the united states and is covered by worldwide copyright, can be represented in any colour. research research has attempted to discern, by double-blind placebo-controlled trials, between a "fad component" to the recent popularity of the gluten-free diet and an actual sensitivity to gluten or other components of wheat. in a 2013 double-blind, placebo-controlled challenge (dbpc) by biesiekierski et al. in a few people with irritable bowel syndrome, the authors found no difference between gluten or placebo groups and the concept of ncgs as a syndrome was questioned. nevertheless, this study had design errors and an incorrect selection of participants, and probably the reintroduction of both gluten and whey protein had a nocebo effect similar in all people, and this could have masked the true effect of gluten/wheat reintroduction. in a 2015 double-blind placebo cross-over trial, small amounts of purified wheat gluten triggered gastrointestinal symptoms (such as abdominal bloating and pain) and extra-intestinal manifestations (such as foggy mind, depression and aphthous stomatitis) in self-reported ncgs. nevertheless, it remains elusive whether these findings specifically implicate gluten or proteins present in gluten-containing cereals. a 2016 review of the recent research advancements in understanding diet's role in attenuating ibs patient's symptoms concluded that gluten was a common trigger. however, because on the different compounds responsible for symptoms, many patients that could be inaccurately labelled non-coeliac gluten sensitive; and it may be more appropriate to use nomenclature such as "non-coeliac wheat sensitive" (ncws), "non-coeliac wheat protein sensitive" (ncwps), or even fodmap sensitive when referring to these patients. in a 2018 double-blind, crossover research study on 59 persons on a gluten-free diet with challenges of gluten, fructans or placebo, intestinal symptoms (specifically bloating) were borderline significantly higher after challenge with fructans, in comparison with gluten proteins (p=0.049). although the differences between the three interventions was very small, the authors concluded that fructans (the specific type of fodmap found in wheat) are more likely to be the cause of ncgs gastrointestinal symptoms, rather than gluten. in addition, fructans used in the study were extracted from chicory root, so it remains to be seen whether the wheat fructans produce the same effect.