A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults

Abstract

Adherence to a low-gluten diet has become increasingly common in parts of the general population. However, the effects of reducing gluten-rich food items including wheat, barley and rye cereals in healthy adults are unclear. Here, we undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders with two 8-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). We find that, in comparison with a high-gluten diet, a low-gluten diet induces moderate changes in the intestinal microbiome, reduces fasting and postprandial hydrogen exhalation, and leads to improvements in self-reported bloating. These observations suggest that most of the effects of a low-gluten diet in non-coeliac adults may be driven by qualitative changes in dietary fibres.

Diet‐derived microbial metabolites in health and disease

“…We recently found that urine levels of enterolactone‐glucuronide increased following a low‐gluten diet (matched in total dietary fibre) compared with a high‐gluten diet (Hansen et al . ). Thus, microbial production of enterolactone may not only depend on the amount of dietary fibre but also on the type of dietary fibre.…”

“…Other examples of dietary manipulations resulting in observable microbiome changes include adoption of a low‐gluten diet (containing no dietary fibres from wheat, rye and barley; Hansen et al . ) or a low‐FODMAP diet (restricted in fermentable oligo‐, di‐, monosaccharides and polyols; Halmos et al . ; Staudacher et al .…”

“…However, diet-induced changes in gut microbiota composition following a short-term dietary intervention disappear as soon as the dietary manipulation is ceased (David et al 2014). Other examples of dietary manipulations resulting in observable microbiome changes include adoption of a low-gluten diet (containing no dietary fibres from wheat, rye and barley; Hansen et al 2018) or a low-FODMAP diet (restricted in fermentable oligo-, di-, monosaccharides and polyols; Halmos et al 2015;Staudacher et al 2017); both diets are characterised by elimination of specific fermentable dietary fibres. More moderate dietary changes, such as a shift to a wholegrain diet from a refined-grain diet, often result in limited effects on the gut microbiota composition (Lappi et al 2013;Vitaglione et al 2014;Korem et al 2017;Roager et al 2019).…”

“…Furthermore, enterolactone has been associated with intake of dietary fibre, wholegrains and vegetables (Johnsen et al 2004;Milder et al 2007). We recently found that urine levels of enterolactone-glucuronide increased following a lowgluten diet (matched in total dietary fibre) compared with a high-gluten diet (Hansen et al 2018). Thus, microbial production of enterolactone may not only depend on the amount of dietary fibre but also on the type of dietary fibre.…”

Fecal microbiota as a noninvasive biomarker to predict the tissue iron accumulation in intestine epithelial cells and liver

“…Linear discriminant analysis Effect size (LEfSe) was performed to identify differences in the microbial structure between groups, with the default parameter. 25 PICRUSt was used to identify differences in the metabolic pathways between each group against the KEGG. 26 Redundancy analysis (RDA) was performed by using "vegan" and "ggplot2" package of R. 22,23 The length of arrow represents the constraint effect of different environmental variables exerted on sample distribution in two-dimension.…”