If you are a healthy person and follow a low-gluten, fiber-rich diet, you will probably experience less intestinal discomfort. In this article, the term ‘healthy person’ refers to people who say they are not allergic to gluten.
According to scientists at the University of Copenhagen, the reduction of intestinal discomfort is due to changes in gut bacteria. Specifically, changes in the composition and function of gut bacteria.
Healthy people on a low-gluten, fiber-rich diet also experienced a modest reduction in body weight.
The research team believes that the changes in the composition of dietary fibers had a bigger impact than the gluten itself on healthy adults.
Low gluten diet for non-allergic people
A growing number of people who are not allergic to gluten are opting for a low-gluten diet. This trend has triggered public debates about whether low-gluten diets are beneficial for people who are not allergic.
Researchers from Denmark, Belgium, Sweden, and New Zealand carried out a study looking into just that. They wrote about their study and findings in the journal Nature Communications (citation below).
In a press release, the University of Copenhagen wrote the following regarding the intervention study on healthy Danish adults:
“A low-gluten but fiber-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.”
Oluf Pedersen said:
“We demonstrate that, in comparison with a high-gluten diet, a low-gluten, fiber-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.”
Prof. Pedersen, the leading principal investigator of the trial, works at the Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen.
The authors carried out a randomized, controlled, cross-over trial involving sixty participants with two 8-week interventions. They were all middle-aged Danish adults.
The trial compared a low-gluten diet with a high-gluten diet. Low gluten included 2g of gluten per day, while high gluten included 18g of gluten per day. There was a washout period of 6+ weeks with a habitual diet of 12g of gluten per day.
The two diets had an identical number of calories and nutrients, as well as the same amount of dietary fibers. However, the composition of the fibers in the two diets was markedly different.
The University of Copenhagen wrote:
“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 fiber composition by reducing fibers from wheat and rye and replacing them with fibers from vegetables, brown rice, corn, oat and quinoa.”
High- and low-gluten diets
Under the high-gluten diet, dietary fibers from wheat and rye were rich in xylose and arabinose.
Under the low-gluten diet, dietary fibers in a variety of vegetables, berries, and non-wheat and non-rye cereals were rich in galactose and mannose.
Low-gluten diet – what advice to give
Prof. Pedersen said:
“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.”
“Also our study outcome is maybe a step forward in identifying novel prebiotics. That is, naturally occurring dietary fibres composed of mannose and galactose from non-wheat and non-rye cereals to boost a gut microbiota causing less bloating and a modest weight loss in healthy adults.”
“A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults,” Lea B. S. Hansen, Henrik M. Roager, Oluf Pedersen. Nature Communications volume 9, Article number: 4630 (2018). DOI: https://doi.org/10.1038/s41467-018-07019-x.