Over the last year or so, we’ve seen a glut of stories in the popular media suggesting that non-celiac gluten sensitivity (i.e. people that react to gluten but do not have celiac disease) is a myth:
- Science Proves Gluten Sensitivity Isn’t Real, People Are Just Whiners
- The Science Is In — Why Gluten Sensitivity Is Probably Fake
- Gluten Intolerance May Be Completely Fake: Study
- Non-Celiac Gluten Sensitivity May Not Exist
- Gluten Intolerance May Not Exist
Even late-night TV host Jimmy Kimmel weighed in with a segment that got a lot of attention in both popular and social media.
Just after these stories were published, I wrote an article (“Is Gluten Sensitivity Real?”) showing how the authors grossly misinterpreted and misrepresented the research they claimed to be reviewing.
You can read my article to get the details, but here’s the takeaway: the study those stories were based on in no way disproved the existence of non-celiac gluten sensitivity (NCGS), nor did it overturn the large body of evidence that links NCGS to a variety of health problems ranging from type 1 diabetes, to allergies, to schizophrenia, to autism spectrum disorders. (1, 2, 3, 4)
Research shows gluten intolerance is real—and “science journalists” are clueless.
What struck me about those stories—aside from how embarrassing they are as examples of so-called “science journalism”—is how eager the general public seems to be to prove that gluten intolerance is an imaginary or fake condition. I’m not exactly sure why this is. Maybe it’s because gluten-containing foods and beverages like bread and beer have played such a central role in our culture for thousands of years. Or perhaps people simply distrust anything they perceive to be inauthentic or “faddish”.
What the Science Really Says about Gluten Intolerance
While I can relate to an aversion to fads (don’t get me started on Hipsters), and the gluten-free diet could in some ways be described as a fad, the consensus in the scientific literature is that non-celiac gluten sensitivity is a bona-fide condition with numerous—and potentially serious—manifestations. According to a recent review paper called “Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders”:
…a rapidly increasing number of papers have been published by many independent groups, confirming that GS [non-celiac gluten sensitivity] should be included in the spectrum of gluten-related disorders. (5)
Observational studies have linked gluten intolerance with a shockingly diverse range of symptoms and conditions, including:
- Irritable bowel syndrome (6)
- Fibromyalgia (7)
- Dermatitis and other skin conditions (8)
- Multiple sclerosis (9)
- Peripheral neuropathy, myopathy, and other neurological disorders (10)
- Schizophrenia (11)
- Depression (12)
- Attention deficit hyperactivity disorder (13)
- Ataxia (14)
- Type 1 diabetes (15)
- Autism spectrum disorders (16)
- Ménière disease (17)
- Endometriosis (18)
- Insulin resistance and inflammation (19)
I could go on, but I think you get the point. If the authors of the “gluten intolerance is fake” articles had spent even five minutes examining the research, they would have seen numerous papers supporting the existence of non-celiac gluten sensitivity.
And they aren’t just observational studies; some of them are randomized clinical trials (RCTs), which are considered to be the gold standard of medical evidence. In fact, just last month, a new RCT was published that validated NCGS as a legitimate condition. (20) This was a double-blind, placebo-controlled trial, and it had the additional benefit of a crossover design (which I’ll describe below).
The researchers enrolled 61 participants without celiac disease or wheat allergy, but with self-identified gluten intolerance. Subjects were then randomly assigned to two groups; one was given a capsule with 4.4 grams per day of gluten (roughly the amount in two slices of white bread), and the other was given a placebo capsule containing only rice starch. After one week of a gluten-free diet, participants then “crossed over” into the other group (those that received the gluten capsules during the first round got rice starch, and vice versa). Crossover studies are advantageous because each crossover participant serves as his or her own control, which reduces the likelihood of confounding variables influencing the results.
As you can see, despite the rash and uninformed claims you may have seen in the popular media, gluten intolerance is indeed a real condition and not just a figment of the imagination. (Of course, if you happen to be one of the people that suffers from gluten intolerance, you didn’t need me—or any study—to tell you that!)
Why Gluten Intolerance Is Likely More Common Than Currently Estimated
Estimates for the prevalence of NCGS vary widely, ranging from 0.5% on the low end to 13% or higher on the high end. (21) However, there are three reasons why I believe NCGS is much more common than currently estimated:
- Current commercially-available tests (with one or two notable exceptions) are extremely limited and miss many people with gluten intolerance. Most conventional tests for gluten intolerance only screen for antibodies to a specific fraction of the gluten protein, alpha-gliadin. But we now know that people can (and do) react to several other components of wheat and gluten—including other epitopes of gliadin (beta, gamma, omega), glutenin, WGA and deamidated gliadin. I reviewed this subject in more detail in my previous article, 50 Shades of Gluten Intolerance.
- Even the best serological (blood) testing is not 100 percent accurate. An elimination/provocation challenge, where gluten is removed from the diet for 60–90 days, and then reintroduced, is still the gold standard for diagnosing gluten intolerance. However, many physicians are unaware of this and thus do not suggest it to their patients.
- Many physicians and patients only suspect—and therefore test for—gluten intolerance when digestive symptoms are present. However, both gluten intolerance and celiac disease can present without any gut symptoms, and only extra-intestinal symptoms like ataxia, schizophrenia, dermatitis, or neuropathy. In fact, the majority of patients with neurological manifestations of gluten sensitivity have no gastrointestinal symptoms! (22) In the case of celiac disease, which has been better studied than NCGS so far, about 30 percent of newly diagnosed patients do not have gut symptoms, and for every new case that is diagnosed, there are 6.4 cases that are undiagnosed—the majority of which are atypical or “silent” forms without gut symptoms. (23, 24)
When you put all of this together, it is almost certain that NCGS is far more prevalent than the current estimates suggest it is.
Is Removing Gluten from Your Diet Dangerous?
The most glaring problem with this argument is the simple fact that humans have only been consuming gluten for the past 11,000 years or so, which represents a tiny fraction of our evolutionary history. That’s about 367 generations, compared to the 66,000 generations we evolved in an environment without gluten or cereal grains.
The second problem with this argument is that even whole grains are not very nutrient dense. In fact, when compared with other foods like organ meats, fish, meats, vegetables, and fruits, whole grains are at the bottom of the list. (25) As you’d suspect, refined grains (like flour) are even lower. This is significant because 85 percent of the grain consumed in the US is in the highly refined form, and refined flour accounts for approximately 20 percent of calories consumed by the average American. (26)
Finally, studies that have assessed the nutritional quality of gluten-free diets have, not surprisingly, found that they are not lacking in any necessary nutrient. (27) If anything, people on a gluten-free diet are more likely to increase their intake of essential nutrients, especially if they replace breads and other flour products with whole foods (rather than with gluten-free flour alternatives).
In my book, The Paleo Cure (previously published as Your Personal Paleo Code), I argued that there are three categories of response to gluten:
- Non-celiac gluten sensitivity, aka “gluten intolerance”
- Celiac disease
I don’t believe that gluten is responsible for all chronic illness in all people, as some have seemed to suggest. But I think the research clearly supports the existence non-celiac gluten sensitivity, and if anything, it is significantly under-diagnosed.
One of my favorite alternate titles I considered for this article was “Gluten Intolerance Is Not Fake, But Science Journalists Are”. It was disheartening to see so many sensational and poorly researched news stories making the claim that gluten intolerance is not a legitimate condition. Not only were those authors wrong, they were irresponsible and failed to do even the most basic background research about the subject they were writing about. This should be yet another reminder to take what you read in the popular health media with a large grain of salt.