Microbiology: Modest effects of a low-gluten diet on gut microbiota

A low-gluten diet induces moderate changes in the gut microbiota and physiology of 60 healthy people, reports an article published in Nature Communications. The authors suggest that most of these effects may be driven by qualitative changes in dietary fibres upon reduction of gluten-rich food items.

Gluten is a major component in wheat, rye and barley, and consists of proteins that are partially resistant to digestion. It can be harmful to people suffering from certain disorders such as coeliac disease. However, the effects of reducing gluten intake on healthy people have remained unclear.

Oluf Pedersen and colleagues undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders. The trial consisted of 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 period of at least six weeks with habitual diet (12 g gluten per day). The authors found that, in comparison with the high-gluten diet, the low-gluten diet induced moderate changes in the intestinal microbiome (including reduced abundance of Bifidobacterium species) and certain urine metabolites, and led to improvements in self-reported bloating.

The two diets differed not only in gluten content but also in the composition of dietary fibres. Therefore, the observed effects might result from the changes in dietary fibres upon reduction of gluten-rich food items, rather than by the reduction of gluten intake itself. Furthermore, how these results might generalize to other populations of different age, ethnic background or lifestyles is yet to be determined, the authors conclude.