As I sift through the ruins of organized skepticism, I recall something that always bugged me.
Celiac disease is an autoimmune disorder that causes a bunch of chronic gastrointestinal problems. The treatment to celiac disease is to switch to a completely gluten-free diet. However, people with celiac are not by themselves the cause of the many gluten-free products sold in stores. Many people buy those because they believe they have a different condition, Non-Celiac Gluten Sensitivity (NCGS). They believe that when they go on a low-gluten or gluten-free diet, they have fewer gastrointestinal symptoms (e.g. they feel less bloated). I say “believe”, because there is no consensus that NCGS exists.
The standard skeptic’s line on NCGS is that there is no evidence that it exists, and there is no reason for people to go on gluten-free diets unless they think they have celiac disease. One study that has been used in support of this position, is a paper from 2013, which says in the title “No effects of gluten in patients with self-reported non-celiac gluten sensitivity“.
The interesting thing about this paper is that it says that people who report NCGS do experience a significant reduction in symptoms when they change their diet. However, the important change in their diet is not the elimination of gluten, but the elimination of another category of chemicals, known as FODMAPs. FODMAPs are generally present in the same grains that include gluten, so it’s easy to get them confused without having a study designed specifically to separate them. In other words, it is possible that people who believe they have NCGS are correct about having symptoms that improve with a change in diet, but incorrect about the source of those symptoms.
I recall that back in 2013, skeptics were saying, “This is another confirmation of what we’ve been saying all along: NCGS doesn’t exist.” And I recall reading the news reports and thinking, wait. This means we were wrong. People who thought they had NCGS were correct to change their diets. We were wrong. Why weren’t skeptics acknowledging that they had been wrong?