You’ve probably seen the recent glut of sensational headlines in the media proclaiming that non-celiac gluten sensitivity is some kind of widespread collective delusion—simply a figment of the imagination of anyone who claims to experience it.
These stories point to a new study which found that a group of patients with irritable bowel syndrome (IBS) were not sensitive to gluten. (1) The researchers who performed this study had previously published a paper showing that IBS patients were sensitive to wheat, and that removing wheat from their diet led to an improvement of symptoms.
However, in this new study, the authors specifically isolated gluten and found that there was no difference in symptoms between the patients eating high-gluten diets and those eating low-gluten diets.
This is a significant finding, but to claim that it proves that non-celiac gluten sensitivity doesn’t exist is both inaccurate and irresponsible. It’s a great way to get clicks and generate attention, but it’s an extreme distortion of what the study actually found.
Why this study doesn’t disprove gluten sensitivity
First, this study examined the effects of gluten in a specific population: people with irritable bowel syndrome. Even if it is true that gluten sensitivity is no more common in people with IBS than in people without IBS (which is premature to conclude on the basis of a single study), it does not overturn the large body of evidence that links non-celiac gluten sensitivity to a variety of health problems ranging from allergies to schizophrenia to autism spectrum disorders. (2, 3, 4, 5)
Second, this study does not suggest that people with IBS—or anyone else with gluten sensitivity—should feel free to start chowing down on wheat. In fact, it suggests the opposite. For the first week of the trial, all patients were put on a gluten-free diet that was also low in FODMAPs (a class of carbohydrates present in wheat, as well as other foods).
After this lead-in period, the participants were assigned to one of three groups: a high-gluten diet, a low-gluten diet, and a placebo. Those on the high gluten diet were given 16 grams per day of purified wheat gluten; those on the low gluten diet were given 2 grams per day of purified wheat gluten plus 14 grams per day of whey protein isolate; and those on the placebo diet were given 16 grams per day of whey protein isolate.
The majority of participants experienced a significant improvement of symptoms during the 7-day gluten-free, low FODMAP lead-in period. But there was no difference in symptoms between the high gluten, low gluten, or placebo groups during the subsequent treatment period. In other words, patients did react adversely to wheat, but they did not react to isolated gluten.
This of course suggests that something other than gluten in the wheat was causing the problems patients experienced. We now know that there are several compounds in wheat other than gluten that could be to blame. These include not only FODMAPs, but also agglutinins (proteins that bind to sugar), prodynorphins (proteins involved with cellular communication), and additional proteins that are formed during the process of wheat digestion, such as deamidated gliadin and gliadorphins (aka gluteomorphins). (6)
Another possibility is that both the placebo and low-gluten groups were reacting to the whey protein. Whey is >99% casein- and lactose-free, which is what most people who are sensitive to dairy react to. However, it is certainly possible for people to react adversely to whey, and in my experience this is more common with patients with digestive problems. If some of the “placebo” and low-gluten patients were, in fact, sensitive to whey, then that would invalidate the results of the study.
How to find out if you’re sensitive to wheat, gluten, or both
This study showed that for people with IBS on a low FODMAP diet, eating isolated gluten does not cause symptoms. But one might ask: who cares? Do you eat isolated, purified gluten? Do you know anyone who does? I doubt it. People eat wheat—not gluten. And as both this study and numerous other studies have demonstrated, there are several components of wheat other than gluten that cause problems.
In practical terms, this study still supports the idea that patients with IBS should avoid wheat, because it contains FODMAPs and possibly other compounds that make them feel worse. What this study does tell us is that it’s possible that IBS patients may be able to tolerate other non-wheat products that contain gluten, presuming they are low in FODMAPs and other compounds that they may react to.
Here’s the best way to determine if this is true for you:
- Remove all gluten-containing foods and products from your diet for 60 days.
- At the end of the 60 day period, cook up a bowl of barley, eat it, and see what happens.
- A few days later, eat a piece of wheat bread.
Barley is a gluten-containing grain that is low in FODMAPs. If you react to it, that suggests you’re intolerant of gluten or other gluten-like compounds. If you don’t react to barley, but you do react to the wheat bread, that suggests you are intolerant to something in wheat specifically.
You may be able to safely consume gluten-containing products other than wheat—though it’s worth pointing out that many of these products (primarily grains and processed foods) would not be foods you should be consuming regularly anyways.
Is “non-celiac wheat sensitivity” a better label?
If there’s an important takeaway from this study, it’s this: non-celiac wheat sensitivity may be a different clinical entity than non-celiac gluten sensitivity. The former would be used to describe patients that are intolerant of wheat, but are able to eat other gluten-containing foods without symptoms. The latter would apply to patients who are sensitive to any food or product that contains gluten, including wheat. In fact, this distinction was originally proposed by researchers in response to another study which found no effects of gluten in patients on a low FODMAP diet. (7)
Now I’d like to hear from you. Are you ready to give up on the idea that you’re gluten sensitive after reading this study? Why or why not? Have any of you already done the experiment that I suggested above? What did you discover?
沒有留言:
張貼留言