Published in Gastroenterology, the study found that participants who do not suffer from celiac disease or gluten sensitivity experience no abdominal pain, constipation, diarrhea or reflux because of gluten consumption.
This is the first de-randomised clinical trial to demonstrate that consumption of gluten-containing flour does not generate symptoms in healthy volunteers.
The study team included researchers from the University of Reading, University of Sheffield and Sheffield Teaching Hospitals NHS Foundation Trust.
Dr. Paola Tosi, senior research fellow from the University of Reading, said: "It appears that gluten is often unjustifiably given the role of the bad guy in our diet, while gluten containing cereals, particularly when wholegrain, represent an important source of protein, fibre and micronutrients."
The researchers state in their report that the gluten-free diet could be 'overall sub-optimal', adding "there is possibly clinical justification in actively discouraging people from starting it if they have no diagnosable sensitivity."
Method
The team asked healthy volunteers to adopt a gluten-free diet (GFD) in the two weeks preceding the start of the trial in order to establish baseline scores for stomach complaints.
The volunteers were then randomised into two groups, receiving either organic gluten or a gluten-free blend in the form of flour sachets to add to their diet twice daily for two weeks while otherwise continuing their GFD.
Sachets contained either organic gluten (vital gluten sachets, daily, providing 14 g gluten protein and 1.4 g starch carbohydrates), or a gluten-free blend (rice, potato, tapioca, maize, and buckwheat flour blend).
Going gluten-free unnecessarily
Professor David Sanders, an honorary professor of gastroenterology at the University of Sheffield and a consultant gastroenterologist at Sheffield Teaching Hospitals NHS Foundation Trust, said: "The results of the paper show that 'going gluten-free' may not have any health benefits for many of those who avoid it in their diet on the belief that gluten is intrinsically 'bad' for the human gut.
"Gluten does not cause stomach problems in individuals who don't have a physiological susceptibility to it.
"Celiac disease driven by gluten affects 1% of the population and gluten sensitivity is a different condition which is increasingly recognised. Patients who have symptoms should not place themselves on a gluten-free diet but should seek advice from their doctor first."
Dr. Iain Croall, from the University of Sheffield's Department of Infection, Immunity and Cardiovascular Disease, said: "This study tries to draw a line between who benefits from a gluten-free diet and who doesn't. Medical research supports that gluten is fine for most to eat, but an idea has been developing that it is generally unhealthy for everyone.
"Following this, many people without any apparent issues now adopt the restrictive diet, while others seem to have pushed back at it entirely and believe that going gluten-free is a 'fad.
"This can cause real issues for people who do have clinical gluten sensitivity, as they are not always taken seriously in their medical needs."
The research paper notes that a gluten-free diet is the best treatment for a clinical gluten sensitivity such as celiac disease or non-celiac gluten sensitivity.
The team commented that the study lasted a relatively short time but also stressed that other academic literature suggests that any effects of gluten sensitivity would be seen after one week.
Source: Gastroenterology
Iain David Croall et al.
"Gluten Does Not Induce Gastrointestinal Symptoms in Healthy Volunteers: A Double-Blind Randomized Placebo Trial"
DOI: 10.1053/j.gastro.2019.05.015
Journal information: Gastroenterology