communication system between the digestive tract and the neurological system.

Why it’s Probably Not NCGS

The study authors reviewed 58 research studies of gluten reactions from the past few decades and summarized key findings and how well the studies were done. They did not conduct new experiments, and they did not look at studies of people diagnosed with celiac disease, gluten ataxia, or other neurological complications.

The review focused primarily on experiments using placebos. In these experiments, participants who claimed gluten intolerance were asked to eat food they were told contained gluten, but was actually gluten-free. Many of these participants reported symptoms after eating it even though the food was gluten-free. This indicates these folks may be reacting to something other than gluten.

So what else could that be?

What Conditions to Watch For

The researchers suggest that many cases of gluten sensitivity may actually be a FODMAP sensitivity, irritable bowel syndrome (IBS), or nocebo effect.

FODMAP Fake-Out

The research suggests that many people who think they’re sensitive to gluten may actually be sensitive to FODMAPs, a type of carbohydrate. Notably, grains that contain gluten, like wheat, barley and rye, also contain high levels of FODMAPs. So these patients could very well be having a reaction to eating foods with gluten, but crucially, it’s not the gluten causing the issue. If that’s the case, a gluten-free diet won’t resolve the issue—instead, these folks may benefit more from a low FODMAP diet.

Is it IBS?

Symptoms mentioned in the studies—cramping, abdominal pain, bloating, gas, diarrhea and constipation—are also common in irritable bowel syndrome (IBS), a chronic condition that affects the large intestine. Different foods trigger IBS symptoms in different patients, but gluten and wheat are common culprits. 

IBS is also diagnosed by exclusion, the same as NCGS. There is no specific test for either condition. Since IBS symptoms overlap with NCGS, the authors say it is difficult to tell the two conditions apart—some researchers have gone so far as to suggest that NCGS is not a separate condition, but rather a type of IBS triggered only by gluten.

Nocebo in a Nutshell

“The nocebo effect” is a phenomenon where a person expects to feel bad after eating something like a pill, and does feel bad—even when there was nothing in the pill that could’ve caused it. 

The brain is powerful, and in recent decades, research has revealed just how closely the gut and the brain communicate. When one end of the equation isn’t feeling well, the other suffers, and vice-versa. 

The study authors suggest some people who report a reaction to gluten could be experiencing the nocebo effect. Several of the studies reviewed support this claim: participants who were told they would be eating gluten reported symptoms even though they received a placebo and hadn’t actually consumed any gluten. 

That doesn’t mean the symptoms didn’t happen, it just means that gluten probably isn’t causing their symptoms, and possibly FODMAPs aren’t either. It could simply be the power of suggestion.

Why This Matters

Everyone deserves a timely and accurate diagnosis and an effective treatment so they can start feeling better. While the gluten-free diet can help people with celiac disease and NCGS feel better, it can also be restrictive, expensive, and unhealthy. If a person doesn’t need to be on it—or, more importantly, if there is a different treatment that will work better for them—they deserve to know.

Struggling With Symptoms?

Your symptoms and concerns are valid. Although understudied, NCGS can have serious long-term implications—Beyond Celiac-funded research has found that brain damage is possible in both people with celiac disease and other gluten-related disorders. 

That being said, the study authors and Beyond Celiac advise against self-diagnosing any condition. As always, Beyond Celiac encourages anyone experiencing symptoms to work with their healthcare team to identify a cause before going gluten-free or making major changes to their diet. 

Unfortunately, you can’t be tested for celiac disease if you’re already gluten-free, so it’s always best to get tested for celiac before going gluten-free—it’s as simple as a blood test! Fill out our symptoms checklist to get the conversation started with your doctor.

The study authors suggest that suspected NCGS should be managed by following a gluten-free diet under the care of a dietitian who could help rule out effects from FODMAPs. They also suggest that, given the number of studies showing a nocebo effect, cognitive behavioral therapy could also be used to treat those with suspected NCGS.

For a list of clinics in the USA specializing in celiac disease and the gluten-free diet, visit our Find Specialty Care page.

Limitations

The article discussed was a literature review, which means the authors looked at many NCGS research articles and summarized key findings. However, there aren’t universal standards for diagnosing NCGS, distributing gluten, or dosing gluten, so each study reviewed handled these logistics differently. This is a major challenge to conducting NCGS research, because wheat contains both gluten and FODMAPs and both can cause similar symptoms; it’s important to be able to separate the two when conducting experiments so researchers can be sure which is causing symptoms. Receiving both gluten and FODMAPs at once—which happened in many studies—can limit the conclusions that can be drawn. 

As a result of these limitations and the overall conclusions of the study, the study authors proposed guidelines for research, diagnosis, and management of NCGS. More standardized research is needed to better identify the parameters of NCGS, its causes, and potential diagnostic tests.

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