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Gluten-free diets won’t help healthy guts

Healthy people who avoid gluten by choice may not get any benefit from the gluten-free restriction on their diet, according to new research.

The study, published in Gastroenterology, found that participants who took part in a randomised control trial did not report any stomach problems associated with gluten consumption, compared to a gluten-free control group.

A team from the University of Sheffield, Sheffield Teaching Hospitals NHS Foundation Trust and the University of Reading asked healthy volunteers who didn’t have a clinical diagnoses of coeliac disease or gluten sensitivity to take part in the trial.

The participants were asked 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 such as abdominal pain, constipation, diarrhoea and reflux.

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. The test group who took gluten didn’t report any ill effects compared to the control group.

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.

“Coeliac disease driven by gluten affects one per cent 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.”

Dr Paola Tosi, Senior Research Fellow from the University of Reading, added: “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 research paper notes that a gluten-free diet is the best treatment for a clinical gluten sensitivity such as coeliac disease or non-coeliac 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.

Croall, I.D., Aziz, I.,Trott, N.,Tosi, P., Hoggard, N., and Sanders, D.S., 2019, Gluten Does Not Induce Gastrointestinal Symptoms in Healthy Volunteers: A Double-Blind Randomized Placebo Trial. Gastroenterology 2019; DOI: 10.1053/j.gastro.2019.05.015