Aug 06 2013

Gluten Free Defined

Gluten is the new food boogeyman for those who want to blame their ills on one simple external factor. The real story of gluten is complex – it is a real problem for some people. The recent explosion of the gluten-free fad has motivated the FDA to establish guidelines for labeling food products as having no gluten. The guidelines were actually proposed during the Bush administration, but it took until now to review the relevant scientific evidence to know where to set the limits.

According to the new regulations:

In addition to limiting the unavoidable presence of gluten to less than 20 ppm, FDA will allow manufacturers to label a food “gluten-free” if the food does not contain any of the following:

– an ingredient that is any type of wheat, rye, barley, or crossbreeds of these grains
– an ingredient derived from these grains and that has not been processed to remove gluten
– an ingredient derived from these grains and that has been processed to remove gluten, if it results in the food containing 20 or more parts per million (ppm) gluten

Foods such as bottled spring water, fruits and vegetables, and eggs can also be labeled “gluten-free” if they inherently don’t have any gluten.

What Is Gluten?

I think the definitive satire on this is from the recent movie, This Is the End. Seth Rogen (playing himself) announces to his friend that he is now eating gluten-free, but when asked what gluten is he clearly has no idea. He says it is anything bad in food. Of course in the next scene he is downing a giant hamburger.

Gluten (meaning “glue”) is a protein found in wheat, barley, and rye. It is composed of two proteins, gliadin and glutenin, which give dough its elasticity and bread its sponginess. Wheat, barley and rye are major crops and therefore gluten is present in many foods – most breads, pasta, and many processed foods.

Meat, dairy, water, fruits and vegetables do not contain any gluten. It’s interesting that the FDA will allow these foods to be labeled gluten-free also. This is a classic example of true but misleading. If a bottle of water is labeled “gluten-free” will this lead some consumers to believe that water not labeled gluten-free might have gluten (why else would they bother to label it “gluten-free”)? Will this lead to a “gluten-free” marketing arms race among food producers?

Celiac Disease and Gluten Sensitivity

Celiac disease is a non-controversial condition in which people have a severe auto-immune reaction to gluten. They have antibodies against gliadin which causes inflammation in their intestines, leading to bloating, diarrhea, nausea, and other symptoms. The reaction to even a tiny amount of gluten can be severe. About 3 million Americans have celiac disease, or 1 in 100 people.

This with celiac disease need to have a diet as free of gluten as possible. You might think that the recent gluten-free fad would be a boon to those with celiac disease, increasing their food choices. However, the lack of regulation has lead to the flooding of the market with products labeled gluten-free that still have some gluten – too much for those with celiac disease. For them the new regulations are clearly necessary.

There is also a highly controversial condition known as non-celiac gluten sensitivity (NCGS) – these are people without celiac disease who believe that gluten causes symptoms of bloating, fatigue, and irritable bowel syndrome symptoms. They do not have antibodies to gliadin.

While clinical anecdotal experience makes it seem like the gluten-free fad is a big thing, the only study I could find estimating its prevalence found that about 0.5% of those surveyed without celiac disease are adhering to a gluten-free diet (that is half the number of those with celiac disease).

NCGS remains controversial because the data so far is preliminary and conflicting. Of the two most recent studies of those with alleged NCGS who were blindly challenged with gluten vs placebo, one study showed no affect and the other did find an effect (both studies were small). Reviews of the evidence are similarly split.

What I think is likely is that there are a number of conditions that are being lumped into the NCGS basket, because it is a high profile diagnosis. These other conditions probably include mild celiac disease that is not being diagnosed, irritable bowel syndrome, wheat allergies, and perhaps other disorders such as chronic anxiety.

There may also be a separate entity of NCGS, but this has not been established either with direct clinical evidence or by finding an underlying mechanism or disease markers.

To establish a new disease it is necessary to have a clear clinical syndrome, with diagnostic features. Migraine is an excellent example of this – there are no markers or diagnostic tests, but the clinical features can be classic and definitive.

Or you need to have a clear biological process, with some laboratory test that indicates the disease process (like antibodies to gliadin).

I am always suspicious of new syndromes that lack both of these things – there are no specific signs or symptoms and no specific biomarkers. NCGS falls into this category. It would therefore not surprise me if NCGS turned out not to exist.

Alternatively it may exist, but only is a subset of those self-diagnosed with the disorder. Overdiagnosis is common with syndromes that lack specific features, especially when there is a high public awareness of them (how would there not be?).


The new FDA regulations (which will be enforced in one year) were absolutely necessary for those who have celiac disease. The downside, however, is that they may contribute to the recent fad in the NCGS diagnosis, which remains scientifically controversial.

What we now need are large definite double-blind trials to clearly establish what percentage of those with self-identified NCGS are actually sensitive to gluten. This won’t make the public controversy go away, but we do have to resolve the genuine scientific controversy before we can hope to educate the public.

I also have to emphasize that doubting the NCGS diagnosis does not represent a lack of compassion for sufferers, nor is it an accusation that their symptoms are all psychological. it is out of compassion that medical practitioners want to have clear diagnoses from which to work. If NCGS is either an illusion, or is being highly overdiagnosed, then those people falsely diagnosed with it are being misdiagnosed. Their true diagnosis is therefore being missed, as is the opportunity to properly treat them.

Also – if we can confidently say that NCGS is a distinct syndrome, then proving it will help future research aimed at figuring out what is causing the disorder.

22 responses so far

22 thoughts on “Gluten Free Defined”

  1. locutusbrg says:

    my two cents.

    I find it implausible that a multi-century staple product, suddenly developed into a broad dietary issue across an evolutionary population that has survived for thousands of years using this food as a primary food source. Lactose digestion would be an example of an evolutionary opposite. if it was a disproportionately high finding of gluten sensitivity across let’s say the Asian population, I would find that be more compelling. Given the fact that that population has primarily used rice as their staple crop. Most of the data available shows us a disproportionate finding in the Western European populations.

    Also given the fact that the majority symptoms are gastrointestinal in nature, there is a high degree of confirmation bias associated with symptoms. There is a lack of distinct laboratory, physiologic test, or physical exam findings that could diverge from other more common GI issues. This includes stress-related factors. People often forget what role stress and anxiety place in gastrointestinal symptomatology. I remind people that if you get diarrhea from stage fright, you don’t get a colonoscopy to check it out. You understand that stress and anxiety can give you stomach upset, and G.I. symptomatology. I’m certain that there are group of people who worry so much about this issue that they in fact develop the symptoms due to the worry.
    that said, I am not advocating skipping the proper testing and physical exam, or jumping to a stress-related diagnoses primarily. It is common in medical diagnosis to remind people when you hear hoof beats you think horses, but that doesn’t mean it cannot be a zebra.

    I also find it telling That if you remove the title from the symptom list you will see a strong correlation between the symptomatology of this problem, and other disproven syndromes.

    In my opinion. It would have to be very strong evidence to convince me that this syndrome exists beyond a small percentage of people who have definitive celiac disease.

  2. Enzo says:

    As Steve mentions, we need more data on what the connection (if any) between gluten and more nebulous gastrointestinal problems is.

    But I think another issue that we are all aware of is the branding and marketing behind “Gluten free.” These companies are not creating their product to market exclusively to Celiac and potential NCGS patients — they are clearly after the health-conscious consumer. It’s another industry embracing pseudoscientific claims that exploit public ignorance.

    I would like to know the percentage of people buying gluten-free who have experienced NCGS-like symptoms prior to adopting this diet. Those that had problems and THEN asked “what if I switch to gluten free?” I’d also like to know what percentage of people buy gluten-free products alongside gluten-containing products.

  3. 2kids2dogs says:

    My adult daughter was diagnosed with gluten “sensitivity”. She had antibodies levels well outside the norm (the highest the Dr had ever seen), but her Dr said that she should just try avoiding gluten and skip the intestinal biopsy as she felt it was not necessary and my daughter could not easily afford the co-pay. Thus she cannot say she has Celiac disease, but has avoided gluten for nearly 3 years and has seen a pretty much total correction of the bloating and constipation that she had for years. For us the labeling is a boon. While you may scoff that some things without gluten are labeled gluten free, there are many things, like oats and corn, that are frequently processed in plants with wheat or other gluten containing grains and can be contaminated. She has had several severe reactions when eating things she thought were safe.
    However, the willy-nilly adoption of an aversion to gluten by people who hop on all the latest food trends (raw food or paleo diets anyone?) does make it harder to convince people that this is not a lifestyle choice…as she says, she would LOVE to eat good bread and pizza crust again…but alas the consequences are not worth it. As my vegan sister says, her diet is a choice, my daughter’s is not…

  4. ccbowers says:

    “Meat, dairy, water, fruits and vegetables do not contain any gluten. It’s interesting that the FDA will allow these foods to be labeled gluten-free also. This is a classic example of true but misleading.”

    Yeah, thats a tough one. Most foods that are to be labeled as gluten free are inherently gluten free (the only exceptions would be foods that were processed to remove gluten, which is likely a smaller percentage of total products), so if the FDA didn’t allow it for some, it would need to come up with reasonable criterion for disallowing it for those foods. I imagine that they realized that not allowing this label for certain foods would be problematic from many angles and there would be a large element of arbitrariness to creating the criteria. Many people have an attachment to the idea (an incorrect one) that more information is always better. Problems can occur when more information becomes noise and selective information becomes misleading

  5. ccbowers says:

    “I would like to know the percentage of people buying gluten-free who have experienced NCGS-like symptoms prior to adopting this diet.”

    This is also problematic, because it is very difficult for people to identify the causes of their symptoms given all of the confounding variables with nonspecific GI symptoms. Even worse is that most people do not realize how terrible they are at identifying the causes of their symptoms, because they lack a sufficient background in skepticism. If you ask a person how they arose at a given dietary restriction, be prepared for a struggle with logic. Often the explanation is a vague tenuous connection between erratic nospecific symptoms and erratic consumption of a particular ingredient. Even with a good background in skepticism, it is easy to be fooled by post hoc fallacies, because the timing of symptoms may not be what a person expects (e.g. assuming that the last meal cause symptoms as opposed to several meals or days ago).

  6. rezistnzisfutl says:

    Many people have an attachment to the idea (an incorrect one) that more information is always better.

    This is a phenomenon we often see when it comes to GMO labeling debates. It’s not longer information when what’s on the label actually obfuscates the intended result, which is to inform the consumer. Worse yet, often the mis/disinformation campaigns waged by the likes of such as anti-GMO, anti-vax, etc, would likely have their desired effect of warding off consumers with the misguided notion that something is harmful or unhealthy when labeled as such, or diverting them to products that have no additional health benefits. As with labeling foods GMO, labeling foods gluten-free that never contained gluten in the first place is, in my estimation, a borderline deceptive marketing campaign.

  7. ccbowers says:

    “As with labeling foods GMO, labeling foods gluten-free that never contained gluten in the first place is, in my estimation, a borderline deceptive marketing campaign.”

    I agree that there is a similarity with respect to the use of labeling by manufacturers (by appealing to ‘alternative health’ trends), but there is an important difference – gluten actually has health consequences for some people. Labeling something ‘GMO free’ has not been shown to add meaningful health information about that product.

    At the very least 3 million Americans need to know whether a product has gluten (and let’s leave open the possibility that there may be some others that may need to avoid gluten for less serious reasons, which could add to this number), and having meaningful labeling would at help those people. Even if all of those people know that water never has gluten, would they necessarily know that an obscure grain never has gluten?

    Instead of teasing out which foods a person should know never has gluten and which ones people don’t know, the FDA probably simplified that process to allow the labeling if it were true. Also most foods in a supermarket are processed with many ingredients so that allowing labeling avoids a person having to read through lists to see if Rice Krispies (for example) has added gluten ingredients despite the fact that rice does not have gluten.

    We already have this type of issue with labeling for cholesterol, fat, sodium, etc. For example labeling a product cholesterol free when it is a plant based product is redundant because cholesterol is only found in animal based products. That’s not to say that allowing this type of labeling is not problematic to some degree, but I’m not sure that there is a better approach.

  8. JustinWilson says:

    I’m looking forward to this. If my “gluten-free” friends really want to cut it out of their life they will at least know which products do not contain gluten. I wish them the best of luck, but I know for a fact 40% of what they eat has plenty of gluten to go around. It will be a new experience for them when they have to throw out so much of what is currently in their daily diet because of their new-found information.

  9. LittleBoyBrew says:

    As a home brewer and general beer geek, I have seen significant interest in home brewing gluten free beers and an uptick in commercial brewers offering gluten free products (which is not easy, buckwheat and millet are poor substitutes for barley). It strikes me that “gluten free” is being marketed well beyond those who simply have celiac disease. Sort of trendy like being vegan or eating a low carb diet.

  10. ccbowers says:

    “I have seen significant interest in home brewing gluten free beers and an uptick in commercial brewers offering gluten free products”

    This is a side benefit of the recent fad of gluten free products: For those who really need to avoid gluten, there are more options. Some of the gluten free beers available now are actually drinkable, although many of them do use barley as the carbohydrate source (and remove the gluten). I’m not a home brewer nor do I unnecessarily avoid gluten but many commercially available gluten free beers appear to use sorghum.

  11. rezistnzisfutl says:

    Just to be clear, I wasn’t criticizing the FDA for creating more precise definitions of “gluten free”, but rather the more specific point of the pseudoscience behind gluten-free fad diets and anti-GMO. It’s been my observation that people often associate organic, non-GMO, gluten-free, and all natural, with the erroneous assumption that those things are necessarily healthier and better all-around.

    I agree that it’s good to have gluten free labeling, where it is applicable. I don’t think, however, that it should be applied to just any product (eg, bottled water), as that is, in effect, deceptive marketing, IMO.

  12. eean says:

    I only eat gluten-free cholesterol-free apples. Can’t stand the other sort of apple.

  13. Bruce Woodward says:

    Next we will have peanuts labelled “may contain nuts”…

    Everyone knows peanuts are not nuts!

  14. Booker says:

    Your favorite website has an article on this today:

    It’s by an MD and it seems to make some exaggerated claims, starting with a small bit of evidence and taking it to pretty extreme conclusions.

    Many commenters refer to the bestseller, Wheat Belly, which has been ripped by reviewers, though that doesn’t seem to have hurt sales. This sure has the feel of the many many food fads of the past.

  15. mariner says:

    Steve, thanks for blogging on this topic. As a definitively-diagnosed celiac (rhymes with maniac), I’m grateful for the new definition, and to some extent, for the fad status that has resulted in many more GF products conveniently available on my local mainstream grocer’s shelves.

    A couple of observations:
    – The GF designation that I really trust is the one that is based on actual testing of product samples. My new favorite GF beer (the one that is brewed with barley but undergoes a proprietary process to remove gluten) cannot be labeled GF because it is actually brewed with barley. But they test every batch and give me a code that lets me look up the test results for the batch I am drinking.
    – “Gluten Free” is assumed to mean “much more expensive” due to extra measures to avoid cross-contamination, testing, etc. Could this also be a factor in the labeling of water, fruit, etc. as GF?

  16. Calli Arcale says:

    “Meat, dairy, water, fruits and vegetables do not contain any gluten. It’s interesting that the FDA will allow these foods to be labeled gluten-free also. This is a classic example of true but misleading.”

    I understand where you’re coming from, but I have to disagree for several reasons:

    1) How can a regulatory agency ban truthful statements? Carrots are generally gluten free; that’s self-evident. Eggs are gluten free. While you may feel the statement is too obvious to have any merit on a label, if the FDA were to start requiring all statements to be meaningful and relevant, I think you’d see how ludicriously impractical that would quickly become. Would celebrity endorsements have to also be banned, since of course it is not really relevant if Michael Jordan eats a particular brand of breakfast cereal? I think you’d have a serious First Amendment question in front of you at that point.

    2) In this case it actually is *not* irrelevant. Firstly, because it is not as obvious as one might think. While single egg clearly has no gluten added, processed products often do — and this can include even very minimally processed foods. Can you be sure those corn chips are gluten free? You’d hope so, but as I’ve learned from my cousin, who has very severe celiac sprue, you really can’t assume it to be true. Maltodextrin is an example of a very common ingredient in a lot of foods that you don’t at all associate with wheat, and one problem with it is that it can be made from wheat. Maltodextrin made from wheat should be presumed to be contaminated with gliadin. Most of it in the US is made from corn, but if you have severe celiac disease, you can’t take that for granted. And it is sometimes used on the surface of whole meats or vegetables. You’re not likely to encounter it at the produce stand or at the butcher, but I think the label could be helpful.

    Perspective: my cousin has severe celiac disease. She has to be careful about what brand of ice cream she uses. Seriously. She doesn’t just get a little malaise, either, like so many of the self-diagnosed gluten sensitive folks. She ends up in the hospital. She was diagnosed at age 6 months, when she was first introduced to solid foods, and her entire gut completely shut down. It was pretty dramatic.

  17. Calli Arcale says:


    Yes, many peanut packages are labeled “may contain nuts”. This is not because of confusion over what is a nut. It is because most factories that process peanuts also process tree nuts, and cross-contamination is likely unless they take special steps to control dust and sanitize all the equipment in between.

  18. steve12 says:

    “How can a regulatory agency ban truthful statements? ”

    This is a good point. While the manufacturers of many products clearly are intending to deceive consumers re: their competitors when it comes to this labeling, I can’t think of a way to actually enforce it.

    I feel bad for your cousin! I have to remind myself that there are people who really can’t tolerate gluten, because if one more person tells me that I’d be able to fly or shoot lasers out of my eyes if only I’d cut out the gluten I’m going to smack them (not really…).

  19. ccbowers says:

    Calli Arcale-

    I made those very same points above. Perhaps I was too wordy.

  20. Nitpicking says:

    I think that water bottle should also be labeled “Fat-free, sugar-free, no sodium, zero calories!”

  21. BillyJoe7 says:

    …well, to nitpick Nitpicking, the bottle is 100% plastic.
    As for water…get it from a tap. No plastic to pollute our rivers and oceans, and no advertising to argue over.

  22. Davdoodles says:

    # Dr Novella: “I also have to emphasize that doubting the NCGS diagnosis does not represent a lack of compassion for sufferers, nor is it an accusation that their symptoms are all psychological.”

    So you are saying they are liars?

    /typical faux-outraged supplement peddler.

    # BillyJoe7: “As for water…get it from a tap. No plastic to pollute our rivers and oceans, and no advertising to argue over.”

    Better still, buy some of that new-fangled dehydrated water.

    Much cheaper to transport, safe for infants. Just add water….:)

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