Is "Gluten sensitivity" really a type of carbohydrate intolerance?

What’s the deal with gluten sensitivity? Gluten sensitivity as a proposed disease showed up in the scientific literature in the past few years. The key here is proposed, because there was evidence it might exist, but it remained in a scientific grey area because there was not a known mechanism behind it.

But enough people had already decided or wanted to decide gluten was bad that they took the proposed disease and ran with it, producing and selling a large volume of scientifically dubious diet books featuring “gluten sensitivity”.

A profitable food scare

One of the most popular studies was Gluten causes gastrointestinal symptoms in subjects without celiac disease: a double-blind randomized placebo-controlled trial. Whole Health Source’s Stephan Guyenet covered in in a popular post. It has been cited over a hundred times in the scientific literature and cited as evidence that gluten is bad in many popular diet books.

But the authors knew it had flaws (listen to an excellent podcast with one of them, Dr. Peter Gibson, here). And so they did another study to make sure it was gluten, a protein, that was the problem, and not carbohydrate intolerance.

Their new study, No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates, was published recently and is available for free online.

They found a source of gluten that was carbohydrate depleted. As Dr. Gibson says in the podcast “We wanted to do a more detailed and intense study to control for other things in the diet to ensure it was only the gluten we were looking at.” It was also cross-over and examined inflammatory markers in detail. Celiac disease, a gluten-related disease with a well-developed mechanism behind it, was ruled out in the subjects. The subjects were people with “IBS” who reported they felt better on a gluten free diet.

The diet they used for carbohydrate intolerance was FODMAPs (Fermentable, Poorly Absorbed, Short-Chain Carbohydrates), a diet developed in Australia for gastroenterological symptoms. They used it as their background diet and supplied all the food for the participants. The re-challenge trial diet was even more strict, eliminating FODMAPs, dairy, and low in naturally occurring and artificially added food chemicals “salicylates, amines, monosodium glutamate, as well as preservatives benzoates, propionate, sulfites, nitrites, sorbic acid, plus added antioxidants and colors”

Of course these diet books say “just try eliminating gluten and see how you feel.” But their eliminations usually violate basic scientific experimental principles. Most of these diet books have their adherents completely overhauling their diets. For example, Wheat Belly and a new book called Gut Bliss both tell dieters to not only eliminate all gluten from their diet, but to avoid gluten-free grain products. That is not testing the elimination of gluten, but the elimination of gluten AND foods with added sugar, starchy grain-based foods, etc. That’s testing a lot more than gluten intolerance. In the end I meet a lot of people who end up living a grey area, people who believe gluten is bad, but sometimes will eat it as part of their 20%. If they really have celiac this is devastating. If they don’t, they are living in fear for no reason.

Interestingly many of the subjects in the study got better on the diet they used than they had been on their previous gluten-free diets. This was my own experience as well, that I felt better on a FODMAPs diet, even though it contained some foods I once thought were kind of questionable, but in small amounts, than I did on a “paleo” diet. In fact I’d almost dread going to a “paleo” potluck these days, when so many paleo recipes seem along the lines of “let’s turn cauliflower (which is high in certain FODMAPs) into everything from faux rice to faux pizza crust.”

Of course this doesn’t tell us much about whether or not gluten plays a role in other diseases besides celiac, such as skin conditions. There are some hypotheses about that out there. Unfortunately, as “Stabby the Raccoon” said, paleo has become about “about scaring people over hypotheses.” Why? Simply because it’s profitable. Witness the rise of content farms that publish low-quality articles in this genre and manage to get massive amounts of hits and social media shares that can be reaped for ad dollars.

If you believe you might be affected by gluten, I’d recommend you get screened for celiac. If you don’t have celiac, I wouldn’t jump to the conclusion you have gluten “sensitivity” especially given how poorly defined this potential condition is. It seems wise to consider that FODMAPs might be an issue for you, which turned out to be the case for me.

Luckily, FODMAPs intolerance doesn’t have very much in common with celiac disease. Eating a little wheat is not going to cause a cascade of inflammatory reactions in your body. People who have issues with FODMAPs can typically tolerate some of the offending foodstuffs depending on individual differences and the preparation of that food. The re-challenge diet in the study also seems to point to dietary context as being an oft-overlooked consideration. Some people might be sensitive to one food only if another food is causing the initial irritation.

For example, I do not possess lactase persistence genetically, so technically I am lactose (a FODMAP) intolerant. In the real world, that means it might get uncomfortable if I guzzled a lot of fresh milk, but I can tolerate plenty of low-lactose dairy products and small amounts of fresh dairy. I also seem to be intolerant of the fructans in wheat. When I thought it was gluten, I ate a gluten-free diet that contained a lot of FODMAPs and often my symptoms were much worse than before. When I realized it wasn’t the gluten, I am now able to enjoy small amounts of wheat-containing foodstuffs. Same of fructan-containing alliums such as onions. I can’t enjoy them fresh, but when they are cooked down they do not seem to bother me. That means a lot for me since I love to travel and try a lot of foods. It might not be a biological “need,” but it is meaningful to me.