Does non-celiac gluten sensitivity really exist?

When Linda Kerr’s son’s growth flatlined, a doctor suggested the teen might benefit from a gluten-free diet. In support, she tried the diet with him. Her son eventually decided he wasn’t going to follow it, but it did have an unexpected effect: after about a month, Kerr herself found her health improved. “I’d been struggling all of my life with irritable bowel syndrome [a chronic condition that causes cramping, pain and gas],” she says. “I felt so much better following a gluten-free diet.” The retired dietitian, who lives in Westerose, Alberta, has been on a gluten-restricted diet ever since. “I find I can have one serving of gluten a day,” she says. She considers herself gluten sensitive.

In the 15 years since she’s been on this diet, gluten-free foods have moved from the specialty aisles of health-food stores to mainstream grocery stores like Loblaws, Costco and Walmart. Restaurants now highlight gluten-free menu options, and gluten-free bakeries have popped up to offer cakes, cookies and bread.

These companies are targeting a trend: Gluten-free foods are the fastest growing food intolerance category in North America. Market-research firm Packaged Facts estimated the Canadian gluten-free market was worth over $450 million in 2012, rising 27% a year between 2008 and 2012. And a recent survey of U.S. dietitians predicted anti-wheat sentiment would be the largest consumer trend of 2014.

Related articles

Before the recent interest in gluten sensitivity, two different types of people avoided gluten, a protein found in wheat, barley and rye, as well as many processed foods. The first, and by far the most common, were people with celiac disease. The disorder, which is part autoimmune and part food allergy, revolves around intestinal inflammation in response to gluten. It causes a broad range of symptoms, including diarrhea, weight loss, anemia and osteoporosis, which can also be very mild and non-specific. Avoiding gluten is recognized as an effective treatment. The second group who avoided gluten had an allergy to wheat itself, which causes a typical antibody response and familiar allergic reaction, such as hives, rash or even anaphylaxis.

But now many more people are choosing not to eat gluten, believing they have non-celiac gluten sensitivity. Although they don’t have celiac disease, they feel better when not eating wheat, reporting less abdominal pain, gas, headaches and fatigue.

Researchers have been studying this phenomenon of non-celiac gluten sensitivity, but their results have been mixed, causing some to question if it even exists. What does the science say about this new disorder – and the diet that comes with it?

Going against the grains

The wheat-bucking trend is being fuelled by celebrities like Gwyneth Paltrow and Miley Cyrus, who Tweeted, “It’s not about weight it’s about health. Gluten is cr-pppp anyway!” The diet launched off the low-carb craze of the late-’90s, with new books like Wheat Belly and Grain Brain promising that giving up gluten was the path to more energy, clearer thinking and, of course, weight loss.

The science doesn’t support that idea – a 2006 study found that 81% of people with celiac disease on gluten-free diets gained weight over two years, even those who were overweight to start with. In addition, adherents may not get enough iron and B vitamins, which are found in fortified flours but not most gluten-free ones. And people who follow the diet are often not eating enough calcium and fibre.

“I think that perhaps people are embracing this diet a little bit too enthusiastically, and they are basing that choice not on scientifically sound data, but on recommendations that they find on the internet, or on what a celebrity is doing,” says Elena Verdu, an associate professor at McMaster University and Canada Research Chair in inflammation, microbiota and nutrition.

The popularity can also lead to a health halo effect for even casual shoppers. While marketers can’t make explicit health claims, merely putting “gluten-free” on a package can mislead consumers into thinking that a box of muffins or sugary cereal is healthy.

But while there’s nothing inherently wrong with gluten, there is some support for the idea of gluten intolerance. The phenomenon was defined in a 2012 BMJ paper as “cases of gluten reactions in which neither allergic nor autoimmune mechanisms can be identified” – when the person doesn’t have celiac disease or a wheat allergy, but seems to have an adverse reaction to gluten. To know gluten is causing their symptoms, people often do a trial period where they go off gluten, then resume eating it. Many feel better when they’re off of it.

Beyond those personal stories, the science is muddy. A 2011 study by Jessica Biesiekierski and colleagues offered hope that non-celiac gluten sensitivity existed. It was inspired by those cases, says Biesiekiersk. “There were a lot of people [who had tested negative for celiac disease] coming to the gastroenterology clinic believing that gluten was a trigger for their IBS-type symptoms,” she says.

The researchers ran a randomized, double-blind study with 34 patients who had IBS and said they felt worse after eating gluten. They found that within a week, those eating gluten had significantly more symptoms. “We were quite surprised at those results – we didn’t actually expect it to be real,” Biesiekierski says.

But a follow up study by Biesiekierski’s team, published in Gastroenterology in 2013, found just the opposite. This time, they gave every participant a high-gluten, low-gluten and placebo phase. They also put everyone on a background diet, called low-FODMAPs, to minimize IBS symptoms.

The results were also surprising: they found that there was no difference between the three phases. “In fact, people got more symptoms during the placebo week,” says Biesiekierski, though a parallel study did find the participants had lower levels of depressive feelings when they weren’t eating gluten. In an accompanying piece in Gastroenterology, Rohini Vagna and Daniel Leffler, from the Beth Israel Deaconess Medical Center’s Celiac Centre in Boston, wrote: “Unfortunately, the [study] raises more questions than it answers. Indeed, the study calls into question the very existence of [non-celiac gluten sensitivity].”

Biesiekierski herself has doubts. “There’s a lot of mixed evidence: it might exist, but we don’t know for sure yet,” she says. A 2013 review of the research, co-authored by Biesiekierski, concluded “the evidence base for gluten as a trigger of symptoms in patients without celiac disease (so-called ‘non-celiac gluten sensitivity’ or NCGS) is limited.”

So why do people feel better when they stop eating gluten? Some may be have undiagnosed celiac disease – it’s underdiagnosed, though there has been a growth in awareness about it. In addition, increasing numbers of people have the disease – it’s currently around 1 in 133. For people with celiac disease, a strict-gluten free diet results in dramatic health improvements, which often begin within days.

It’s crucial for patients to rule out a celiac diagnosis before trying a gluten-free diet, since they need to be eating gluten at the time for the celiac test to work. And it can be difficult to rule out celiac completely. “We know that there is celiac disease that exists without the strict definition of the biopsy, there are people with celiac disease that have some mild inflammation. Depending on the number of biopsies, it can be missed,” says Alaa Rostom, chief of gastroenterology at The Ottawa Hospital. It’s also important to test for a wheat allergy.

The sensitive types

But that still leaves a group of people who don’t have celiac disease and report they feel better when not eating gluten. “It’s not just GI symptoms: often they’ll talk also about headache, a foggy brain, dizziness,” says Rostom.

These people may be experiencing the nocebo effect, where you believe something will make you feel sick, and then it does as a result. “There is so much bad press about the wheat containing diet that many patients think or believe that their symptoms are really caused by gluten, because they read it all day in the newspapers,” says Verdu.

Or perhaps they’re reacting to something else in the wheat. Biesiekierski’s team put all their participants on a low-FODMAPs diet, which doesn’t restrict gluten. The diet, which was developed at Monash University in Australia, improves IBS symptoms in about 75% of patients. And all of the participants in Biesiekierski’s latest gluten study had fewer symptoms on the baseline low-FODMAP diet. Fructan, one of the FODMAPs to avoid, is also found in wheat. By going gluten-free, people might be lowering their FODMAP intake without knowing it.

“The problem with the evidence is really what you can attribute the effects to,” says Peter Gibson, a co-author on both Biesiekierski studies. He adds that while the latter study didn’t prove gluten sensitivity isn’t real, “what we can say is that it’s very, very uncommon.”

Complicating all of these studies is the fact that, unlike for celiac disease, there’s no biomarker or test for gluten sensitivity, so finding the right groups to research is difficult. “It’s very important to try to find a marker, to say that this subgroup of people are going to benefit from a gluten-free diet,” says Verdu. The mechanism behind it is also still unknown.

“The bottom line is that I don’t think that the studies are of sufficient quality to actually say that this condition absolutely does or doesn’t exist,” says Rostom. In the absence of evidence, his answer, like many gastroenterologists’, is that if his patients feel better off gluten, and other issues have been ruled out, he’s fine with them being on the diet. “It’s pragmatic,” he explains.

Part of that is driven out of empathy. IBS is a common complaint, and there are limited treatments for it.

“There is a group of people [with IBS] whose symptoms are a little bit more dramatic, and their response is more intense. They are very frustrated, so they often go out and try a whole bunch of things. You can sympathize with them when they do try these various diets,” says Rostom. “But I also hear from people that say every time I eat tomatoes, or cucumbers, I have problems. If it was clear cut, it would be a lot easier.”

The comments section is closed.

  • Eva says:

    Writing off people who experience symptoms as having the nocebo effect does not appear to me to be scientific at all.
    I know too many people who have autoimmune diseases who do better when they do not consume gluten. It is true it may be something other than gluten such as fructans but for Drs to tell the person experiencing symptoms it is in their heads is

  • G Fresh says:

    This study seems to show that non Celiac gluten intolerance actually does exist:

    “”The majority of non-celiac gluten sensitivity patients (93.2%) showed the disappearance of anti-gliadin antibodies of IgG class after 6 months of gluten-free diet; in contrast, 16/40 (40%) of celiac patients displayed the persistence of these antibodies after gluten withdrawal. In non-celiac gluten sensitivity patients anti-gliadin antibodies IgG persistence after gluten withdrawal was significantly correlated with the low compliance to gluten-free diet and a mild clinical response.

    Anti-gliadin antibodies of the IgG class disappear in patients with non-celiac gluten sensitivity reflecting a strict compliance to the gluten-free diet and a good clinical response to gluten withdrawal.”

  • Mia says:

    I suffered all through childhood and my 20’s with horrible bloating, constipation, skin problems and intense fatigue. Doctors were useless, telling me to eat more bran which made me worse. Going gluten free in my 30’s changed a lot of that. I went from painful 7 day constipation to daily easy movements in one week just from removing gluten from my diet and could final “pass” gas. Many people suffer for a long time with no help. My mother with IBS also improved significantly with a gluten free diet. When we eat gluten the problems return. There is so little research because there is no funding for research in this area. I tested negative for celiac.

  • GulAlp says:


    I don’t think it happens because it is trendy, I think it becomes trendy because it is real. There might be people who are severely affected by psychological reasons but this doesn’t mean that there are people who are actually living with a real problem, physiological problem everyday. Please do not fool those people, or damage their credibility. I am not emotional person, and I really doesn’t complain much. But when I had a real problem people thought it wasn’t real. Because of this approach. I must say I didn’t find it very nice personally.

    I had bloating belly, cramps, and gas and migraine headaches for many years, and seven-eight years ago I started to have slight dizziness which increased in time to a level that I wasn’t able to function properly during the day, and finally numbness on my legs and arms added to these. With the last one I alarmed because the brain cancer of a close friend of mine started like that. I had accepted my intestine problems and dizziness as a regular part of my life. I went to a doctor and she said it was psychological because I was under stress. I was sometime under stress and sometimes not, but I had the problems always. But she was decided and didn’t even give me a celiac test, which actually fit my symptoms that time.

    In that point I had no clue about celiac disease or non-celiac gluten sensitivity, but I though these might be an allergic reaction. So, I decided to experiment on myself. First I cut highly allergic food like sea food, nuts, berries etc. for three months, had no improvement. Then I cut all diary for three months again no improvement on the symptoms. Meanwhile I educated myself on allergies and read about symptoms. Close to end of my diary experiment I read about gluten first time in my life. And decided to experiment with that for next three months. I needed only three days to get rid of all symptoms at once. Since then I am gluten free, able to function again and happier.

    I am not a scientist or an expert, but as you can see I cold bloodily experimented on my self without any trendy affects. Medicine might not know how to find this problem with blood or urine tests yet, but I think it is very real and it is not psychological. They should just accept the reality of the problem and find a way to look harder.


  • Ed Labossiere says:

    May I refer you to CBC’s “The Nature of Things”, “Brain Magic: The Power of Placebos”. Another example of a disease sydrome is Lyme Disease. Like GI, very few people actually have the disease but many preseent with the symptoms. Mainstream medicine treats the body like a machine when actually age-old medical treatments dealt with the mind-body connection. I have seen a number of people “cured” of pain issues and various symptoms by applying Dr. John E. Sarno’s approach (TMS/PPD).
    Caution is advised but the symptoms of disease and discomfort are real, no matter what the root cause may be.

  • Ed Labossiere says:

    Good day,
    The answer to this question is an unequivocal yes. It is my view that the presentation of symptoms of intolerance is related to the stress levels that people experience, both conscious and unconscious. Russell Baker, columnist for the Miami Herald, wrote a piece many years ago. “Where have all the ulcers gone?” The main point was that when it become common knowledge that most cases of ulcers were stress-related other syndromes started to manifest themselves, “bad” backs, high blood pressure, anxiety attacks, migraines and the like.
    I will refer you to the theory and practice of treating pain sydromes developed by Dr.John E. Sarno of New York. It is called TMS/PPD.
    Lucy made an observation at school. She said the little boy next to her cried a lot at school today so I tried to help him. I slapped him on the arm. There is nothing like a little physical pain to take our minds off psychological problems.
    It is extremely hard to accept that adjustment issues lead to physical symptoms. I don’t understand why modern medicine does not get this. Many medical students present with the symptoms of the diseases they are studying. The mind is powerful and the pain is real even if the issues are psychological. Witness phantom limb pain syndrome.
    Many reseachers are looking into the Lyme disease sydrome as a manifestation of the same sort of thing. A final reference which is an easy-read is Dr. Mark Sopher’s “To Be or Not to Be…Pain Free”
    Ed Labossiere (Winnipeg)

  • Joan says:

    In the late 1990s, before the current gluten-free craze, and when I was in my mid-30s, I went to see a naturopath after a few years of almost daily headaches, abdominal bloating, constipation, muscle aches, and a generalized feeling of being unwell almost every day. She put me on an elimination diet of fruit, vegetables, rice. My symptoms got worse for a week and then gradually improved to the point that all symptoms disappeared.

    %featured%It took me a long time to accept my wheat sensitivity. I was embarrassed at first and told almost no one. %featured%I remember one week staying at a friend’s who did not know of my wheat sensitivity and I ate wheat daily. I was miserable again. That was a turning point for me, and I have now just accepted that I can eat very limited amounts of wheat. It is much easier now than it was in the past, with the variety of gluten free products available. I am able to eat other grains with gluten, like spelt and kamut, without effect.

    For what it is worth, the naturopath who diagnosed this was trained in Europe and had only been in Canada a few years. She said she didn’t see the wheat sensitivity in Europe like she did here, and wondered if something had happened to the digestibility of North American wheat during the intensive breeding of the plant during the 20th century.

    I know – this is just another testimonial that doesn’t count as evidence. I do appreciate Rostom’s perspective that the studies are not of sufficient quality to say one way or another. I do wonder if my experience, that my symptoms initially got worse after the introduction of a gluten-free diet, has any bearing on the contradictory research results.

  • cubic zirconia libya says:

    Awesome post .i hope everybody will like your post

  • Carrie says:

    FYI “uncommon” and “limited” results/proof may be because it’s part of a rare disorder which has a very small worldwide patient base. Testing mast cells in gastrointestinal system may be a key but the tests seem to need refinement, or new testing discovered, to reliably offer consistent proof or results for all individuals.

    Please read and review literature – medical and patient – on mastocytosis, mast cell activation, and mast cells impact on gastrointestinal system.


Vanessa Milne


Vanessa is a freelance health journalist and a form staff writer with Healthy Debate

Andreas Laupacis

Editor-in-chief Emeritus

Andreas founded Healthy Debate in 2011. He is currently the editor-in-chief of the Canadian Medical Association Journal (CMAJ)

Verna Yiu


Verna is the President and CEO at Alberta Health Services.

Republish this article

Republish this article on your website under the creative commons licence.

Learn more