Non-Coeliac Gluten Sensitivity Probably Doesn't Exist

Debunking the popular health fad of going gluten free.

Pictured: Delicious gluten. Photo by Mae Mu on Unsplash

As the husband of someone with coeliac disease, I’m very familiar with being gluten free. Sometimes it’s easy, like when you’re travelling in Vietnam and all you have to do is avoid the bread. Sometimes it’s less easy like when you want to make mapo tofu and even after YEARS of looking you still can’t find Chinese fermented soybeans that are made without wheat. Seriously, if anyone knows a brand please leave a comment, I’ve left them unlocked. Same with gochujang.

Aside from the odd Asian product, however, it is true that being gluten free has never been easier. I remember when we first started dating, 13 years ago, there was only one commercially available brand of gluten free bread. They had 2-3 loaves, which were all some variation on baked rice and corn flour with some thickeners and raising agents to make a loaf. Now, there is an entire section of the supermarket with dozens of loaves marked GF, and our local bakery even has a beautiful - and expensive - freshly-baked coeliac friendly sourdough.

The remarkable turnaround is partly because coeliac disease has become more widely understood. The rate of coeliacs in the population varies widely, likely due to genetics, from around 1 in 500 in some Asian countries like Japan to roughly 1 in 50 in places like Italy and Finland.

But it’s also largely because gluten has become something of a health fad. Influencers the world over are convinced that even non-coeliacs can improve their gut health by eliminating gluten from their diet. For the last decade, one of the main pieces of health advice that many in the wellness space will give you is to try avoiding gluten to help with any gut issues.

Except, there’s no evidence that this works. In fact, the data strongly suggests that non-coeliac gluten sensitivity simply doesn’t exist.

NCGS

Non-coeliac gluten sensitivity - NCGS - is the technical term for people who believe they are sensitive to gluten but have had negative tests for coeliac disease. Coeliac is usually tested for initially with antibody tests, but is confirmed with a biopsy of the gut. According to numerous websites online, this is a common affliction, purportedly related to things like inflammation in the gut.

There’s no strong reason why gluten should cause issues in people without coeliac disease. Gluten is, after all, a protein - or specifically, one of a group of near-identical proteins - that is broken down in your gut just like any other protein. For those of us who don’t have an autoimmune response where our immune system destroys the lining of our intestines after eating gluten, there’s no good physiological explanation as to why it should be harmful.

Pictured: Bread. Yes, I know, usually captions are more pithy, but this time it’s really just bread. Photo by James Harris on Unsplash

Nevertheless, NCGS has become a hugely popular fad in society. If you ask the general population how many of them believe that they have symptoms after eating gluten, the proportion who say that they do ranges from about 1 in 20 up to 1 in 7. That’s dozens of times higher than the rate of people who have either a positive antibody test or a positive biopsy for coeliac disease.

So NCGS is popular. But the problem is that the data we’ve got kind of shows that it doesn’t exist.

The first pool of data that we’ve got are what I would call treatment studies. These take a large group of people who say that they are sensitive to gluten and ask them to cut gluten out of their diet entirely, then slowly phase it back in. For coeliacs, this almost always results in slowly feeling better, then immediately feeling extremely unwell when they have gluten again after a long abstinence.

For people who believe they are sensitive to gluten, the evidence is mixed about whether there’s any benefit for these diets. One study from Italy in 2015 found that of 392 people who believed that they were sensitive to gluten - who said that they experienced symptoms after eating gluten-containing foods - 26 turned out to have coeliac disease, and 2 had a wheat allergy. Of the remainder, 27 reported improvements after cutting gluten from their diet AND said that reintroduction of gluten made them worse again. The other 337 people - 86% of the entire study - did not see any benefits from eliminating gluten from their diets.

This implies that of those Italian patients, 86% were wrong when they said that gluten was causing them issues. There was a small pool of people who believed that they had a reaction to gluten and may have been right, but even this was not confirmed in the paper.

Which brings us to the second type of study that looks at the idea of NCGS - challenge studies. I’ve discussed these before in the context of MSG, but basically challenge studies are where you give someone who believes that they have an issue with a substance either that substance or a matched placebo and see if they can tell the difference. When you do challenge studies on coeliacs, they always respond - it’s part of the diagnostic criteria.

But when you do properly blinded challenge studies on people with NCGS, they cannot tell the difference between gluten and a placebo substance. For example, this study from Australia in 2013 used a crossover design, where each person gets all of the treatments in a random order, to test people with NCGS. The patients were fed a carefully designed diet for a week that was low in FODMAPs, which are a group of carbohydrates that some people find hard to digest, and all artificial additives, then given the same diet plus either gluten, whey protein, or no additional protein for 7 days. People were blinded to which diet they were getting on any specific week.

Pictured: Lots of FODMAPs. Photo by Randy Fath on Unsplash

During the periods where they were getting either gluten or a control, people rated their symptoms and had a range of biological tests. The main finding of the study was that there was no difference between a gluten-containing diet and one that had no gluten in it for people with NCGS. Specifically, of the 37 participants, 6 reported some increase in abdominal symptoms when eating gluten and not one of the control diets. However, when the authors ran the challenge again for 3 days, these 6 people did not react to gluten. There were no people in the study who could reliably tell when the diet they were eating contained gluten vs a placebo control. If anything, the average symptom scores decreased slightly when people ate the gluten-containing diet.

In other words, the people in this study were not sensitive to gluten by either subjective or objective markers. Interestingly, all of the participants reported improving somewhat during the study, which implies that NCGS could possibly be due to FODMAP foods rather than gluten, but the study wasn’t designed to test this question.

It’s also interesting that these findings are not universal. The same authors as that study published a paper in 2011 showing that there were some (very minor) improvements in people who thought they had NCGS and were given a gluten-free diet. The difference between the papers? In the 2011 experiment, they didn’t really blind the diets - people got two pieces of bread and a muffin each day and could obviously guess when they were getting gluten free (trust me on this as someone who has been doing it for 13 years: you can ALMOST ALWAYS tell). In the 2013 experiment, however, they carefully blinded the diets by using small amounts of concentrated gluten or whey powders hidden in other foods.

To sum up: people with NCGS believe that they have a sensitivity to gluten. However, most of them don’t improve in terms of gut health when they eliminate gluten from their diet. Most do improve when they eliminate FODMAPs, which are a group of sometimes hard to digest carbohydrates present in many fruits and vegetables, but this isn’t proven to be a cause of NCGS. Also, when people with NCGS don’t know what they are getting, they report the same symptoms when eating whey protein or no protein as they do when getting concentrated gluten.

Bottom Line

The bottom line here is that you probably don’t have a sensitivity to gluten. If you think you are reacting to high-gluten foods, it’s worth talking to a doctor - you might have coeliac disease - but the evidence strongly suggests that people who are not coeliacs do not react to gluten in a negative way.

Rather, you may have issues with some foods that often are served with gluten. Or perhaps it’s not about the foods you are eating at all. Gut health can be complex, and we still don’t fully understand what drives things like IBS.

Regardless, the evidence shows that people who think that they are sensitive to gluten but are not coeliacs are usually wrong. You probably don’t need to avoid gluten to improve your gut health - perhaps try looking elsewhere.