Another reason that contributed to this trend was the publication of several books that demonize gluten and point to it as a cause of type 2 diabetes, weight gain and obesity, and a broad list of conditions ranging from depression and anxiety to arthritis and autism. The book that has had the most impact is Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar – Your Brains Silent Killers, by the American neurologist David Perlmutter, published in September 2013. Another book that has had great impact is Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back to Health, by cardiologist William Davis. The gluten-free diet has been advocated and followed by many celebrities to lose weight, such as Miley Cyrus and Gwyneth Paltrow, and some elite athletes to improve performance.Estimates suggest that in 2014, 30% of people in the US and Australia were consuming gluten-free foods, with estimates that by 2016 approximately 100 million Americans would consume gluten-free products. Data from a 2015 Nielsen survey of 30,000 adults in 60 countries around the world showed that 21% of people prefer to buy gluten-free foods, with interest highest among younger generations. Another school of thought suggests that many people may be unnecessarily avoiding gluten when they do not need to.Debate around NCGS as a genuine clinical condition can be heightened because often patients are self diagnosed, or a diagnosis is made by alternative health practitioners.
in a few people with IBS, 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. 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. See also
Gluten-related disorders


== References ==