What is it all about?
Laura Pirkola, Swedish University of Agricultural Sciences, Faculty of Natural Resources and Agricultural Sciences, Department of Molecular Sciences, presents results from her thesis that rye may have the potential to increase the production of the short-chain fatty acid butyrate (butyric acid). Rye has been shown to increase butyrate levels in previous human studies, but the effects on the gut-brain axis are still unclear.
What was the thesis about and why is it interesting?
The thesis consisted of two studies, one of which compared different compositions of microbiota through lab fermentation of whole grain rye bread, whole grain oat bread and refined bread. The second study was a dietary intervention in which healthy participants ate large amounts of either wholemeal rye bread or low-fiber bread for three weeks. The aim of this thesis was to investigate how dietary fiber from different breads affects gut bacteria and the substances they produce, and to see if wholemeal rye bread could affect the gut-brain connection. Interest in how gut bacteria and the gut-brain axis affect our health has increased a lot recently, but there is still a lot we don't know about the health benefits of whole grains. It is believed that whole grains can affect the brain, either directly or by affecting gut bacteria and their communication with the brain.
What do the results show?
Differences were observed in short-chain fatty acids and other metabolite levels and how dietary fiber was consumed between the samples with microbiota from different donors. This indicates that the composition of the microbiota may influence how nutrients from bread are used by the bacteria. Levels of a specific short-chain fatty acid, butyrate, differed between the two donors, especially in the rye samples. Butyrate is considered a key metabolite in the gut-brain axis. No significant changes in fecal microbiota composition or gut-brain axis were observed in the three-week study with subjects. A slight increase in the amount of two microbes that produce butyrate was observed in the participants who consumed whole grain rye.
What is needed going forward?
It can be assumed that certain cereals or dietary fibers benefit individuals with a specific microbiota composition. The growing body of evidence on the role of gut microbiota composition and its effect on microbiota-derived metabolites presents an interesting approach to precision nutrition and product innovation. However, knowledge of the complex interactions between microbiota composition, dietary fiber utilization and health effects is still very limited, and microbiota composition analysis is not accessible to all. Therefore, it is beneficial to recommend increased intake of whole grains and the amount and variety of dietary fiber in the diet. Link to publication :
Gut-brain axis: the gut-brain axis is a two-way communication pathway between the gut and the brain in which the gut microbiota plays a central role. There is a large individual variation in the composition of the gut microbiota, which can affect its ability to produce different metabolites.
Short-chain fatty acids: When dietary fibers are fermented in the intestines, short-chain fatty acids are formed, which are important for our health as they nourish the intestines and can affect human immunity.