Gluten is the name given to a class of proteins found in wheat and several other grains. It’s got some bad press in recent years, and in recent years gluten-free diets have become something of a health fad. Some popular health movements have claimed that gluten is inherently bad for us and blamed it for everything from digestive problems and inflammation to neurological disorders, osteoporosis, cancer, and much more. Is there any truth in this? Should we be avoiding gluten, or is it just another health myth?

Celiac disease

Let’s start with one case where we know that gluten can be damaging to health. That’s in people who have celiac disease. This is an illness that’s been known about since at least the second century A.D., in which consumption of gluten triggers an immune response in the body causing damage to the lining of the small intestine, and a range of symptoms including nausea, diarrhea, gastrointestinal pain, bloating, and nutritional deficiencies due to the poor absorption of nutrients, as well as a range of other less obviously related symptoms including fatigue, depression, neurological problems, and joint pain.
Celiac disease is thought to affect about 1 percent of the population, although a high proportion of those haven’t been diagnosed and may be unaware of the condition. It can be picked up by a blood test, providing that the person’s diet at the time of the test contains gluten.

If you’re part of that one percent of the population that has celiac disease, then there’s no question—gluten is bad for your health. Not only can it give you unpleasant symptoms in the short term, but even small amounts of gluten can damage your gut and lead to longer term complications which are thought to include osteoporosis and even certain kinds of cancer. The only treatment for celiac disease is a lifelong gluten free diet.

Wheat allergy

There’s at least one other group of people whose symptoms tend to improve when they’re put on a gluten free diet, even though their condition may not relate directly to gluten. These are people who suffer from wheat allergies. These are different from celiac disease, in that although both are immune reactions, they involve different antibodies and immune cells. In addition, while celiac disease is specific to gluten, a wheat allergy can involve any of the proteins in wheat. Although gluten may not be a culprit, a gluten free diet is likely to also exclude the other wheat proteins, explaining the positive response to the change in diet.

What about the rest of us, though?

Non-celiac gluten sensitivity

It’s been hypothesized that there may be another, potentially much larger group of people who don’t have either celiac disease or wheat allergy, but still suffer from digestive problems (and perhaps other symptoms, too) when they eat food containing gluten. This has been given the name non-celiac gluten sensitivity. This is currently a controversial condition – some researchers question whether it exists at all, while other people claim that it affects a considerable proportion of the population.

The symptoms have some overlap with irritable bowel syndrome, including abdominal pain, bloating, and diarrhea, and it’s also been suggested that in some people it may be linked to extra-intestinal symptoms including things like headaches, fatigue, fibromyalgia and neurological disorders.
A google search for “gluten intolerance” brings up lots of articles claiming to debunk this fad, with headlines like “gluten intolerance is fake, study says.” The study that triggered much of this media skepticism was published in 2013, and while the popular press have (as usual) overplayed the implications (it doesn’t go as far as to prove that there is “no such thing” as non-celiac gluten sensitivity), it is certainly an interesting finding that deserves a closer look.

FODMAPs

There are a group of carbohydrates that have been implicated in some cases of irritable bowel syndrome. They’re referred to by scientists as FODMAPs (short for “Fermentable Oligo-, Di-, and Mono-saccharides And Polyols”, which is quite a mouthful). The carbohydrates found in wheat (fructans) fall into this group, although it also contains a number of other foods too. FODMAPs are poorly absorbed in the small intestine, often leading to the production of gas and in some people digestive discomfort, and a diet low in these substances has been shown to be helpful for many people with IBS. The 2013 study showed that a group of people with self-diagnosed gluten sensitivity who had already been placed on a low FODMAP diet (leading to an improvement in their symptoms) did not show a consistent worsening in symptoms when “challenged” by adding gluten back in to their diet. This raises the possibility that in many of these cases it may be the fructans that people are reacting to rather than the gluten. Does this difference matter? Well, a diet low in FODMAPs is not quite the same as a gluten free diet, and people may find it less restrictive as well as potentially more effective at controlling symptoms.

So is “non-celiac gluten sensitivity” really a sensitivity to FODMAPs instead? That may not be the whole story. It’s possible that there may still be a smaller number of people who are genuinely gluten sensitive. One possibility that has been raised is that gluten may have an effect on mental health and psychological wellbeing (perhaps somehow related to abnormalities in serotonin production). This could in turn affect the sensitivity of the digestive tract; irritable bowel syndrome is known to have a correlation with anxiety and depression.

This research is ongoing – the case is not closed yet. However, it seems fair to suggest that true gluten sensitivity is rarer than many people believe.

Finally, there are no doubt plenty of people with no food allergies or intolerances at all, whose health nonetheless improves when they eat a gluten free diet. Why? Because any sufficiently complicated set of dietary rules requires you to think more carefully about what you’re eating. It means you can’t reach for a handy chocolate bar from a vending machine if you’re a bit hungry – snacking now involves scrutinizing lists of ingredients carefully. Along with gluten, you’ll probably be eating far less processed food, which often comes with an extra load of calorie dense, cheap carbohydrates. In the short term, especially, this can lead to weight loss and an improved sense of wellbeing. (The corresponding downside, of course, is a much more limited diet that carries a possible risk of nutritional deficiencies.)

The verdict: True, for some people, but perhaps fewer than you might think

There are certainly some people who should avoid gluten, and that’s people with celiac disease. It’s possible that there are some non-celiacs who may be affected by gluten, but if you find that you feel better on a gluten free diet, bear in mind that this could well be for other reasons. You may either be sensitive to other components of wheat, or it might be that changing your diet has had beneficial effects that were nothing to do with wheat at all.