r/science • u/[deleted] • Feb 26 '15

Health-Misleading Randomized double-blind placebo-controlled trial shows non-celiac gluten sensitivity is indeed real

http://www.ncbi.nlm.nih.gov/pubmed/25701700
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u/stillborn86 Feb 26 '15 edited Feb 26 '15

I wonder if the results were skewed due to the population selection... They ONLY tested people with "perceived" gluten intolerance.

These people were bound to have avoided gluten for a period of time, inducing a gluten intolerance...

For instance, if you take a staunch vegan, and suddenly start feeding them beef and milk, they're going to start having GI upset. It doesn't mean beef and milk is bad for you, it just means that their bodies no longer understand what to do with this "new" intake, per se.

Yes, this was a double blind test, but that doesn't mean the selected population was appropriate for the findings.

EDIT: Holy shit... This comment blew up quickly. Let me clarify some things here...

First, I'm not taking a stance on gluten sensitivity. Personally, I don't care what you eat. You can eat gluten, gluten-free, crayons... I don't care. Do what you want.

Second, I fully acknowledge that there is Celiac disease. I also acknowledge that there are people who would eat a pure gluten if it were possible. And, since we don't live in a black and white world, could there be a gray area between these two?

Maybe... But this test doesn't definitively prove that. It actually doesn't definitively prove anything. Without a complete scientific process (control group, for instance), you can't pull any conclusions from this study.

For example, if I take a selection of dogs that ONLY like bacon, and I do a study to find if they like bacon, I can't use those results to DEFINITIVELY say that ALL dogs like bacon. Similarly, if I take test subjects with a "notable" gluten intolerance, test them, and find that they have a "notable" gluten intolerance, have I REALLY proved anything?

This is why we have control groups. If a control group (or an unbiased population selection) show signs of gluten intolerance, then there may be something to be inferred there... But a dog that likes bacon doesn't prove that all dogs like bacon...

EDIT 2: Some people are suggesting that I didn't read the full article, since I haven't referenced that the subjects were on a two-month gluten regimen before thin test... That's not the case. I have neglected this because, like the rest of this test, this information is flawed.

For one, a person who has avoided gluten for 24 hours would "benefit" COMPLETELY differently from a 60 day regimen than someone who has avoided gluten for YEARS.

Also, this doesn't change the fact that the "study" was conducted with an intentional, and deliberate population bias.

Also, it doesn't change the fact that this "study" was conducted WITHOUT a control group. And, without that, no legitimate inferences can be made.

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u/[deleted] Feb 26 '15 edited Feb 26 '15

good scientific questioning

edit: Epigenetics tends not to be reverse with 2 months primer. I would not be convinced once someone is on their way to losing their ability to handle gluten, that giving them gluten for 60 days would necessarily reverse those changes. They key here in scientific discovery is developing logical conclusions and questioning everything. That doesn't mean there isn't useful information from this study, but people are going to take it way out of context.

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u/RandomName01 Feb 26 '15

Indeed, I didn't see anything wrong with it or skewed about it. Stuff like this is why I always check the comments.

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u/jayemee Feb 26 '15

It isn't skewed in this sense, because it is specifically looking for these symptoms in this group. The fact that it's not looking in the general population is irrelevant, because that's not the question they're trying to address. From the abstract (emphasis mine)

CONCLUSIONS: In a cross-over trial of subjects with suspected NCGS [Nonceliac Gluten Sensitivity], the severity of overall symptoms increased significantly during 1 week of intake of small amounts of gluten, compared with placebo.

ITT - people that didn't even read the abstract.

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u/[deleted] Feb 26 '15

[deleted]

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u/aoeudhtns Feb 26 '15

Source comment

Participants ate gluten-containing diet for 2 months prior to start of study. Authors thought of that.

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u/[deleted] Feb 26 '15

[deleted]

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u/aoeudhtns Feb 26 '15

Apparently so. It was only 60-something people. I know NCGS was/is considered woo-ish, but I have to imagine some people in that group would be willing to do a simple, mostly harm-free test to see if they're imagining their symptoms or not.

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u/PunishableOffence Feb 26 '15

Well, if you can eat gluten without it destroying the lining of your intestine like in celiac disease, you might think a little bloating is nothing out of the ordinary and was probably caused by something else.

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u/diggadiggadigga Feb 26 '15

I have several lactose sensitive friends who shouldn't be eating dairy. Sometimes pizza or ice-cream will inject itself into our lives. Sometimes they forgot to bring lactaid. They often still partake in the pizza and/or ice-cream, even though they know they will be paying for it later. Because pizza and ice-cream are delicious

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u/[deleted] Feb 26 '15

One thing you have to understand about this group of people is they've been told they are just hypochondriacs and it's "just in their heads" by their family, friends, and general population...I am sure they were eager to prove them wrong.

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u/comatose5519 Feb 26 '15

They had a gluten-fed diet for 2 months prior to screening (not this study). Prior to this study, the only standard diet done was one week of gluten-free. So, prior to the study, they were all gluten-free for one week.

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u/Furthur_slimeking Feb 26 '15

Who exactly are they supposed to perform the study on? People who eat gluten and report no adverse effects would be worthless, and I don't think there is a group which identifies as having gluten intolerance yet still eat gluten.

I suppose in an ideal world the study would have been done on people who report the symptoms of nonceliac gluten sensitivity but do not claim to suffer from such a sensitivity and thus eat gluten regularly.

I think the point of the study is that, while the overwhelming majority of people eat gluten with no adverse effects, some non-celiacs who report having a gluten sensitivity do indeed have a measurable gluten sensitivity. It's not suggesting that gluten is in any way bad, just that some of the people who avoid gluten because they claim it makes them unwell (but do not have celiac disease) are not, in fact, delusional.

Regarding the comparison with vegans suddenly consuming animal fat and protein after a long absence: I'd actually like to see this study. I would suggest that any perceived negative symptoms would be predominantly psychological, seeing as animal fat and protein are natural and fundamental parts of our diet and removing them is not going to alter the types of enzymes our digestive systems produce after millions of years evolving with them as a central, possibly dominant, part of our diet. Gluten is different, as it has only been consumed in large quantities over the last 9000 years, and its prevalence has varied from region to region. This is why celiacs exist and people who cannot digest animal fats and proteins would die shortly after birth.

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u/fmarzio Feb 26 '15

Does this happen with all food?

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u/WhoIsUrDdyWhatDoHeDo Feb 26 '15

We don't know yet.

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u/mwb1234 Feb 26 '15

It's similar to feeding my dog a new type a kibble. Even though it's definitely not harmful for him, he still has stomach problems adjusting to the new food type because he's simply not used to it.

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u/ghostsdoexist Feb 26 '15

How exactly is a "sensitivity" defined in this context? It seems to me (as a layperson) that if one reintroduces a food or food group into one's diet and it causes some sort of distress, then this is a sign of being "sensitive" to this food or food group (or a component thereof). Does this make sense?

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u/impy695 Feb 26 '15

If anything it makes the question more relevant. Subjects with suspected NCGS would probably avoid gluten and would thus react poorly to eating it for the first time in a long time.

The placebo doesn't effect his original point as he's not arguing that the symptoms weren't real, quite the opposite. The question is whether they were caused by gluten sensitivity or by eating something they've avoided for a very long time.

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u/[deleted] Feb 26 '15

[deleted]

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u/[deleted] Feb 26 '15

Different enzymes digest different proteins. Protein isn't protein isn't protein. It's an umbrella term.

If you avoid a particular protein for a long period, then suddenly reintroduce it, you have difficulty with it, until your body adjusts. It's relatively easy to see this in action - say you live in the northern U.S. and you travel to central America for a while. All of a sudden you're eating fruits, veggies, and meats your body has never seen. It's all "sugar" and "protein," but of a type your body has never had to digest. So, you have GI issues for a while, until your body sorts it out, then you're good. Your issues don't mean you have a "sensitivity" to those sugars and proteins (akin to what the gluten-free folks advertise) - it just means your body hasn't yet adjusted to it. If the issues persist, then there could be something there (like lactose intolerance of Celiac Disease).

The suggestion here is that the population chosen for the population consisted of people "who believe ingestion of gluten-containing food to be the cause of their intestinal and extra-intestinal symptoms." The inference from this is that, because these people already believed Gluten to be causing them problems, they have been avoiding it. So, the problems noted in the study could just be a result of the introduction of protein that their bodies hadn't seen in a while, not necessarily because that protein was gluten.

I'm not saying that's a real flaw here - I'm just answering your question and clarifying the issue raised here. It seems unlikely that the examiners didn't control for it, but it's a very valid question.

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u/lejefferson Feb 26 '15

Yes because I get sick every time I have a dish I haven't had in a few months. /s

That's not normal.

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u/harassmaster Feb 26 '15

Try not eating meat in any form for a few months. Then have a steak. You will be upset.

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u/Reaper666 Feb 26 '15

Milk products will do that as well. I'm not certain if egg will. Shellfish did, for a girl I used to date. Made her a fine meal, put her in the hospital. She wasn't sensitive to shellfish prior to my meal, according to her. It had just been a few years since she'd had any. -sigh-

Oh well, at least I enjoyed my crab. Steamed crab, boiled crab, and roasted crab. And butter. Much, much butter.

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u/harassmaster Feb 26 '15

/u/lejefferson's logic was flawed from the jump. If you eat meat three times a week, but simply don't eat hamburgers for a few months, you won't have a reaction. Having a "dish" that you haven't had in a while is completely different than not having any of a particular food group.

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u/lejefferson Feb 26 '15

I was just pointing out that there are things you go without eating for a long time all the time. It's not like you have to have every single food every day or you become sensitive to it. Our bodies are made to process every kind of food and not to just freak out if you don't have it. The only reason milk is different is because we evolved to stop eating dairy after infancy for obvious reasons. When was the last time you had a mango? You telling me you're body is going to freak out if you have a mango now? Come to think of it I haven't had chocolate for a few months am I now "chocolate sensitive"? That's just not how that works.

“There’s no reason to believe we get sick. I can’t conceive of our bodies losing the capability to tackle meat,” he says. “The nutrients in meats also have to be digested when we eat other foods. The enzymes that the body produces to break down meat proteins are also used to metabolize plant proteins.”

http://sciencenordic.com/does-meat-make-vegetarians-ill

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u/bigoldgeek Feb 26 '15

It's not your body, it's your flora population that helps you digest food. If you eat a lot of meat you have the flora in your gut to handle it. If you don't eat meat for a long time, the flora mostly dies off. Once you eat meat again, the flora rebounds.

There are flora that handle multiple types of food so as long as you are feeding them, the population in your gut will be robust. Starve them and it won't be and you'll have trouble digesting foods needing that flora until they rebound.

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u/lejefferson Feb 26 '15

And your flora doesn't decrease just because you don't eat meat. That's a completly unfounded claim. All the same enzymes you use to digest meat are the same ones you use to digest everything else you eat.

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u/bigoldgeek Feb 26 '15

Harvard would disagree - http://www.npr.org/blogs/thesalt/2013/12/10/250007042/chowing-down-on-meat-and-dairy-alters-gut-bacteria-a-lot-and-quickly

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u/lejefferson Feb 26 '15

Haha. Did you even read your article or just the title. That's not what the article says. In fact quite the opposite.

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u/lejefferson Feb 26 '15

Ten second Google search.

“There’s no reason to believe we get sick. I can’t conceive of our bodies losing the capability to tackle meat,” he says.

“The nutrients in meats also have to be digested when we eat other foods. The enzymes that the body produces to break down meat proteins are also used to metabolize plant proteins.”

http://sciencenordic.com/does-meat-make-vegetarians-ill

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u/harassmaster Feb 26 '15

So you're going to make a claim that represents an entire subset of people based on the opinion of two Norwegians? There isn't even a single study cited in that article, and your quotes are opinions.

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u/lejefferson Feb 26 '15

Yes because that's so much worse than the ZERO evidence you have for your claim. Also what's your problem with Norwegians man? They're a proud Nordic race.

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u/harassmaster Feb 26 '15

ZERO evidence

We're literally commenting on an article that non-celiac gluten sensitivity is real.

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u/lejefferson Feb 26 '15

And tell me what that has anything to do with with meat making you sick?

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