An increasing number of people choose a low-gluten diet, even though they are not allergic to the dietary substance. This trend has sparked public debate about whether or not low-gluten diets are recommendable for people without allergies. Now, researchers from University of Copenhagen among others have looked into just that.
In an intervention study of healthy Danish adults, reported today in Nature Communications,
an international team of scientists shows that a low-gluten but
fibre-rich diet changes the community of gut bacteria and decreases
gastrointestinal discomfort such as bloating and is linked to a modest
weight loss. The changes in intestinal comfort and body weight relate to
changes in gut bacteria composition and function.
"We demonstrate that, in comparison with a high-gluten diet, a
low-gluten, fibre-rich diet induces changes in the structure and
function of the complex intestinal ecosystem of bacteria, reduces
hydrogen exhalation, and leads to improvements in self-reported
bloating. Moreover, we observed a modest weight loss, likely due to
increased body combustion triggered by the altered gut bacterial
functions," explains the leading principal investigator of the trial,
Professor Oluf Pedersen, Novo Nordisk Foundation Center for Basic
Metabolic Research at University of Copenhagen.
Change in dietary fibre composition seems to be the cause
The researchers undertook a randomised, controlled, cross-over
trial involving 60 middle-aged healthy Danish adults with two eight week
interventions comparing a low-gluten diet (2 g gluten per day) and a
high-gluten diet (18 g gluten per day), separated by a washout period of
at least six weeks with habitual diet (12 g gluten per day).
The two diets were balanced in number of calories and nutrients
including the same amount of dietary fibres. However, the composition of
fibres differed markedly between the two diets.
Based on their observations of altered food fermentation patterns of
the gut bacteria, the researchers conclude that the effects of
low-gluten dieting in healthy people may not be primarily due to reduced
intake of gluten itself but rather to a change in dietary fibre
composition by reducing fibres from wheat and rye and replacing them
with fibres from vegetables, brown rice, corn, oat and quinoa.
No basis for change of diet recommendation yet
A low-gluten diet has previously been proposed to diminish
gastrointestinal symptoms in patients with inflammatory bowel diseases
and irritable bowel syndrome, disorders which occur in up to 20 percent
of the general Western population.
The present study suggests that even some healthy individuals may
prefer a low-gluten diet to combat intestinal discomfort or excess body
"More long-term studies are definitely needed before any public
health advice can be given to the general population. Especially,
because we find dietary fibres - not the absence of gluten alone - to be
the primary cause of the changes in intestinal discomfort and body
weight. By now we think that our study is a wake-up call to the food
industry. Gluten-free may not necessarily be the healthy choice many
people think it is. Most gluten-free food items available on the market
today are massively deprived of dietary fibers and natural nutritional
ingredients. Therefore, there is an obvious need for availability of
fibre-enriched, nutritionally high-quality gluten-free food items which
are fresh or minimally processed to consumers who prefer a low-gluten
diet. Such initiatives may turn out to be key for alleviating
gastro-intestinal discomfort and in addition to help facilitating weight
control in the general population via modification of the gut
microbiota", concludes senior lead investigator, Professor Oluf