Gluten Sensitivity Has Not Just Been Proven
The authors of the study disagree.
"It does not represent crucial evidence in favor of the existence of this new syndrome," they write.
In the social media-driven era of "share first, ask questions later," it's easy to see why this mix up occurred. The study, "Small Amounts of Gluten in Subjects with Suspected Nonceliac Gluten Sensitivity: a Randomized, Double-Blind, Placebo-Controlled, Cross-Over Trial," sounds extremely rigorous. It's even published in a respectable journal, Clinical Gastroenterology and Hepatology, which is run by the American Gastroenterological Association. Moreover, the research team is based out of the University of Pavia, a top-notch university in Italy established over 600 years ago. So, when you read the study's abstract and learn that subjects given a gluten pill experienced higher levels of abdominal pain, bloating, and even depression compared to those given a placebo, you might think that non-celiac gluten sensitivity (NCGS) is indeed what's causing their uncomfortable symptoms and that, despite what RCS reported last May, the condition -- which supposedly affects more than 18 million Americans -- does in fact exist.
NCGS may very well be real, but science has yet to conclusively show it. And the current study doesn't alter the situation one bit.
The researchers recruited a total of 61 individuals suspected of having NCGS -- which means they reported experiencing deleterious symptoms like headaches, abdominal pain, and bloating after eating gluten but were confirmed to not have celiac disease or wheat allergy. The subjects were then put on a gluten-free diet for one week. Afterwards, they were split into two groups. In one group, subjects received 10 pills containing either 4.75 grams of gluten to ingest over one week (no more than two per day) and in the other, subjects received 10 pills containing 4.75 grams of rice starch. Each group then returned to a gluten-free diet for a week, after which they switched positions and spent another week taking either the placebo or gluten pills. Throughout the process, subjects recorded the severity of 28 different symptoms -- 15 gastrointestinal and 13 extraintestinal (i.e. anxiety, headache, rash, etc.) -- on a scale of 0 (absent) to 3 (severe). Both the subjects and the researchers giving them the pills we're blinded to the identity of the pills.
When the researchers tallied the data, they found that subjects reported a higher overall symptom score when taking the gluten pill.
"The median overall score after 1-week of gluten consumption was 48 (range 1-156), while after 1-week of placebo it was 34 (range 0-178)," they detailed.
Individually, only six symptoms were statistically worse on the gluten pill compared to the placebo, including abdominal pain, bloating, and depression.
Upon closer examination, however, the researchers noticed that 50 of the 59 subjects who completed the study (two dropped out) either had en equally negative response to gluten or placebo (likely due to the nocebo effect), showed no statistically significant differences, or experienced a worse response to the rice starch pill! In other words, the researchers identified only nine subjects who they suspected might actually be sensitive to gluten.
A result like this could easily occur due to random chance. It also could be explained by the study design. After one week on a gluten-free diet, even people without gluten sensitivity would likely experience adverse gastrointestinal symptoms when reintroduced to gluten. Sadly, however, the researchers did not have a control group of subjects without suspected NCGS, which they noted as a limitation.
Despite one report that the study offers a "physical explanation" for NCGS, the authors very clearly refute this.
"Our study does not provide any progress in identifying possible biomarkers of NCGS."
Far from proving that gluten sensitivity is real, at best, what the current study tells us is that only a small fraction of people who think they have NCGS may actually have the condition, if indeed it exists at all.
Source: Di Sabatino, Volta, Salvatore, Biancheri, Caio, De Giorgio, Di Stefano, Corazza GR. "Small Amounts of Gluten in Subjects with Suspected Nonceliac Gluten Sensitivity: a Randomized, Double-Blind, Placebo-Controlled, Cross-Over Trial." Clin Gastroenterol Hepatol. 2015 Feb 19. pii: S1542-3565(15)00153-6. doi: 10.1016/j.cgh.2015.01.029