Does non-celiac gluten sensitivity exist?
Gluten free diets have become widespread over the past few years, from people with celiac disease, who have a true medical reason for avoiding gluten, to people who mistakenly believe it will help them stay healthy or lose weight. There is also a group of people in the middle of the spectrum: those who haven't been formally diagnosed with celiac disease, but suffer from similar symptoms and believe their bodies are sensitive to gluten nonetheless.
The existence of non-celiac gluten sensitivity, as it's called, has been under debate recently in the medical community. In December, researchers from Australia published a study in which people who didn't have celiac disease but self-reported sensitivity to gluten were placed on diets containing low or high amounts of gluten, or a placebo. Those on the placebo diet — meaning no gluten at all — still reported a worsening of their symptoms. The culprit, researchers believe, may not be gluten at all, but instead a combination of carbohydrates and sugars known as FODMAPs, which are often found in gluten-containing foods.
Does this new research mean there's no such thing as non-celiac gluten sensitivity?
Stefano Guandalini: Not necessarily. It does mean, however, that what we now call non-celiac gluten sensitivity is likely to be a mixed bag of issues. Interestingly (and I was able to convince a panel of experts in Italy of this during a round table last week) there is to date not one scientific proof that gluten as such is involved in any of the patients reporting gluten sensitivity.
We also spoke to Guandalini about this research earlier this year, after preliminary data was presented at the 15th International Celiac Disease Symposium. He explained the difference between sensitivity to the protein gluten and the sugars and carbohydrates known as FODMAPs:
Guandalini: To make a long story short, FODMAPs are a bunch of sugars and carbohydrates that are very poorly digested and absorbed. If you eat a lot of it, especially if you have a sensitive gastrointestinal tract like patients who have irritable bowel syndrome, for instance, ingesting these products might end up causing discomfort, abdominal pain and flatulence, similar to most of the complaints by people who call themselves gluten sensitive. So the investigators took these patients who were already on a gluten free diet and further eliminated all these FODMAP ingredients. After a week of this, they put them on a diet containing either gluten or placebo.
What they saw, to their surprise, was that at the end of the time during which they were eliminating all sorts of FODMAPs in addition to gluten, most of the symptoms were completely gone. The subjects felt much better. So then they introduced, in a double-blind, placebo controlled fashion, two diets that contained different amounts of gluten: low gluten and high gluten, or a placebo diet, meaning still gluten free and remaining low on FODMAP. What they saw was that their symptoms recurred a little bit, but it was no difference. People on the high gluten diet were ingesting 16 grams of gluten, which is a lot, the equivalent of 100 grams of bread or pasta. These werepatients who were in the study because they said they were gluten sensitive, but they had less symptoms than the patients who were on a placebo diet and remained gluten free. So gluten caused no recurrence of symptoms.
Although this is a moving target and this research — which is outstanding, in my view — has some critiques, it tells you a fact: That we need to be extremely cautious in calling somebody gluten sensitive. It may be sensitivity to FODMAPs instead. It could have nothing to do with gluten at all.
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Stefano Guandalini, MD
Stefano Guandalini, MD, is the founder and medical director of the University of Chicago Celiac Disease Center, and Section Chief of Pediatric Gastroenterology, Hepatology, and Nutrition at the University of Chicago Medicine.See Dr. Guandalini's bio